T HR EL 19002 ST Protection System Requirements for the ...

© State of NSW through Transport for NSW 2020

Protection System Requirements for the High Voltage Network

T HR EL 19002 ST

Standard

Version 1.0

Issue date: 26 November 2020

T HR EL 19002 ST Protection System Requirements for the High Voltage Network

Version 1.0 Issue date: 26 November 2020

© State of NSW through Transport for NSW 2020

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© State of NSW through Transport for NSW 2020 of 80

Standard governance

Owner: Lead Electrical Engineer, Asset Standards Authority

Authoriser: Chief Engineer, Asset Standards Authority

Approver: Executive Director, Asset Standards Authority on behalf of the ASA Configuration Control Board

Document history

Version Summary of changes

1.0 First issue.




Preface The Asset Standards Authority (ASA) is a key strategic branch of Transport for NSW (TfNSW).

As the network design and standards authority for NSW Transport Assets, as specified in the

ASA Charter, the ASA identifies, selects, develops, publishes, maintains and controls a suite of

requirements documents on behalf of TfNSW, the asset owner.

The ASA deploys TfNSW requirements for asset and safety assurance by creating and

managing TfNSW's governance models, documents and processes. To achieve this, the ASA

focuses on four primary tasks:

• publishing and managing TfNSW's process and requirements documents including TfNSW

plans, standards, manuals and guides

• deploying TfNSW's Authorised Engineering Organisation (AEO) framework

• continuously improving TfNSW’s Asset Management Framework

• collaborating with the Transport cluster and industry through open engagement

The AEO framework authorises engineering organisations to supply and provide asset related

products and services to TfNSW. It works to assure the safety, quality and fitness for purpose of

those products and services over the asset's whole-of-life. AEOs are expected to demonstrate

how they have applied the requirements of ASA documents, including TfNSW plans, standards

and guides, when delivering assets and related services for TfNSW.

Compliance with ASA requirements by itself is not sufficient to ensure satisfactory outcomes for

NSW Transport Assets. The ASA expects that professional judgement be used by competent

personnel when using ASA requirements to produce those outcomes.

About this document

This standard has been updated from RailCorp document EP 19 00 00 02 SP Protection

System Requirements for the High Voltage network, version 4.1.

EP 19 00 00 02 SP is withdrawn with the publication of this standard.

The major changes from the RailCorp version of the document include the following:

• addition of type approval requirements

• addition of protection design documentation requirements

• clarification of allocation of dc auxiliary supply for two battery locations

• installation of frame leakage on all rectifier transformers

• incorporation of TN 039:2015 for requirements of line differential schematic drawings

• incorporation of TN 028:2018 for protection requirements of harmonic filters




• update of the standard test block wiring protection relay input/output configurations

• addition of requirements for copper pilot wire schemes

• change in terminology from pilot wire to line differential

This standard is a first issue.




Table of contents 1. Introduction .............................................................................................................................................. 8

2. Purpose .................................................................................................................................................... 8 2.1. Scope ..................................................................................................................................................... 8 2.2. Application ............................................................................................................................................. 9

3. Reference documents ............................................................................................................................. 9

4. Terms and definitions ........................................................................................................................... 10

5. Type approval ........................................................................................................................................ 11

6. General protection philosophy ............................................................................................................ 12 6.1. Protection current trip settings ............................................................................................................. 12 6.2. Protection time grading settings .......................................................................................................... 12

7. Protection design documentation ....................................................................................................... 13 7.1. Content of HV protection concepts ...................................................................................................... 13 7.2. Schematic and scheme drawings ........................................................................................................ 14

8. Specific protection equipment requirements ..................................................................................... 15 8.1. Protection equipment design principles for HV switchgear ................................................................. 15 8.2. Strategic substations ........................................................................................................................... 16 8.3. Fibre optic ............................................................................................................................................ 17 8.4. Interfacing new protection schemes with existing equipment ............................................................. 17 8.5. Current transformers ............................................................................................................................ 18 8.6. Voltage transformers ........................................................................................................................... 21 8.7. Auxiliary supply (dc) ............................................................................................................................. 23 8.8. Protection relays and test blocks ......................................................................................................... 24 8.9. ACCB close inhibit ............................................................................................................................... 24 8.10. Protection alarms ............................................................................................................................. 25 8.11. Intertrip arrangements ..................................................................................................................... 25

9. Specific equipment applications.......................................................................................................... 25 9.1. 132 kV feeders ..................................................................................................................................... 25 9.2. 33 kV and 66 kV feeders ..................................................................................................................... 25 9.3. 11 kV feeders ....................................................................................................................................... 27 9.4. High voltage busbars and bus-tie cables ............................................................................................. 29 9.5. Rectifier transformer and rectifier power cubicle ................................................................................. 31 9.6. System transformers ............................................................................................................................ 32 9.7. 11 kV / 415 V transformers supplied from ring main units ................................................................... 34 9.8. 11 kV / 415 V transformers supplied from SCADA controlled ACCBs ................................................ 34 9.9. Harmonic filters .................................................................................................................................... 35 9.10. Protection SCADA alarms ............................................................................................................... 38

10. Voltage and current transducers ......................................................................................................... 38

Appendix A ACCB trip coils................................................................................................................... 39

Appendix B Two battery systems (125 V dc) – allocation of battery to protection equipment ...... 41




Appendix C Protection relay identification .......................................................................................... 42

Appendix D Standard test block wiring and input/output relay configuration ................................. 43 D.1. Line differential protection .................................................................................................................... 44 D.2. Feeder over-current and earth fault protection .................................................................................... 47 D.3. Rectifier protection ............................................................................................................................... 50 D.4. System transformer protection............................................................................................................. 54 D.5. Buszone and bus-tie protection ........................................................................................................... 60 D.6. Harmonic filter protection ..................................................................................................................... 62

Appendix E Auto re-close on high voltage feeders ............................................................................ 65

Appendix F Implementation of SCADA alarms and control ................................................................... 66

Appendix G Typical ACCB auxiliary supply arrangement .................................................................. 67

Appendix H Protection labelling guidelines......................................................................................... 69 H.1. Location of labels ................................................................................................................................. 69 H.2. Colour of labels .................................................................................................................................... 69 H.3. Format .................................................................................................................................................. 69 H.4. Content ................................................................................................................................................ 70 H.5. Examples of labels ............................................................................................................................... 70

Appendix I Standard current transformer configurations .................................................................... 73

Appendix J Metering requirements for bulk supply points ................................................................... 75 J.1. Voltage transformers ........................................................................................................................... 75 J.2. Current transformers ............................................................................................................................ 75 J.3. Current transformer and voltage transformer test results .................................................................... 76 J.4. Secondary wiring from HV switchboard to meter panel ...................................................................... 76 J.5. 240 V ac supply to metering panel ...................................................................................................... 76 J.6. Metering panel ..................................................................................................................................... 76

Appendix K Wire identification for current transformer, voltage transformer, general protection 77

Appendix L Harmonic filter connection diagram .................................................................................... 79

Appendix M Requirements for copper pilot wire schemes ................................................................. 80




1. Introduction The RailCorp high voltage (HV) alternating current (ac) networks are nominal voltages of 11 kV,

33 kV, 66 kV and 132 kV and include equipment such as HV switchboards, HV feeders, air

break switches, system transformers, rectifier transformers, and harmonic filters.

Further background information on the RailCorp HV network and general information on

RailCorp electrical infrastructure and assets is detailed in T HR EL 00001 TI RailCorp Electrical

System General Description.

2. Purpose The purpose of this document is to specify the protection requirements for the RailCorp HV

distribution network.

The prescriptive nature of this standard is to ensure:

• HV protection schemes and associated infrastructure are designed and implemented to

provide a safe and operationally reliable HV distribution network and traction supply.

• Consistency with the design of protection schemes and their implementation to enable

efficient fault finding and maintenance by operation and maintenance staff.

• Design documentation is comprehensive and accurate to enable fault finding and allow for

future modification.

Innovative approaches to HV protection that provide demonstrable value to TfNSW and our

stakeholders are encouraged, but require careful consideration in this area. Early consultation

with the Lead Electrical Engineer, ASA is essential to facilitate a concession in accordance with

T MU MD 00011 ST Concessions to ASA Requirements.

Refer to T HR EL 19001 ST Protection System Requirements for the 1500 V DC Network for

details of protection requirements for the 1500 V dc network.

2.1. Scope This document covers the protection system requirements for the RailCorp HV distribution

network for 11 kV, 33 kV, 66 kV and 132 kV system voltages.

This document covers the general design principles for protection schemes, general setting

requirements and specific requirements for protection schemes associated with the following

equipment:

• HV feeders

• HV busbars, HV bus-ties




• system transformers, rectifier transformers, distribution transformers and 11 kV auxiliary

transformers

• HV harmonic filters

This document does not include requirements for equipment used for detection and

measurement of non-electrical protection parameters (such as oil and gas sudden pressure

change, temperature measurement), other than to specify necessary interface details.

2.2. Application This document applies to all new installations and existing installations that are modified and

refurbished.

HV protection systems existing at the date of release of this document are not affected by the

requirements of this document.

3. Reference documents The following documents are cited in the text. For dated references, only the cited edition

applies. For undated references, the latest edition of the referenced document applies.

International standards

IEEE C37.2: 2008 Electrical Power System Device Function Numbers, Acronyms, and Contact

Designations

Australian standards

AS 1675 Current Transformers – Measurement and Protection

AS 2067 Substations and high voltage installations exceeding 1 kV a.c.

AS/NZS 2373 Electric cables - Twisted pair for control and protection circuits

AS 60044.1 Instrument transformers – Part 1: Current transformers

AS 60044.2 Instrument transformers – Part 2: Inductive voltage transformers

Transport for NSW standards

EP 00 00 00 15 SP Common Requirements for Electrical Power Equipment

EP 06 00 00 01 SP System Substation Battery & Battery Charger

T HR EL 00001 TI RailCorp Electrical System General Description

T HR EL 03001 ST Controls and Protection for 1500 V dc Rectification Equipment

T HR EL 11001 PR Design Technical Reviews for Electrical SCADA Equipment

T HR EL 11001 TI SCADA Standard I/O Schedule




T HR EL 11004 ST Electrical SCADA Interface Requirements

T HR EL 19001 ST Protection System Requirements for the 1500 V DC Network

T HR TE 01001 ST Communication Outdoor Cabling

T HR TE 21003 ST Telecommunications for Traction Substations and Section Huts

T MU MD 00005 GU Type Approval of Products

T MU MD 00011 ST Concessions to ASA Requirements

Transport for NSW drawings

EL0283030 Substations – 33kV Transformer Frame Leakage - Arrangement

EL0661206 Lewisham-Strathfield, Substations, 11kV Feeder 533, Line Differential Protection,

Schematic Diagram

EL0692659 Blaxland-Faulconbridge, Substations, 66kV Feeder 864, Line Differential Protection,

Schematic Diagram

Sydney Trains documents

SP D 79036 - Sydney Trains Electricity Distribution Network Bushfire Risk Management Plan

Other reference documents

Ausgrid Network Standard, ES3 Metering Installation Requirements Part A, Document NW000-

S0141, July 2018

Australian Energy Market Commission, National Electricity Rules

Endeavour Energy Metering Design Instruction, High Voltage Measurement Current and

Voltage Transformers, Document No: MET 0002 (amendment 0)

NSW Department of Planning, Industry and Environment, Service and Installation Rules of New

South Wales

TransGrid, Secondary Systems Design Standard

4. Terms and definitions The following terms and definitions apply in this document:

ACCB alternating current circuit breaker

CT current transformer

DC direct current

DCCB direct current circuit breaker

HV high voltage

IT intertrip




LV low voltage

MTA protection relay used for the multi-tripping of ACCBs; this is an automatically reset relay

with a hand reset flag

MTM protection relay used for the multi-tripping of ACCBs; this is a manually reset relay with a

hand reset flag

RMU ring main unit

RTU remote terminal unit (interface to SCADA system)

SCADA supervisory control and data acquisition system

SEF sensitive earth fault

SRR send receive relay

substation the following are locations within the RailCorp HV distribution network which are

classified as substations for the purpose of this document:

• any location that includes a high voltage ACCB

• traction substation

• high voltage switching station

• high voltage switchroom

system transformers are defined as having the following voltage ratio 132/66 kV, 132/33 kV,

66/33 kV, 66/11 kV, 33/11 kV

TBK test block

TCS trip circuit supervision

5. Type approval All high voltage (HV) protection relays (for example, electro-mechanical, numerical, multi-trip)

and relay test blocks require type approval by the ASA prior to being connected to the RailCorp

electrical network.

The type approval of HV switchgear includes the associated protection and control schematic

drawings which detail implementation of protection schemes in accordance with this standard.

Type approval processes and requirements are contained in T MU MD 00005 GU Type

Approval of Products.




6. General protection philosophy In designing the protection schemes for RailCorp’s HV distribution network, the following

principles shall be applied:

• All HV faults shall be detected and able to be cleared by two independent sets of protection

(primary and backup). HV alternating current circuit breakers (ACCBs) or fuses can be

used to clear the fault.

• The primary and backup protection schemes shall be independent (separate current

transformers (CTs), protection relays, ACCB trip coil and direct current (dc) auxiliary

supply).

• The rated continuous thermal current of the CTs shall not constrain the rating of associated

power system elements.

• Primary protection for feeders, HV busbars, HV bus-ties and system transformers shall be

implemented using unit schemes except as detailed in Section 9.3 and Section 9.4.

• The protection schemes shall be designed to eliminate or manage ‘blind spots’.

Section 6.1 and Section 6.2 provide requirements for determining protection settings.

6.1. Protection current trip settings The following principles should be applied when determining the protection current trip settings:

• The protection should be set to operate at not more than 2/3 of the minimum phase to

phase fault and not more than 2/3 of the minimum earth fault.

• The over-current protection settings should be, as far as practicable, at least 1.5 times the

maximum load current.

• Relay settings should be, as far as practicable, at least 1.5 times the highest downstream

setting.

6.2. Protection time grading settings The following principles shall be applied when determining the protection time grading:

• Fault clearing times shall be minimised.

• The protection shall be graded to ensure that the fault is cleared by the protection closest

to the fault, and that the area of interruption is minimised.




In addition, the following should be provided:

• To ensure discrimination, a 0.3 s grading margin should be provided for protection in

successive zones.

• The breaker fail time setting should be 0.2 s.

7. Protection design documentation The design documentation for HV protection schemes (excluding protection settings) and the

associated equipment consist of the following:

• A HV protection concept, which details the protection requirements. The protection concept

shall be a version controlled document that is produced by the operator and maintainer.

See Section 7.1 for details on the content of a protection concept.

• HV equipment drawings such as single line diagrams and ACCB control and protection

schematics. These are developed from the protection concept by the equipment

manufacturers and design AEO.

• Line differential scheme schematic (where required) that is produced by the design AEO.

Section 7.1 and Section 7.2 provide detail on the protection concept and schematic drawing

requirements.

7.1. Content of HV protection concepts The protection concept consists of a written document (compatible with Microsoft Word) and a

single line diagram that is developed from the approved proposed HV operating diagrams.

The protection concept diagram should contain the following:

• substation HV busbars, ACCBs, air break switches and links, voltage transformers (VTs),

transformers, location of CTs and details of the interfacing substations

• connection between protection relays and associated CTs and VTs, and connection to the

ACCB trip coils

• electrical ratings of CTs, VTs, and ratings of the HV switchgear, the HV busbar and ACCBs

• protection relay type and model

• interconnection to adjacent substations and relevant details of the HV protection scheme at

the remote substation

The HV busbar and the order of associated equipment shall match the approved operating

diagram for the location.




Existing protection equipment and interconnection is shown in blue, new equipment and

interconnection in red, and equipment to be removed in green. The busbar, ACCBs, and VTs

are shown in black.

The Word-compatible document should contain the following:

• specific protection and alarm details for each protection scheme at the location

• the protection relay type and model, specific ACCB tripped and associated trip coil, CT

ratio and class, location of CT, details on circuit breaker fail operation and corresponding

ACCBs tripped, trip circuit supervision (TCS) details

• intertrip details and communication circuit for line differential scheme

• list of alarms and indications and detail on whether hardwired or on a serial link

• specific metering requirements, details on analogues

• VT requirements, including location, size and class, associated alarms and analogues,

transducer manufacturer and model

• ACCB control, indication and protection relay supply voltage details

• protection relay models with complete part number

• scope of modifications required at interface substations if required

• relay and test block configuration when not documented or when differing from that

documented in this standard

• battery allocation when there are two battery systems in the substation

• detailed testing and commissioning requirements for protection equipment

7.2. Schematic and scheme drawings The majority of HV feeders on the RailCorp HV distribution network have a line differential

protection scheme installed.

Where a line differential scheme is installed, in addition to the schematic diagrams produced for

the individual equipment at either end of the scheme, an overall ‘line differential’ schematic

drawing is required to be produced.

The following drawings provide examples of the typical content and layout to be included on the

diagram:

• EL0661206 Lewisham-Strathfield, Substations, 11kV Feeder 533, Line Differential

Protection, Schematic Diagram

• EL0692659 Blaxland-Faulconbridge, Substations, 66kV Feeder 864, Line Differential

Protection, Schematic Diagram




When an existing line differential scheme is being modified then the associated schematics and

the line differential schematic drawing shall be modified.

If an existing line differential scheme is being modified and a line differential schematic drawing

does not exist, then the design AEO is responsible for producing a line differential schematic

drawing.

Where an additional substation is installed between two existing substations that results in the

existing line differential scheme becoming two schemes, there shall be a line differential

schematic for each individual scheme. The design AEO is responsible for producing the

schematics.

7.2.1. Content and layout of line differential scheme drawing The content of the line differential schematic diagram should typically include the following for

both ends of the scheme:

• HV busbars, associated ACCBs, air break switches (ABS) and links

• CTs (including CTs used for other protection schemes) with secondary circuitry connection

to the line differential relay; CTs to be shown in correct position and polarity identified

• VTs

• line differential relays and associated test blocks, with all connections to the relay detailed

and referenced to the equipment schematic drawings

• auxiliary supply to the line differential relay and supervisory control and data acquisition

system (SCADA) alarms

• schematic representation of the communication scheme between line differential relays

• relevant notes and an item list

8. Specific protection equipment requirements Section 8.1 through to Section 8.11 provide requirements for specific protection equipment.

8.1. Protection equipment design principles for HV switchgear To ensure the independence and integrity of protection schemes, the following principles shall

apply:

• Protection current transformers shall be connected to protection equipment only.

• Individual protection schemes shall be connected to dedicated current transformers.




• Primary and backup protection schemes shall be implemented using separate protection

relays.

• Where the primary and backup scheme trip the same HV ACCB, the following shall apply:

o The primary and backup schemes shall use separate trip coils, one trip coil for the

primary scheme, the second trip coil for the backup scheme. See Appendix A for

standard trip coil allocations and Appendix G for typical HV switchboard

arrangements.

o Each scheme shall have its own individual dc auxiliary supply from a dedicated circuit

originating at the distribution board.

• Where the substation has two dc auxiliary supplies (see Section 8.7.2) the battery

allocation for primary and backup protection schemes shall vary across the batteries for

feeders, rectifiers and buszone protection.

• SCADA monitored TCS with local indication shall be provided for all HV ACCB trip circuits.

The TCS scheme shall monitor the trip circuit with the ACCB in the open and closed

position. It should be implemented as a function of the protection relay. If the existing

protection relays do not have TCS functionality then a dedicated TCS relay shall be used.

• The auxiliary supply for each buszone and bus-tie protection scheme shall be from a

dedicated circuit originating at the distribution board. Where the protection relay is an

electromechanical type then the auxiliary supply shall be monitored with an alarm from the

monitoring relay connected to the SCADA system.

8.2. Strategic substations At strategic substations additional protection and auxiliary supplies are required to ensure the

reliability and operability of the HV distribution networks and subsequently the supply to critical

infrastructure and the 1500 V dc traction supply.

The criteria determining whether a substation is classed as a strategic substation are as follows:

• connectivity of the substation (four or more HV feeders) within the RailCorp HV distribution

network

• maximum HV fault level and the margin to the rated short-time withstand current capacity

of the switchgear installed at the substation

• criticality of the substation within the rail system

Examples of critical substations are main supply substation for city circle or rail tunnel,

substation at a rail junction, last traction substation on a radial rail line.

• complexity of the protection schemes and any resulting compromises in the protection

coordination




The protection requirements for 11 kV feeders are determined from the criticality of the 11 kV

feeder. The following is the criteria for determining whether an 11 kV feeder is classed as

critical:

• 11 kV feeders supplying underground railway stations

• 11 kV feeders installed in tunnels

• 11 kV feeders supplying installations deemed to be operationally critical (for example,

major signal boxes, operating centres)

• 11 kV feeders where it is time critical to clear the fault due to high fault levels or bushfire

hazards

8.3. Fibre optic The majority of line differential schemes installed in the RailCorp network communicate over

fibre optic and intertripping is also implemented by means of the fibre optic network.

The security of the fibre optic network is critical in ensuring the reliability of the HV protection

schemes and all fibre optic cabling shall comply with T HR TE 21003 ST Telecommunications

for Traction Substations and Section Huts and T HR TE 01001 ST Communication Outdoor

Cabling.

8.4. Interfacing new protection schemes with existing equipment Section 8.4.1 through to Section 8.4.4 provide requirements for interfacing new protection

schemes with existing equipment.

8.4.1. Multiple use of current transformers More than one protection scheme (maximum two schemes) can be connected to the same set

of CTs provided the following are satisfied:

• Installation of additional CTs is not economically feasible (for example, ACCB would have

to be replaced; additional post type CTs would be required).

• The protection schemes are not the primary and backup protection for the same

equipment.

• A failure of the CTs will not result in a piece of equipment having no protection due to an

existing compromise in the protection system.

• The output of the current transformers shall be sufficient for the burden of all the connected

protection schemes and associated equipment to ensure that each scheme operates as

required up to the available fault level.




8.4.2. Trip circuit supervision Where a new protection scheme is interfacing with existing switchgear that does not have TCS

installed, then TCS shall be implemented either as a function of the protection relay or a

dedicated TCS relay installed.

8.4.3. Breaker fail When new protection relays that have breaker fail functionality are installed in an existing

substation, the breaker fail detection shall result in the energising of a multi-trip relay. The multi-

trip relay shall trip the following:

• all the associated ACCBs on the busbar

• remote end ACCB for all feeders on the busbar

• both HV ACCBs associated with a system transformer with the breaker fail fault

The multi-trip relay can be the same relay used for buszone protection.

8.4.4. Intertrip implemented with copper pilots If a breaker fail function is associated with a feeder that has a line differential scheme utilising

copper pilots, then an intertrip can be implemented by destabilising the line differential scheme.

When destabilising the line differential scheme this shall be implemented at the line differential

relay.

8.5. Current transformers All protection and metering CTs shall comply with AS 60044.1 Instrument transformers – Part 1:

Current transformers, unless they are required to interface with existing protection schemes that

have CTs specified in accordance with AS 1675 Current Transformers – Measurement and

Protection.

• CTs shall be rigidly clamped to prevent movement under short circuit conditions.

• CTs shall safely withstand the mechanical and thermal stresses due to a short circuit equal

to the full short circuit rating of the switchgear.

• CTs shall have a minimum rated continuous thermal current of at least 150% of rated

primary current unless modified by the protection concept for the specific location.

The CTs shall be installed with polarity markings assuming supply from the busbar in all cases.

See Appendix I for requirements of CT polarity.

CTs that are not connected to a protection or metering relay shall have their secondary winding

shorted in the low voltage compartment and earthed.

Section 8.5.1 through to Section 8.5.5 provide requirements for current transformers.




8.5.1. CT rating plates and terminal markings CTs shall be provided with rating plates and terminal markings as specified in AS 60044.1. The

rating plates shall be mounted in such a manner that they are visible.

HV switchboards shall have a set of rating plates in the compartment housing the CTs and also

in the corresponding low voltage (LV) compartment.

The CT terminals shall be clearly marked to enable correct selection of the ratio. The associated

rating plate shall also be marked with the information to enable correct selection of the ratio.

The CT terminals should be readily accessible.

8.5.2. Location and order of CTs See Section 9.2.5 for CT location requirements for 33 and 66 kV feeders.

See Section 9.3.6 for CT location requirements for 11 kV feeders.

See Section 9.4.4 for CT location requirements for HV busbars and bus-ties.

See Section 9.6.6 for CT location requirements for system transformers.

See Section 9.9.11 for CT location requirements for harmonic filters.

8.5.3. Current transformers for protection Protection CTs shall be of a class entirely suitable for the connected equipment so as to give

correct operation under all service and fault conditions.

The following is the standard accuracy class:

• differential schemes – PX class

• over-current and earth fault – 10P

The rated short-time and rated short time current shall have a minimum rating equal to the

associated switchboard or ACCB.

The CT knee point should be calculated for a fault level based on the switchgear rating. Where

this is not practical due to CT physical dimensions, the maximum system fault level can be used

with a minimum 25% margin to allow for future increases in system fault levels.

8.5.4. Current transformers for metering Measurement CTs shall be of a class entirely suitable for the application as specified in

AS 60044.1 and the requirements of the National Electricity Rules.

RailCorp bulk supply feeders are class Type 2 for determining the applicable National Electricity

Rules requirements.




As a general guide the following are typical class of accuracy used in the RailCorp HV

distribution network:

• 0.5 class for general tariff metering such as supplies to shops, workshops and so on.

• 1.0 class for general measurement such as transducers and ammeters.

The measurement current transformers shall have the same ratio and rated continuous thermal

current as the associated protection CTs on the circuit.

See Appendix J for additional current transformer requirements applicable to bulk supply points.

8.5.5. Current transformer secondary wiring The following are requirements for the CT secondary wiring:

• All CT secondary wiring shall be provided with individual test links at the marshalling strip

within the respective low voltage compartment. The test links shall be Weidmuller SAKC10.

• CTs shall be earthed at one point and the earth point formed by using a proprietary cross

connection for the links being used. This single point earth shall be within the LV

compartment.

• Where multiple ratio CTs are used, the secondary wiring from all the CT taps shall be

terminated into the LV compartment to enable selecting the CT ratio within the LV

compartment.

• The CT wiring shall be connected to the associated protection relay (or revenue meter) by

means of a test block that allows isolation of the protection relay or revenue meter and

short-circuiting of the current transformer secondary. If the relay test blocks are not integral

with the relay enclosure then a test block shall be provided.

• The wiring shall be a minimum size of 2.5 mm2 and have an insulation rating of 0.6/1 kV.

Where 2.5 mm2 wiring is used it shall have a stranding of 50/0.25 mm.

• All wiring connections to the CT terminals and to the protection relay shall be made using

double grip ring type pre-insulated crimp lugs. Connections to terminals of protection relays

that a ring type lug will not physically fit shall be terminated with the manufacturers

recommended lug.

• Wiring identification shall be in accordance with Appendix K.

The CT secondary wiring insulation shall be coloured as detailed in Table 1.

Outdoor ACCBs can have black wiring from the CT terminals to the terminal block within the LV

compartment to allow for different orientation of the ACCB.




Table 1 - CT secondary wiring insulation colour

Phase Insulation colour

AØ red

BØ white

CØ blue

Neutral black

Refer to EP 00 00 00 15 SP Common Requirements for Electrical Power Equipment for details

of cable identification requirements.

8.6. Voltage transformers VTs shall be provided for all three phases and can either be a three-phase VT or three single-

phase VT.

VTs shall be manufactured and tested in accordance with AS 60044.2 Instrument transformers

– Part 2: Inductive voltage transformers. They shall have the same rated primary voltage as the

switchgear.

The number of secondary windings will depend on whether a residual protection class winding

or a metering class winding is required in addition to the protection class winding.

The voltage factor shall be 1.9 for 30 seconds.

Table 2 - VT specifications

Performance category

Rated voltage Accuracy class Rated burden (minimum) Note 1

Protection 110/√3 V 3P 50 VA

Metering 110/√3 V 0.5 50 VA

Note 1: The rated burden is required to be calculated for the specific location and

application.

The neutral point of the star connected primary shall be earthed. The neutral point of the star

connected secondary winding shall be brought out and connected to suitably insulated terminals

located in the LV compartment and earthed.

The VTs shall be protected by suitably rated ACCBs connected in the low voltage circuit as

close as possible to the transformer terminals.

HV fuse protection of VTs is not mandatory and is only required where recommended by the HV

switchboard manufacturer or manufacturer of the VT.

The requirement for a residual winding is dependent on the type of protection relay to be used.




See Appendix J for details on VT requirements for bulk supply points.

8.6.1. Voltage transformer secondary wiring The VT secondary wiring shall be coloured in accordance with the current transformer wiring

(see Table 1) with the exception of any open delta wiring, which shall be purple.

All wiring connections to CTs and to protection relays shall be made using double grip ring type

pre-insulated crimp lugs.

Terminal blocks for VT secondary wiring shall provide 4 mm sockets for the connection of test

equipment.

8.6.2. Voltage transformer alarms A three-phase, phase failure relay shall be connected to the star connected secondary winding

of the VT.

The phase failure relay shall provide a normally closed 'VOLTAGE TRANSFORMER FAIL'

alarm contact as well as visual indication.

The relay shall detect both undervoltage and negative phase sequence voltage unbalance on

the load side of the first ACCB connected to the secondary winding.

8.6.3. Voltage transformer supply to protection relays The VT supply to protection relays shall be connected to a dedicated ACCB for each protection

relay. The ACCB shall have a voltage free auxiliary contact that is connected to the SCADA

system to give a ‘FEEDER XXX DIRECTIONAL VOLTAGE FAIL' alarm.

8.6.4. Voltage transformer for 11 kV side of system transformers All 66/11 kV and 33/11 kV system transformers shall have a VT connected to the 11 kV side of

the transformer. The VT shall normally be located on the line side of the transformer 11 kV

ACCB on the 11 kV switchboard.

VTs shall be provided for all three phases and shall be single-phase VTs.

8.6.5. Voltage transformers for 66/33 kV system transformers All 66/33 kV system transformers shall have a VT connected to both the 66 kV and the 33 kV

side of the transformer. The VT shall be located on the line side of the transformer ACCB.

VTs shall be provided for all three phases and shall be single-phase VTs.




8.7. Auxiliary supply (dc) The majority of substations have an auxiliary supply of 125 V dc; other substations have a

supply of 50 V dc. The arrangement of the dc auxiliary supply is critical to the reliability of the

protection schemes.

8.7.1. Arrangement of auxiliary supply All ACCBs shall be individually supplied from the 50 V dc or 125 V dc distribution boards, with

individual supply for trip coil 1 and trip coil 2 and their associated circuitry.

In each ACCB, distinct control circuits and equipment shall be individually protected. The fuses

or circuit breaker shall be sized to ensure there is discrimination with the upstream protective

device.

The following is a list of typical ACCB circuits and equipment that would be individually

protected by fuses or circuit breakers:

• protection relays

• trip coil circuits

• close control circuit

• motor/spring charge circuits

• SCADA alarm and indication circuits

• dc/dc power supplies (for example, arc fault detection power supply, transducer power

supply)

• buszone protection schemes

See Appendix G for typical arrangement of ACCB auxiliary supply.

8.7.2. Requirement for two battery systems To ensure that integrity of the RailCorp HV distribution network is maintained when an auxiliary

supply fails, strategic substations are required to have two independent substation battery

systems.

See Section 8.2 for the criteria that defines a strategic substation.

The associated main distribution boards of the battery systems shall be capable of being

paralleled.

The two battery systems shall be of equal capacity and individually be rated for the full load and

duty cycle of the substation. Refer to EP 06 00 00 01 SP System Substation Battery & Battery

Charger for further details.




See Appendix B for specific requirements relating to protection schemes when two auxiliary

supplies are at a substation.

8.8. Protection relays and test blocks Protection relays and associated test blocks for use in the RailCorp HV electrical distribution

network require type approval. See Section 5 for further details.

All protection relays shall be flush mount and withdrawable. The auxiliary supply to the

protection relays shall be 125 V dc or 50 V dc as determined by the existing substation battery

or specified in the protection concept design.

Line differential protection relays shall be suitable for use with 1310 nm (single mode) fibre

optic.

The physical location of protection relays will depend on the type of switchgear installed.

The location should be on the low voltage compartment of the switchgear panels on indoor

switchgear or on dedicated protection panels for outdoor ACCBs, indoor 66 kV switchgear or

indoor switchgear that does not have the physical space for installing the protection relays.

The test block shall be located adjacent to the protection relay to which it is connected (right

side of protection relay).

The particular location requirements for specific relays and equipment are as follows:

• Transformer protection – differential relay, rectifier transformer frame leakage, MTA and

MTM relays shall be located on the primary protection panel.

• 66/11 kV and 33/11 kV transformers – neutral leakage relay shall be located on the 11 kV

switchgear panel.

• Buszone protection relay and associated multi-trip relay shall be located together on the

switchgear (same section) end panel.

• Bus cable tie protection relay and associated MTM relay shall be located together on either

of the associated bus-tie ACCB panels.

The standard test block wiring and input/output relay configuration are detailed in Appendix D

The labelling requirements for protection relays are detailed in Appendix H

8.9. ACCB close inhibit Where a protection operation results in an MTM relay being energised, the MTM relay shall

have normally closed contacts in the closing circuit of all the HV ACCBs that were tripped by the

MTM. This is applicable for all protection schemes.

System transformers and 11 kV/415 V transformers shall have a close inhibit contact in both the

primary and secondary ACCB closing circuits where fitted.




8.10. Protection alarms Every operation of a protection relay shall result in an individual alarm being sent to the SCADA

system and provide a local indication.

The alarm shall enable the electrical system operators to accurately identify the protection

scheme that has operated.

Refer to T HR EL 11001 TI SCADA Standard I/O Schedule for a detailed listing of SCADA

alarms.

8.11. Intertrip arrangements Optical fibre shall be used for the communication between protection relays of an intertripping

scheme.

The intertripping should be achieved utilising the line differential relays that have intertripping as

a function of the relay.

9. Specific equipment applications The protection requirements for specific equipment applications are detailed in Section 9.1

through to Section 9.10.

9.1. 132 kV feeders At the time of publication of this standard only one 132 kV feeder exists, which is a bulk supply

feeder. The protection requirements for a 132 kV bulk supply feeder are the same as detailed in

Table 3.

132 kV feeders other than bulk supply feeders are not envisaged in the future.

9.2. 33 kV and 66 kV feeders The protection requirements for 33 kV and 66 kV feeders are detailed in Section 9.2.1 through

to Section 9.2.6.

9.2.1. Standard protection schemes The schemes in Table 3 shall be provided for the protection of 33 kV and 66 kV feeders.




Table 3 – 33 kV and 66 kV feeder protection schemes

Protection scheme RailCorp network feeder Bulk supply feeder (see Note 1)

Primary protection Line differential Line differential and directional over-current and earth fault located in the RailCorp substation (looking towards supply point).

Backup protection Over-current and earth fault (may be directional if required by system configuration to achieve discrimination).

In accordance with the other electrical distributor policy.

Note 1: The exact protection requirements for bulk supply feeders can vary between

electricity distributors. TransGrid as an example require duplicate line differential

protection.

9.2.2. Primary protection All line differential schemes shall include communication circuit monitoring, which shall be

implemented as a function of the line differential relay.

9.2.3. Backup protection The backup protection on the feeder shall be an over-current and earth fault scheme, which

may be directional if required by system configuration to achieve discrimination.

This scheme shall operate by means of an ACCB and CTs that are not part of the primary

scheme.

9.2.4. Circuit breaker fail scheme The failure of an ACCB to open in response to a protection trip command shall be detected and

all possible sources of supply shall have their ACCBs tripped. A time delay of 0.2 seconds

should be provided to avoid nuisance tripping.

All ACCBs on the same busbar section as the failed ACCB shall be tripped by means of a multi-

trip relay. The buszone multi-trip relay shall be used for this purpose where fitted, otherwise the

multi-trip relay shall be an MTM relay for an indoor switchboard and an MTA relay for an

outdoor busbar.

The remote end ACCB for all the feeders on the busbar shall be tripped.

The protection relay that initiated the trip should provide the breaker fail function.

9.2.5. Location of current transformers The CTs should be located on the busbar side of the feeder ACCBs.




Where this is not practicable, the current transformers for feeder protection may be located on

the line side of the feeder ACCB. In this arrangement an intertrip shall be provided to trip the

feeder ACCB at the far end of the feeder whenever the local feeder ACCB is tripped.

See Section 8.11 for further details on intertripping.

See Appendix I for typical line differential arrangements.

9.2.6. Metering requirements Every feeder shall be provided with an ammeter and all bulk supply feeders shall be provided

with metering.

The metering on a bulk supply feeder shall be duplicated as follows:

• One set of metering for revenue checking by the operator and maintainer.

• Second set of metering that shall comply with the current National Electricity Rules, the

Service and Installation Rules of New South Wales and local electricity distributor. The

meter shall be connected to dedicated current transformers.

See Appendix J for specific current and VT requirements applicable to bulk supply points.

Details of the ammeter, metering and their connection are specified in the appropriate

switchgear standard.

9.3. 11 kV feeders The protection requirements for 11 kV feeders are detailed in Section 9.3.1 through to

Section 9.3.7.

9.3.1. Standard protection schemes The 11 kV network supplies a large variety of installations with varying degrees of operational

criticality. These installations range from underground stations, major signal boxes to minor

maintenance locations supplied from pole mounted transformers.

The criticality of the installation, accessibility of the 11 kV feeder and the fault level determines

the type of protection to be provided.

9.3.2. Primary protection See Section 8.2 for details of the definitions for determining if an 11 kV is critical and if the

primary protection needs to be a line differential scheme.

All line differential schemes shall include communication circuit monitoring, which shall be

implemented as a function of the line differential relay.




Where the primary protection scheme is not required to be a line differential scheme, the feeder

shall be protected with an over-current and earth fault scheme. The over-current and earth fault

scheme may be directional if required by system configuration to achieve discrimination.

9.3.3. Backup protection The primary protection on the feeder shall be backed up by an over-current and earth fault

scheme which may be directional if required by system configuration to achieve discrimination.

Where the primary protection is a line differential scheme, the backup over-current and earth

fault scheme can be located on the same ACCB panel; however the scheme shall operate by

means of a separate protection relay and ACCB trip coil.

Where the primary protection is not a line differential scheme, the backup over-current and

earth fault scheme shall operate by means of an ACCB and current transformers that are not

part of the primary scheme.

Where the primary protection is an over-current and earth fault scheme and is located on an

11 kV switchboard supplied directly from a transformer, a neutral leakage relay shall be used as

backup protection for 11 kV feeder earth faults.

The transformer primary over-current protection may be used to backup feeder over-current

protection. This is subject to the transformer over-current settings being suitable.

9.3.4. Sensitive earth fault Sensitive earth fault protection (SEF) shall be implemented in addition to earth fault protection

where the earth fault protection poses a high risk of not detecting a fallen overhead conductor

and the feeder is in a bushfire prone area as defined in SP D 79036 - Sydney Trains Electricity

Distribution Network Bushfire Risk Management Plan.

The scheme shall be implemented using a core balance CT which is installed around all three

conductors, with all cable screens looped back through the CT.

SEF can be implemented in the same protection relay as the over-current and earth fault

protection relay.

See Appendix E for details of the auto re-close requirements when a SEF scheme is in service.

9.3.5. Circuit breaker fail scheme The failure of an ACCB to open in response to a protection trip command shall be detected and

all ACCBs on the same busbar section as the failed ACCB shall be tripped by means of a multi-

trip relay. A time delay of 0.2 seconds should be provided to avoid nuisance tripping.

The multi-trip relay used to implement this may be the buszone multi-trip relay where fitted,

otherwise the multi-trip relay shall be an MTM relay for a switchboard.




If the feeders are protected by a line differential scheme then the appropriate remote end

ACCBs shall be tripped.

The protection relay that initiated the trip should provide this function.

9.3.6. Location of current transformers The CTs should be located on the busbar side of the feeder ACCBs.

Where this is not practicable, the current transformers for feeder protection can be located on

the line side of the feeder ACCB.

9.3.7. Metering requirements Every feeder shall be provided with an ammeter and all feeders that are a dedicated supply to

commercial premises (for example, train maintenance centres) shall be provided with metering

in accordance with the current National Electricity Rules and the Service and Installation Rules

of New South Wales where applicable.

Details of the ammeter, metering and their connection are specified in the appropriate TfNSW

switchgear standard.

9.4. High voltage busbars and bus-tie cables The protection requirements for HV busbars and bus-tie cables are detailed in Section 9.4.1

through to Section 9.4.5.

9.4.1. Primary protection for busbars All 33 kV and 66 kV indoor switchgear shall have buszone protection as the primary protection

for the busbar.

All 33 kV and 66 kV outdoor busbars shall have buszone protection as the primary protection

when the substation is not radially fed.

The requirement for buszone protection on radially fed outdoor busbars depends on the

criticality of the substation and whether a busbar fault will be detected and cleared with minimal

impact on the network. See Section 8.2 for criteria to determine whether a substation is critical.

The requirement for 11 kV indoor switchgear to have buszone protection depends on the

following location criteria:

• strategic location (see Section 8.2)

• location with high fault levels

• location where there is more than one busbar section




Where it can be demonstrated that the risk of a buszone fault on an 11 kV switchboard has

been negated by the design and construction of the switchboard, then buszone protection is not

required. The Lead Electrical Engineer, ASA shall approve this exemption.

The buszone protection for a HV switchboard can be implemented either as a high impedance

buszone protection scheme using CTs or as an arc fault detection scheme.

Arc fault detection schemes shall be type approved by the Lead Electrical Engineer, ASA as

part of the HV switchgear type approval.

Separate schemes shall be provided for each section of the busbar. All ACCBs on the

associated bus-section shall be tripped. Close inhibit shall also be implemented; see

Section 8.9 for details.

The tripping of ACCBs on an indoor switchboard shall be by means of a MTM relay. The

tripping of ACCBs on an outdoor busbar shall be by means of an MTA relay.

9.4.2. Primary protection for bus-tie cables All bus-tie cables interconnecting 11 kV, 33 kV and 66 kV indoor switchboards shall have high

impedance buszone protection as the primary protection.

The scheme shall be arranged to trip the ACCBs at both ends of the tie cable by means of a

MTM relay. Close inhibit shall also be implemented; see Section 8.9.

9.4.3. Backup protection for busbars and bus-ties The backup protection for a busbar shall be upstream over-current and earth fault protection.

Where the busbar directly interfaces with an electricity distributor then a local over-current and

earth fault protection can be the backup protection. This can be implemented in the same

directional protection relay that is looking towards the electricity distributor.

The backup protection for a bus-tie shall be a duplicate protection scheme where one of the

following applies:

• the switchboard directly interfaces with an electricity distributor

• the substation is a source of supply to underground stations or tunnels

otherwise, it shall be upstream over-current and earth fault protection.

9.4.4. Location of current transformers The current transformers for protection of the busbar should be located on the line side of all

ACCBs.

The current transformers for protection of the bus-tie cables should be located on the busbar

side of the tie ACCB.




Where the CTs for the feeder, bus-tie, or transformer circuits are not located on the busbar side

of the ACCB then:

• they shall be closest to the ACCB to have an overlap with the buszone scheme

• the buszone scheme shall also initiate tripping of the ACCBs at the far end of the feeder or

tie cable, or on the other winding of the transformer

9.4.5. Bus-tie circuit breaker fail scheme Where both primary and backup protection are installed, the failure of the ACCB to open in

response to a protection trip command shall be detected and the associated buszone MTM

relay shall be energised. A time delay of 0.2 seconds should be provided to avoid nuisance

tripping.

Only the busbar MTM associated with the ACCB that failed to open shall be energised.

9.5. Rectifier transformer and rectifier power cubicle The protection requirements for rectifier transformers and associated rectifier power cubicle are

detailed in Section 9.5.1 through to Section 9.5.5.

9.5.1. Primary protection The primary protection for the rectifier transformer and power cubicle shall be provided by an

over-current and earth fault relay. The relay shall also have the capability of programming

thermal protection for coordination with the rectifier.

The ACCB shall be tripped by means of a MTM relay for earth faults.

Refer to T HR EL 03001 ST Controls and Protection for 1500 V dc Rectification Equipment for

further detailed information on these requirements.

9.5.2. Backup protection The backup protection scheme for the rectifier transformer and power cubicle shall be provided

by a separate protection scheme, which is located in the same substation.

The protection shall be an over-current and earth fault relay. The relay shall also have the

capability of programming thermal protection for coordination with the rectifier.

The ACCB shall be tripped by means of a MTM relay for earth faults.

9.5.3. Rectifier transformer frame leakage Frame leakage protection shall be installed in addition to the primary and backup protection.

This protection shall monitor the current from the transformer tank to the substation earth

system.




A dedicated instantaneous relay and test block shall be installed in the same location as the

primary and backup protection relays for the rectifier transformer.

Refer to EL0283030 Substations – 33kV Transformer Frame Leakage - Arrangement for further

details.

9.5.4. Circuit breaker fail scheme The failure of the ACCB to open in response to a protection trip command shall be detected and

the associated buszone MTM relay shall be energised. A time delay of 0.2 seconds should be

provided to avoid nuisance tripping.

9.5.5. Protection interface requirements Refer to T HR EL 03001 ST for further detailed information on the protection interface

requirements and requirements for non-electrical protection devices associated with the rectifier

transformer and rectifier power cubicle.

9.6. System transformers All system transformers shall have transformer differential as the primary protection and

over-current and earth leakage as the backup protection.

Refer to the ASA transformer equipment specification for details of non-electrical protective

devices installed on the transformer.

The protection requirements for system transformers are detailed in Section 9.6.1 through to

Section 9.6.6.

9.6.1. Primary protection The transformer differential scheme shall be arranged to trip both the primary and secondary

ACCBs.

The tripping of the ACCBs shall be by means of a multi-trip relay. If the transformer is cable

connected on both the primary and secondary (terminals and bushings not exposed) then the

multi-trip relay shall be a MTM relay; otherwise it should be an MTA relay.

9.6.2. Backup protection Over-current and earth fault shall be provided as the backup transformer protection and shall

trip both the primary and secondary ACCBs by means of a multi-trip relay.

If the transformer is cable connected (terminals and bushings not exposed) then the multi-trip

relay shall be a MTM relay for earth faults.




Over-current protection shall trip the ACCBs by means of an MTA relay regardless of the HV

transformer connection configuration.

Three-phase over-current protection shall be provided on the low voltage side of the transformer

as backup protection to the outgoing feeder over-current protection.

9.6.3. Circuit breaker fail scheme The failure of an ACCB to open in response to a backup protection trip command shall be

detected and the associated buszone multi-trip relay energised. A time delay of 0.2 seconds


9.6.4. Neutral leakage On 66/11 kV and 33/11 kV system transformers, neutral leakage shall be provided as backup

protection to 11 kV feeder earth faults. The scheme shall trip both the primary and secondary

ACCB of the transformer by means of a MTA relay. The neutral leakage relay shall be located

on the 11 kV switchboard.

9.6.5. Non-electrical protection devices System transformers are fitted with non-electrical protection devices which interface with the

protection relays to trip the ACCBs as follows:

• Buchholz relays shall trip both the primary and secondary ACCBs by means of a MTM

relay

• pressure relief devices shall trip both the primary and secondary ACCBs by means of a

MTM relay

• temperature monitoring, first stage shall be an alarm and second stage shall trip both the

primary and secondary ACCBs by means of a MTM relay

The exact non-electrical protection device will depend on the type of transformer.

9.6.6. Location of current transformers The CTs for the differential protection should be located on the busbar side of both the primary

and secondary ACCBs. Where this is not practicable, the CTs for transformer protection can be

located on the transformer side of the transformer ACCB.

The current transformer for neutral leakage protection shall be located on the neutral to earth

connection on the transformer.




9.7. 11 kV / 415 V transformers supplied from ring main units All 11 kV distribution transformers (200 kVA and above up to 1 MVA) that are supplied by

means of an ACCB from a ring main unit (RMU) shall be protected by a protection relay.

Transformers less than 200 kVA shall be protected by fuses.

9.8. 11 kV / 415 V transformers supplied from SCADA controlled ACCBs The requirements detailed in Section 9.8.1 to Section 9.8.6 apply to 11 kV / 415 V transformers

supplied from SCADA controlled ACCBs, except those SCADA controlled ACCBs in a RMU.

9.8.1. Standard protection schemes All 11 kV transformers 1 MVA or greater in size shall have transformer differential as the primary

protection and over-current and earth leakage as the backup protection.

Transformers that are less than 1 MVA shall have over-current and earth leakage as the

primary protection.

Transformer differential schemes may be used on smaller transformers where required to

ensure that the transformer protection grades over the LV protection.

9.8.2. Primary protection The primary protection scheme shall trip both the primary and secondary ACCBs by means of a

multi-trip relay.

If the transformer is cable connected on both the primary and secondary (terminals and

bushings not exposed) then the multi-trip relay shall be a MTM relay; otherwise it should be an

MTA relay.

9.8.3. Backup protection Over-current and earth fault shall be provided as the backup transformer protection and shall

trip both the primary and secondary ACCBs by means of a multi-trip relay.

If the transformer is cable connected on both the primary and secondary (terminals and

bushings not exposed) then the multi-trip relay shall be a MTM relay; otherwise it should be an

MTA relay.

Over-current protection shall trip the ACCBs by means of an MTA relay regardless of the HV

transformer connection configuration.




The backup protection scheme is not required to detect faults on the LV winding of a distribution

transformer or the LV cables.

9.8.4. Circuit breaker fail scheme The failure of an ACCB to open in response to a backup protection trip command shall be

detected and the associated buszone multi-trip relay energised. A time delay of 0.2 seconds


9.8.5. Non-electrical protection devices Transformers are fitted with non-electrical protection devices which interface with the protection

relays to trip the ACCBs as follows:

• Buchholz relays shall trip both the primary and secondary ACCBs by means of a MTM

relay

• pressure relief devices shall trip both the primary and secondary ACCBs by means of a

MTM relay

• temperature monitoring, first stage shall be an alarm and second stage shall trip both the

primary and secondary ACCBs by means of a MTM relay

The exact non-electrical device depends on the type of transformer.

9.8.6. Location of current transformers The CTs for the differential protection should be located on the busbar side of both the primary

and secondary ACCBs. Where this is not practicable, the CTs for transformer protection can be

located on the transformer side of the transformer ACCB.

9.9. Harmonic filters The protection requirements for harmonic filters are detailed in Section 9.9.1 through to Section

9.9.14.

See Appendix L for a general connection diagram.

9.9.1. Primary protection The primary protection for the harmonic filter shall be provided by an over-current and earth

fault protection relay and two specialised harmonic filter protection relays for the protection of

the reactor and capacitor banks.

The auxiliary capacitor is not protected; instead it shall be rated conservatively to ensure that it

does not fail under any reasonable operating conditions.




Similarly, the damping resistor is not supplied with over-current protection as it shall be very

conservatively rated.

9.9.2. Capacitor bank protection The capacitor banks shall be protected by an over-current and earth fault protection relay to

detect filter bank internal short circuits and earth fault currents.

9.9.3. Phase undervoltage protection Phase undervoltage protection shall also be provided by the over-current and earth fault relay to

trip the harmonic filter ACCB. A timer relay shall be initiated to inhibit re-energisation of the

harmonic filter before the capacitors are discharged to a safe voltage.

9.9.4. Repetitive peak overvoltage protection Repetitive peak overvoltage protection shall be provided by a specialised harmonic filter

protection relay for the capacitor banks. This relay shall withstand a root mean square (rms)

sinusoidal voltage of 110% rated voltage at rated frequency for extended periods, or higher

voltages for shorter periods as described by the temporary overvoltage withstand curves in the

relevant ANSI and IEC recommendations.

9.9.5. Thermal over-current protection Thermal over-current protection shall be provided by a specialised harmonic filter protection

relay to protect the harmonic filter components from excessive temperature rise as limited by

adjustable threshold settings on the relay.

9.9.6. Unbalance protection Protection of the capacitor banks is achieved mainly by means of unbalance protection. The

unbalance protection shall be provided by two specialised harmonic filter protection relays to

protect the capacitor banks that are connected in a double star point and H-bridge

configurations.

The unbalance protection shall be required to raise an alarm in the event of a failure of one or

more capacitor elements and to trip the ACCB in the event of a failure of two or more elements.

The protection shall prevent overvoltage stressing of capacitor units.

9.9.7. Double star point unbalance protection Double star point unbalance protection shall be provided by a specialised harmonic filter

protection relay to monitor the flow of current between the double star points of the harmonic

filter capacitor banks in the event of component failure.




The time delay for trip shall be the shortest possible to avoid serious damage in case of element

breakdown.

9.9.8. H-bridge unbalance protection H-bridge unbalance protection shall be provided by a separate specialised harmonic filter

protection relay for each phase of the capacitor bank.

9.9.9. Backup protection Backup protection shall be provided by an upstream over-current and earth fault protection

relay.

9.9.10. Breaker fail scheme The failure of the ACCB to open in response to a protection trip command shall be detected and

the associated buszone MTM relay shall be energised. A time delay of 0.2 seconds should be

provided to avoid nuisance tripping.

The protection relays should provide this function.

9.9.11. Location of current transformers The preferred locations of the protection current transformers (CTs) are as follows:

• over-current and earth fault – busbar side of the ACCB

• thermal over-current – busbar side of the ACCB

• repetitive peak overvoltage (shared the same CT as thermal over-current) – busbar side of

the ACCB

The preferred locations of the unbalance protection CTs in the capacitor banks are as follows:

• H-bridge unbalance – reference A phase CT on feeder side of ACCB (CTs on the H-bridge)

• Double star unbalance – reference A, B and C phase CTs on feeder side of ACCB (CTs on

the star point)

9.9.12. Voltage transformer A VT shall be provided for all three phases and can either be a three-phase VT or three single-

phase VTs.

VTs shall be connected to an over-current and earth fault protection relay to provide phase

undervoltage protection.

The VTs should have an accuracy class 3P and rated burden 45 VA or 50 VA. A dedicated VT

may not be required and where available, inputs from the existing bus section VT may be used.




9.9.13. Metering requirements The harmonic filter shall be provided with a current transformer, a current transducer and an

ammeter for local and remote metering only on B-phase.

9.9.14. Access interlock To prevent personnel from accessing the harmonic filter prior to the capacitors being discharged

to less than 50 V ac, a timer circuit and key lock switch arrangement shall be employed. The

timer circuit is also used to inhibit re-closure of the harmonic filter HV ACCB after an open or trip

operation.

The timer setting shall be based on the time constant of the filter plus an appropriate safety

margin to allow the capacitors to discharge to less than 50 V ac.

If the mechanical key lock is not available, then electro-mechanical interlocking shall be

employed between electro-mechanical key lock release and a timer relay.

Additional safety requirements may be required to ensure that the capacitor banks are

discharged to less than 50 V ac before releasing the locks.

The interlock shall be implemented on the harmonic filter switchgear panel and shall not rely on

the SCADA system to inhibit control of the harmonic filter HV ACCB during capacitor discharge.

9.10. Protection SCADA alarms Protection alarms are a critical piece of information that shall be conveyed to the SCADA

system for use by the electrical system operator and recorded as engineering information.

The protection SCADA alarm requirements are detailed in T HR EL 11001 TI.

See Appendix F for details on protection alarms that are required to be hardwired.

10. Voltage and current transducers Transducers that are to be used to provide the SCADA system with current and voltage

information relating to the HV network shall be in accordance with the requirements of T HR EL

11004 ST Electrical SCADA Interface.

Current transducers shall be connected to metering class CT and shall not be connected to

protection CTs.




Appendix A ACCB trip coils Table 4 details the protection scheme and associated ACCB trip coil to which the protection

relay is connected. The relevant section in this standard specifies whether the trip is by means

of a multi-trip relay and the associated type.

An approved protection concept design for individual locations documents the specific

requirements for that location.

See Section 9.2.1 for additional requirements relating to breaker fail schemes and supply

points.

Table 4 – ACCB trip coil allocation

Equipment Protection scheme Trip coil number Notes

Feeder protection Line differential 1

Over-current and earth fault

2 c

Intertrip 1

Buszone and bus-tie Busbar protection 2 a

Cable bus-tie protection

1 b

66/33 kV system transformers

Differential 1 d, e

66 kV over-current and earth fault

2 e

33 kV over-current and earth fault

2 e

Tx overpressure, Buchholz, tx winding temp

1 e

66/11 kV and 33/11 kV system transformers

Differential 1 d, e

33 kV over-current 2 e

Neutral leakage 2 e

11 kV over-current 2 e

Tx overpressure, Buchholz, tx winding temp

1 e

Harmonic filter Over-current and earth fault

1

Phase undervoltage 1

Repetitive peak overvoltage

2

Thermal over-current 2

Double star point unbalance

2




Equipment Protection scheme Trip coil number Notes

H-bridge unbalance 2

11 kV/415 V transformers

Differential 1 e, g

Over-current 2 c, g

Rectifier transformers (primary protection)

Instantaneous over-current

1 f

Earth fault 1 f

Rectifier transformers (backup protection)

Instantaneous over-current

2 f

Earth fault 2 f

Rectifier transformer MTM and frame leakage

1

Notes:

a) The operation of the buszone protection energises a multi-trip relay, which trips all

ACCBs on the section of the busbar. The trip coil number applies to all ACCBs that are

tripped on the associated busbar section. See Section 9.4 for requirements on MTM or

MTA trip.

b) When there is duplicate protection on the bus-tie cable the duplicate scheme shall trip

the ACCBs by means of trip coil 2 (by means of an MTM).

c) If there is no differential protection, then the over-current protection shall trip by means

of trip coil 1.

d) Trip coil number applies to both ACCBs (for example, 33 kV and 11 kV, 66 kV and

33 kV).

e) See Section 9.6 for requirements on MTM or MTA trip.

f) See Section 9.6 for requirements on MTM or MTA trip.

g) See Section 9.8 for requirements on MTM or MTA trip.




Appendix B Two battery systems (125 V dc) – allocation of battery to protection equipment

When allocating the battery for substations with two battery systems the principles in this

appendix should be applied.

The battery allocation should be determined with the substation and HV networks in the normal

operating state.

See Appendix G for details of typical auxiliary supply arrangement to HV ACCBs. These

diagrams illustrate the principle; however, detailed design is required to ensure the following

principles are applied:

• The loss of one battery should not result in the loss of all the primary protection schemes

on similar equipment.

• The protection relay should be supplied from the same battery as the HV ACCB trip coil

that it energises. See Appendix A for details on protection and associate HV ACCB trip coil.

This is not generally applicable to buszone and bus-tie protection schemes.

• HV feeders - The battery should be alternated to ensure that not all feeder primary

protection is sourced from the one battery.

• Busbar protection - The battery should be alternated to buszone protection schemes.

• Rectifiers – The battery should be alternated to ensure that not all rectifier primary

protection is sourced from the one battery.

• Systems transformers – where there are multiple system transformers the battery should

be alternated to ensure that not all system transformer primary protection is sourced from

the one battery.

• HV bus-tie - The battery should be alternated to ensure that not all bus-tie protection is

sourced from the one battery.

• 1500 V DCCBs – The battery should be allocated to consider operational impacts.

• SCADA alarms – The supply to SCADA alarms shall be from battery 1.

In the case of two battery systems, the equipment should be connected across the two battery

systems to obtain balanced loads as close as possible.




Appendix C Protection relay identification Device numbers and functions should be in accordance with IEEE C37.2: 2008 Electrical Power

System Device Function Numbers, Acronyms, and Contact Designations. The detailed

implementation shall be as set out in accordance with Table 5.

Table 5 – Protection relay identification

Relay identifier Description

27/HF Phase undervoltage protection

49/HF Thermal over-current protection

50/L Instantaneous over-current relay (feeder)

50/T Instantaneous over-current relay (transformer)

50/T1 Instantaneous over-current relay – Backup (transformer)

51/L Inverse time over-current relay

59/HF Repetitive peak overvoltage protection

60/HF Double star point unbalance protection

60/HF H-bridge unbalance protection

63 Buchholz relay

64 Instantaneous earth fault relay

64FL Transformer frame leakage relay

67 Directional over-current relay

67/L Directional over-current relay (feeder)

87/B Differential protective relay (busbar – high impedance)

87/BT Differential protective relay (bus-tie cable – high impedance)

87/L Differential protective relay (feeder - line differential scheme)

87/T Differential protective relay (transformer)

MTA Multi trip automatic reset relay

MTM Multi trip manual reset relay

SRR Send receive relay

TBK1,2 Test block

TCS Trip circuit supervisory relay

SEF Sensitive earth fault




Appendix D Standard test block wiring and input/output relay configuration

The test block, protection relay input and output configurations in this appendix are provided to

ensure consistency with the programming of numerical relays, the testing procedures for

periodic maintenance and the production of standard designs.

The configurations do not determine the requirement for a particular protection function, but

detail the test block connections and output or input relay if that function is required to be

implemented.

To connect alarms by means of the test block or to connect spare output relays to the test block

is not a general practice. The test block shall be located adjacent to the protection relay it is

associated with.

Where the alarms are conveyed by the serial communications of the relay it is not required to

program the relay output contacts for the same alarms.

Any deviations from the standard configuration shall be approved by the Lead Electrical

Engineer, ASA.




D.1. Line differential protection

Line Differential Protection

MiCOM P541 & P543 Relay

Relay MMLG01 Incoming Supplies

Relay 3 contact 2 x 1 Trip +ve

Relay 3 contact 4 x 3 Line Diff Trip

Va 6 x 5 Va

Vb 8 x 7 Vb

Vc 10 x 9 Vc

Vn 12 x 11 Vn

Terminal J2 14 II 13 + 125 V dc aux supply

Terminal J1 16 x 15 - 125 V dc aux supply


Relay 8 contact 20 x 19 CB Fail trip

Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Spare

Relay 2 Spare

Relay 3 Line Differential Trip

Relay 4 – Relay 7 Spare

Relay 8 Breaker Fail Trip


Terminal 36 & 37: Relay Fail Alarm

Input Relays:

L1 Intertrip Initiate

L2 TCS Input

L3 Feeder ACCB status (52a contact)

L4 Feeder Earth Switch Status (if required)

L5 Feeder ACCB status (52b contact)

L6 - L16 Spare





MiCOM P521 Relay



Relay 1 contact 4 x 3 Line Diff Trip

Spare 6 x 5 Spare

Spare 8 x 7 Spare

Spare 10 x 9 Spare

Spare 12 x 11 Spare

Terminal 33 14 II 13 + 125 V dc aux supply

Terminal 34 16 x 15 - 125 V dc aux supply



Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Line Differential Trip

Relay 2 TCS Alarm

Relay 3 Line Differential Alarm

Relay 4 Comms Fail Alarm

Relay 5 Spare

Relay 6 Breaker Fail Alarm

Relay 7 Spare



Input Relays:

L 1 Intertrip Initiate

L2 TCS Input

L3 – L5 Spare





Siemens 7SD610 Relay


Relay BO4 contact 2 x 1 Trip +ve

Relay BO4 contact 4 x 3 Line Diff Trip

Spare 6 x 5 Spare

Spare 8 x 7 Spare


Relay BO5 contact 12 x 11 Intertrip Trip

Terminal F2 14 II 13 + 125 V dc aux supply

Terminal F1 16 x 15 - 125 V dc aux supply


Relay BO3 contact 20 x 19 CB Fail trip

Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Input Relays:

BI1 - BI4 Spare

BI5 - TCS input

BI6 – ACCB status

BI7 – IT initiate send

Output Relays:

BO1 Line Diff Trip alarm

BO2 Comms fail alarm

BO3 Remote ACCB indication

BO4 Line Differential & Intertrip Receive Trip

BO5 Breaker Fail Trip

Note:

At some locations alarms are by means of DNP3.0 communication.




D.2. Feeder over-current and earth fault protection

Feeder DOC & DE Protection

MiCOM P127 Relay



Relay 1 contact 4 x 3 Trip

Va 6 x 5 Va

Vb 8 x 7 Vb

Vc 10 x 9 Vc

Vn 12 x 11 Vn





Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Over-current & Earth Fault Trip

Relay 2 TCS Alarm

Relay 3 Spare

Relay 4 Over-current Alarm

Relay 5 Earth Fault Alarm


Relay 7 Intertrip Send (if required)



Input Relays:

L1, L2, L3 Spare

L4 TCS

L5, L6, L7 Spare




Feeder DOC & DE & Sensitive Earth Fault Protection

MiCOM P127 Relay

Test Block 1



Relay 1 contact 4 x 3 Trip (O/C, E/F & DSEF)

Va 6 x 5 Va

Vb 8 x 7 Vb

Vc 10 x 9 Vc

Vn 12 x 11 Vn

Test Block 2 – Term. 13 14 II 13 + 125 V dc aux supply

Test Block 2 – Term. 15 16 x 15 - 125 V dc aux supply



Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Test Block 2


Spare 2 x 1 Spare

Spare 4 x 3 Spare

Spare 6 x 5 Spare

Spare 8 x 7 Spare

Spare 10 x 9 Spare

Spare 12 x 11 Spare

Terminal 33 14 II 13 Test Block 1 – Term. 14

Terminal 34 16 x 15 Test Block 1 – Term. 16

Spare 18 x 17 Spare

Spare 20 x 19 Spare

Spare 22 x 21 Spare

Spare 24 x 23 Spare

DSEF 26 x 25 DSEF

In 28 x 27 In




Output Relays:

Relay 1 O/C, E/F & DSEF Trip

Relay 2 TCS Alarm

Relay 3 DSEF Alarm




Relay 7 Spare



Input Relays:

L1, L2, L3 Spare

L4 TCS

L5, L6, L7 Spare




D.3. Rectifier protection Rectifier Protection

MiCOM P14N Relay



Relay 1 contact 4 x 3 Over-current Trip


Relay 3 contact 8 x 7 Earth Fault Trip

Spare 10 x 9 Spare

Spare 12 x 11 Spare





Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay Healthy Relay watchdog

Relay Failed Spare

Relay 1 Over-current Trip

Relay 2 Spare

Relay 3 Earth Fault Trip (to MTM)

Relay 4 Spare

Relay 5 Earth Fault Trip to PLC if required

Relay 7 Spare


Relay 9 - 12 Spare


Input Relays:

L1 to L8 Spare

L9 TCS

L10 & L11 Spare




Rectifier Protection

MiCOM P127 Relay






10 x 9 Spare

12 x 11 Spare





Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Not used (see Note 1)

Relay 2 TCS Alarm

Relay 3 Earth Fault Trip (to MTM)

Relay 4 Over-current and Earth Fault Alarm

Relay 5 Earth Fault Trip (to PLC)





NOTE 1: The breaker fail function of this relay is initiated internally by Relay 1, hence

Relay 1 is programmed to be energised for either an OC or EF trip.

Input Relays:

L1, L2, L3 Spare

L4 TCS

L5 Timer initiate (from Rectifier MTM)




L6, L7 Spare




Rectifier Transformer Frame leakage Protection

MCAG 14 Relay


MCAG trip contact 2 x 1 Trip +ve

MCAG trip contact 4 x 3 Trip

Spare trip contact 6 x 5 Spare trip contact


Spare 10 x 9 Spare

Spare 12 x 11 Spare

Spare 14 II 13 Spare

Spare 16 x 15 Spare

Spare 18 x 17 Spare

Spare 20 x 19 Spare

Ifl 22 x 21 Ifl

Ifl 24 x 23 Ifl

Spare 26 x 25 Spare

Spare 28 x 27 Spare

Relay Contacts:

Contacts terminals 1 & 3: trip

Terminals 2 & 4: Trip alarm




D.4. System transformer protection HV/LV kV Transformer Differential Protection

MiCOM P632 Relay

TEST BLOCK 1


Tx Diff trip contact 2 x 1 MVAJ Trip +ve

Tx Diff trip contact 4 x 3 MVAJ Trip

Spare 6 x 5 Spare

Spare 8 x 7 Spare

Spare 10 x 9 Spare

Spare 12 x 11 Spare

Test Block 2 – Term. 13 14 II 13 + 125V dc Aux Supply

Test Block 2 – Term. 15 16 x 15 - 125V dc Aux Supply

HV CBFail contact 18 x 17 Trip +ve (HV panel)

HV CBFail contact 20 x 19 HV CBFail Trip

Ia (HV CT input) 22 x 21 Ia (HV CT)

Ib (HV CT input) 24 x 23 Ib (HV CT)

Ic (HV CT input) 26 x 25 Ic (HV CT)

Io (HV CT input) 28 x 27 Io (HV CT)




TEST BLOCK 2


AUX TRIP CONTACT (see Notes 2 & 4)

2 x 1 MVAJ Trip +ve

AUX TRIP CONTACT (where required)

4 x 3 MVAJ Trip

Spare 6 x 5 Spare

Spare 8 x 7 Spare

Spare 10 x 9 Spare

Spare 12 x 11 Spare

P632 Aux Supply input 14 II 13 Test Block 1 – Term. 14

P632 Aux Supply input 16 x 15 Test Block 1 – Term. 16

LV CBFail contact (where required)

18 x 17 Trip +ve (LV panel)

LV CBFail contact (where required)

20 x 19 LV CBFail Trip

Ia (LV CT input) 22 x 21 Ia (LV CT)

Ib (LV CT input) 24 x 23 Ib (LV CT)

Ic (LV CT input) 26 x 25 Ic (LV CT)

Io (LV CT input) 28 x 27 Io (LV CT)

OUTPUT RELAYS (P632):

K901 TX DIFFERENTIAL TRIP (Note 4) K902 RELAY WATCHDOG K903 HV CBFAIL BACKTRIP K904, K905, K906, K907, K908 Spare

K701 TX & TAP CHANGER AUX TRIP (where applicable, see Notes 2 & 4) K702 Spare K703 LV CBFAIL BACKTRIP (where required) K704 Spare K705 Spare K706 Spare K707 Spare K708 Spare

Note: All relay alarms except Watchdog by means of Serial Communications (DNP3.0)

OPTO INPUTS (P632) (where applicable, see Note 2):

U901 TAP CHANGER BUCHHOLZ OIL SURGE OPERATION U902 TAP CHANGER PRESSURE SWITCH U903 TAP CHANGER BUCHHOLZ GAS ALARM




U904 TAP CHANGER LOW OIL

U701 TX BUCHHOLZ OIL SURGE OPERATION U702 TCS U703 TX WINDING TEMPERATURE U704 TX BUCHHOLZ GAS OPERATION U705 TX LOW OIL OR TX OIL TEMPERATURE U706 TX PRESSURE SWITCH

Note 1: All alarms except Relay Watchdog are to be by means of serial

communications. In cases where serial communications are not achievable, an

amended Test Block & I/O Wiring Configuration will be attached to the Protection

Concept Design.

Note 2: Inputs allocation shown above is a typical list. Some Tx & Tap Changer

inputs may not be required depending on the type and model of the transformer

available on site. Where a different auxiliary operation required is not listed above,

please use next available spare P632 input and inform the Electrical Protection

Systems Engineer for relay setting.

Note 3: If Test Block 2 is not required, terminals 14 & 16 of Test Block 1 will be wired

into P632 Aux Supply Input.

Note 4: If Transformer Differential trips by means of the MTM, then transformer and

tap changer auxiliary trips are to be combined with transformer differential trip through

output relay K901.




Transformer Protection

MiCOM P127 Relay






Spare 10 x 9 Spare

Spare 12 x 11 Spare





Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Not used (see note 1)

Relay 2 TCS Alarm

Relay 3 Earth Fault Trip







Input Relays:

L1, L2, L3 Spare

L4 TCS

L5, L6, L7 Spare

Note 1: The breaker fail function of this relay is initiated internally by Relay 1, hence

Relay 1 is programmed to be energised for either an over-current or earth fault trip.




However it is not connected externally as an over-current trip is require to energise an

MTA relay and the earth fault trip is required to energise an MTM relay.




Transformer Protection - Over-current & Neutral Leakage (11kV side)

MiCOM P127 Relay





Relay 3 contact 8 x 7 Neutral Leakage Trip

In 10 x 9 In

In 12 x 11 In





Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Spare

Relay 2 TCS Alarm

Relay 3 Neutral Leakage Trip (to MTA relay)


Relay 5 Neutral Leakage Alarm





Input Relays:

L1, L2, L3 Spare

L4 TCS

L5, L6, L7 Spare




D.5. Buszone and bus-tie protection Buszone & bus-tie Protection

MCAG34 Relay


MCAG trip contact 2 x 1 Trip +ve

MCAG trip contact 4 x 3 Trip



Spare 10 x 9 Spare

Spare 12 x 11 Spare

Spare 14 II 13 Spare

Spare 16 x 15 Spare

Spare 18 x 17 Spare

Spare 20 x 19 Spare

Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

AØ contacts terminals 1 & 3: trip


BØ contacts terminals 5 & 7: trip


CØ contacts terminals 9 & 11: trip


Note:

AØ, BØ & CØ trip contacts are connected in parallel at the relay terminals.




Bus-tie Protection (Backup differential)

MiCOM P127 Relay



Relay 1 contact 4 x 3 Differential Trip


Relay 7 contact 8 x 7 CBFail Trip Section X

Spare 10 x 9 Spare

Spare 12 x 11 Spare




Relay 8 contact 20 x 19 CBFail Trip Section Y

Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Differential Trip

Relay 2 TCS Alarm

Relay 3 Differential Trip AØ Alarm

Relay 4 Differential Trip BØ Alarm

Relay 5 Differential Trip CØ Alarm

Relay 6 CBFail Alarm

Relay 7 CBFail Trip Section X

Relay 8 CBFail Trip Section Y


Input Relays:

L1, L2, L3 Spare

L4 TCS

L5 Timer initiate

L6, L7 Spare




D.6. Harmonic filter protection Harmonic Filter Protection: Double-Star Point Unbalance Protection, Repetitive Peak

Overvoltage, Thermal Over-current

RLC04 RELAY 1

Relay 1 MMLG01 Incoming Supplies

Trip contact (Term. 10) 2 x 1 Trip +ve

Trip contact (Term. 12) 4 x 3 RPOV, ThOC & DSU trip

Spare 6 x 5 Spare

Spare 8 x 7 Spare

CT input (Term. 28) 10 x 9 Icap (double star unbalance CT)

CT input (Term. 27) 12 x 11 Icap (double star unbalance CT)

Aux input (Term. 5) 14 II 13 + 125 V dc aux supply

Aux input (Term. 7) 16 x 15 - 125 V dc aux supply

CBFail trip contact (Term. 17) 18 x 17 Trip +ve

CBFail trip contact (Term. 19) 20 x 19 CBFail trip

CT input 1 (Term. 22) 22 x 21 TBK 2 (Term. 11)

CT input 2 (Term 24) 24 x 23 Ib (Line CT)

CT input 3 (Term 26) 26 x 25 Ic (Line CT)

CT inputs 4 (Term. 21,23, 25) 28 x 27 Io (Line CT)

Output Relays:

Relay K1 Repetitive Peak Overvoltage, Thermal Over-current & Double

Star Unbalance Trip

Relay K2 Spare

Relay K3 Spare

Relay K4 Spare

Relay K5 Breaker Fail Trip

Relay K6 RLC04 Relay 1 Fail Alarm

Note: All alarms except the watchdog are to be serial linked (Modbus).

Input Relays:

Input 1 Spare




Harmonic Filter Protection: H-Bridge Unbalance Protection

RLC04 Relay 2

Relay 2 MMLG01 Incoming Supplies

Trip contact (Term. 10) 2 x 1 Trip +ve

Trip contact (Term. 12) 4 x 3 HBU trip

CT input (Term. 23) 6 x 5 Ia- (H-Bridge A phase CT)

CT input (Term. 25) 8 x 7 Ib- (H-Bridge B phase CT)

CT input (Term. 27) 10 x 9 Ic- (H-Bridge C phase CT)

CT input (Term. 21) 12 x 11 TBK 1 (Term. 21)

Aux input (Term. 5) 14 II 13 + 125 V dc aux supply

Aux input (Term. 7) 16 x 15 - 125 V dc aux supply

CBFail contact (Term. 17) 18 x 17 Trip +ve

CBFail contact (Term. 19) 20 x 19 CBFail timer initiate to P127 (27/51/HF) relay

CT input 1 (Term. 24) 22 x 21 Ia+ (H-Bridge A phase CT)

CT input 2 (Term. 26) 24 x 23 Ib+ (H-Bridge B phase CT)

CT input 3 (Term. 28) 26 x 25 Ic+ (H-Bridge C phase CT)

CT input 4 (Term. 22) 28 x 27 Ia+ (11 kV A phase line CT)

Output Relays:

Relay K1 H-BRIDGE Unbalance Trip

Relay K2 Spare

Relay K3 Spare

Relay K4 Spare

Relay K5 Trip – Breaker Fail Timer Initiate to P127 (27/51/HF) Relay, Input L5

Relay K6 RLC04 Relay 2 Fail Alarm

Note: All alarms except the watchdog are to be serial linked (Modbus).

Input Relays:

Input 1 Spare




Harmonic Filter Protection: Over-current & Earth Fault Protection and Undervoltage Protection

P127 Relay



Relay 1 contact 4 x 3 Over-current and earth fault and phase undervoltage trip

VT input 1 (Term. 69) 6 x 5 Va

VT input 2 (Term. 71) 8 x 7 Vb

VT input 3 (Term. 73) 10 x 9 Vc

VT input 4 (Term. 70, 72, 74) 12 x 11 Vo




Relay 8 contact 20 x 19 Breaker fail trip

Ia 22 x 21 Ia

Ib 24 x 23 Ib

Ic 26 x 25 Ic

Io 28 x 27 Io

Output Relays:

Relay 1 Over-current & Earth Fault and Phase Undervoltage Trip




Note: All alarms except the watchdog are to be serial linked (DNP3.0)

Input Relays:

Input L1 Spare

Input L2 Spare

Input L3 Spare

Input L4 TCS

Input L5 Timer initiate from RLC04[2]

Input L6 Spare

Input L7 Spare




Appendix E Auto re-close on high voltage feeders

This appendix provides the re-closure guideline for HV feeders on the RailCorp HV distribution

network. The operator and maintainer can develop and vary re-closure policy from this appendix

based on a risk analysis.

In general, HV feeders have one auto re-close in five seconds by SCADA (that is, the master

station initiates the auto re-close if all the requirements are met).

This policy applies to the following:

• 11 kV, 33 kV and 66 kV feeders that are entirely aerial lines

• a feeder that is partially cable and partially aerial line is treated as an aerial line

• where an aerial feeder is located outside the rail corridor, the auto re-close shall be based

on a risk assessment

Supply point feeders, feeders that are entirely cable and feeders with SEF protection shall not

have auto re-close implemented.

During periods of total fire ban, the auto re-close is inhibited on HV feeders that traverse areas

that are considered to be a bush fire risk in accordance with SP D 79036 - Sydney Trains

Electricity Distribution Network Bushfire Risk Management Plan. This is a master station

function initiated by the electrical system operator. Auto re-close is also automatically inhibited

for 10 minutes after a close control is initiated by the electrical system operator.




Appendix F Implementation of SCADA alarms and control

The SCADA alarms and control to and from equipment can be implemented by hard wiring or

using a high-level interface such as a serial link.

Numerical protection relays can be used to convey the information by using discrete output

relays or by means of serial links. However, certain information is critical for system operation

and shall be independent of the protection relay or communication link to the RTU.

The following list details the SCADA alarms and control that shall be hard wired to the RTU:

• ACCB control (both open and close)

• ACCB indication (both open and closed)

• ACCB DISCONNECTOR/ISOLATOR indication (all positions)*

• EARTH SWITCH indication (both open and closed)*

• protection relay watchdog alarms

• TCS where provided by a dedicated TCS relay

• tapchanger control

• analogues (current and voltage)

• phase failure relay

Note:

* If all circuit breakers on a switchboard are not fitted with numerical relays having

adequate RS485 communications to the RTU.




Appendix G Typical ACCB auxiliary supply arrangement

Figure 1 and Figure 2 provide detail on the typical arrangement of dc auxiliary supply to HV

ACCBs.

Both Figure 1 and Figure 2 show the positive fuse only. The fuse in the negative has not been

shown for clarity. The arrangement is also applicable when circuit breakers are used instead of

fuses.

Where two batteries are present in a substation the protection concept will detail the exact

arrangement for the dc auxiliary supply.

In two battery locations, where a HV panel has two 125 V dc submains, the submains are

required to be installed in separate diverse routes.

Figure 1 – Typical arrangement for dc auxiliary supply to HV ACCB for a substation with one battery.




Figure 2 – Typical arrangement for dc auxiliary supply to HV ACCB for a substation with two batteries.




Appendix H Protection labelling guidelines The rules in Section H.1 to Section H.5 apply to the labelling of protection relays and associated

auxiliary relays.

H.1. Location of labels Labels should be located directly above the relay. If this is not possible, then they should be

located directly below the relay.

H.2. Colour of labels All labels for protection relays shall have black writing on a yellow background.

All auxiliary relays (such as multi-trip relays) shall have black writing on a white background.

H.3. Format The following are the formatting requirements for labels:

• To keep the length of labels to a minimum, abbreviations shall be used for the protection

functions. The valid abbreviations are detailed in Table 6.

• All labels should be in CAPITALS (except for abbreviations such as ‘Tx’ and ‘kV’).

• The description of equipment shall be consistent with terminology as used in the ac

operating diagrams. This is summarised below:

o FEEDERS: ‘Feeder ID’

Where ‘Feeder ID’ is the unique three digit identification assigned to each HV feeder.

o TRANSFORMERS: ‘Unit ID’ + ‘voltage ratio’ + ‘Tx’

Where ‘Unit ID’ is the identification given where there are multiple transformers (such

as No.1, No.2, and so on) ‘voltage ratio’ is the voltage ratio of the transformer usually

expressed in kV (for example, 33/11kV, 66/33kV).

o RECTIFERS: ‘Unit ID’ + ‘RECTIFIER’

Where ‘Unit ID’ is the identification given where there are multiple rectifiers (such as

No.1, No.2, and so on).




H.4. Content FIRST LINE OF LABEL:

The following sequence should be used to construct a label:

a. equipment being protected or monitored or both

for example, No.1 RECTIFIER, BUS ZONE, 792, No.2 33/11kV Tx

b. type of protection

for example, DOC & DE RELAY, LINE DIFF, CURRENT CHECK, AØ DOC RELAY, AØ

OC RELAY, FL RELAY, Tx OC RELAY, Tx DIFF RELAY

c. make of relay in brackets

for example (P543), (P521), (P127), (MCAG34), (P632)

d. pointer to relay (if needed)

for example, ↑, ↓

H.5. Examples of labels The following are examples of labels:

• 798 DOC & DE RELAY (P127)

• 798 PW RELAY (P521)

• ↑ No.1 RECT IOC & IE RELAY (MCAG33)

• No.1 RECT IOC & IE BACKUP RELAY (P127)

• TRIP CCT 1 TCS RELAY (1TM10)

• No.1 33/11kV TxDIFF RELAY (P632)

• No.1 33/11kV Tx OC & E RELAY (P127)

• 1-2 BZT RELAY (MCAG34)

• ↓1-2 BZT MTM RELAY (MVAJ13)

• No.1 33/11kV Tx MTA RELAY (MVAJ11)

• No.1 SECTION BZ MTM RELAY (MVAJ13)

• 877 ENERGY METER (Mk6E)

• HF OC&E UV RELAY




Table 6 - Protection function abbreviation

Protection function Abbreviation

Arc Detection AD

Buchholz B

Breaker Fail BF

Blocking Relay BRly

Backup BU

Buszone BZ

Buszone Tie BZT

Directional Earth Fault DE

Directional Instantaneous Over-current DIOC

Directional Over-current DOC

Earth Fault E

DCCB Frame Leakage FLDC

AC Frame Leakage FL

Rectifier Frame Leakage FLR

Instantaneous Earth Leakage IE

Intelligent Gas Information System IGIS

Intelligent Light Information System ILIS

Instantaneous Over-current IOC

Intertrip IT

Instantaneous & Time Delay Over-current ITOC

Line Differential LD

Multi Trip Relay – Automatic Reset MTA

Multi Trip Relay – Manual Reset (Hand) MTM

Neutral Leakage NL

Over-current OC

Low Oil LO

Over-current & Residual Earth Fault Inverse Time ORET

Pressure Switch PS

Pilot Wire PW

Dc Reverse Current RC

Transformer Differential TxDIFF

Transformer Winding Temperature WT

Trip Circuit Supervision TCS

Trip Supply Supervision TSS

Overvoltage OV

Undervoltage UV




Protection function Abbreviation

Sensitive Earth Fault SEF




Appendix I Standard current transformer configurations

Figure 3, Figure 4 and Figure 5 are provided to illustrate the standard CT polarity configuration

for protection schemes in the RailCorp HV distribution network.

TRIP DIRECTION

B PHASE

A PHASE

C PHASE

SUBSTATIONBUSBARS

MICOMP127RELAY

45

46

47

48

53

54

55

56

41

42

43

44

49

50

51

52

1 A

CT

5 A

CT

TEST BLOCK

21 23 25 27

22 24 26 28

P1 P2

S1

S1

S1

S2

S2

S2

Figure 3 – CT configuration for directional over-current protection

SUBSTATION BUSBARS

1 A

CT

5 A

CT

B PHASE

A PHASE

C PHASE

MICOMP127RELAY

45

46

47

48

53

54

55

56

41

42

43

44

49

50

51

52

TEST BLOCK

21 23 25 27

22 24 26 28

P1 P2

1 A

CT

5 A

CT

MICOMP124RELAY

45

46

47

48

53

54

55

56

41

42

43

44

49

50

51

52

TEST BLOCK

21 23 25 27

22 24 26 28

P1 P2

TRIP DIRECTION

S2

S2

S2

S2

S2

S2

S1

S1

S1

S1

S1

S1

Figure 4 – CT configuration for rectifier protection




SUBSTATION ABUSBARS

1 A

CT

5 A

CT

B PHASE

A PHASE

C PHASE

MICOMP521RELAY

45

46

47

48

53

54

55

56

41

42

43

44

49

50

51

52

TEST BLOCK

21 23 25 27

22 24 26 28

P1 P2

SUBSTATION BBUSBARS

1 A

CT

5 A

CT

B PHASE

A PHASE

C PHASE

MICOMP521RELAY

45

46

47

48

53

54

55

56

41

42

43

44

49

50

51

52

TEST BLOCK

27 25 23 21

28 26 24 22

P1P2

S2

S2S2

S2

S2 S2

S1

S1

S1

S1

S1

S1

Figure 5 – CT configuration for line differential protection




Appendix J Metering requirements for bulk supply points

The metering requirements in Section J.1 to Section J.6 are applicable to RailCorp substations.

These requirements are correct at the time of publication of this standard and should be

confirmed with the relevant electricity distributor. The specified rated burden should also be

confirmed for suitability, particularly for substations with outdoor yards.

Check metering shall have identical CTs, VTs and energy meter as prescribed in Section J.1 to

Section J.6.

The requirements are based on the following documents:

• Ausgrid Network Standard, ES3 Metering Installation Requirements Part A, Document

NW000-S0141, July 2018

• Endeavour Energy Metering Design Instruction, High Voltage Measurement Current and

Voltage Transformers, Document No: MET 0002 (amendment 0)

• TransGrid, Secondary Systems Design Standard

J.1. Voltage transformers Where the VT is part of an indoor switchboard then a dedicated metering VT is required and

should be located on the associated feeder panel. The VT winding requirements are as follows:

• Indoor switchgear, dedicated winding required (1 per phase), class 0.5 and 50 VA for

Ausgrid, class 0.2 and 100 VA for Endeavour Energy, form factor of 1.9/30 s. Associated

LV ACCB installed on the output with auxiliary contact of ACCB connected to SCADA.

• Outdoor switchgear dedicated winding required (1 per phase), class 0.2 and 50 VA for

Ausgrid, class 0.2 and 100 VA for Endeavour Energy, form factor of 1.9/30 s. Associated

LV ACCB installed on the output with auxiliary contact of ACCB connected to SCADA.

• Warning label required adjacent to VT isolating handle (for example, ‘WARNING - VT

SUPPLIES 7XX REVENUE METERING ’).

J.2. Current transformers A dedicated set of metering class CTs with following parameters shall be provided:

• Ratio: identical to protection CTs on same feeder

• Designation: 15VA CLASS 0.5S

• Designation: 15VA CLASS 0.2 (outdoor CT for Endeavour Energy)




• Thermal limit current = 2.0 A (for 1A secondary CT)

• Rated short-time current and associated time to match the switchboard rating

The CTs are required to be positioned adjacent to the metering CTs used for TfNSW check

metering.

Additional secondary wiring and associated CT links are required for connection to the new

CTs.

J.3. Current transformer and voltage transformer test results The manufacturers’ test reports for the VTs and CTs are required to be submitted to TfNSW and

also stored in the operator and maintainer’s asset management system.

J.4. Secondary wiring from HV switchboard to meter panel The following are the requirements for the installation of the secondary wiring from the CT and

VT:

• The CT and VT secondary wiring is required to be run in separate conduits to the meter

panel.

• The CT secondary wiring shall be a multi-core cable, minimum size of 2.5 mm2.

• The VT secondary wiring shall be a multi-core cable, minimum size of 2.5 mm2 for Ausgrid

and 4 mm2 for Endeavour Energy.

J.5. 240 V ac supply to metering panel A dedicated 240 V ac supply from the substation 415 V distribution board is required to be run

in a dedicated conduit to the metering panel.

The 415 V distribution board is to have appropriate identification label and additional label ‘DO

NOT TURN OFF’ or similar adjacent to the low voltage circuit breaker.

J.6. Metering panel The proposed location of the metering panel has to be approved by the operator and maintainer

prior to installation. The metering panel should be located on the external wall of the substation.

The metering panel shall not be located outside the substation boundary.

The metering panel (including equipment) should be purchased directly from the electricity

distributor or their recommended supplier where available.




Appendix K Wire identification for current transformer, voltage transformer, general protection

Wire identification shall generally be in accordance with AS 2067 Substations and high voltage

installations exceeding 1 kV a.c. The detailed implementation shall be in accordance with Table

7.

Refer to T HR EL 11004 ST Electrical SCADA Interface Requirements and T HR EL 11001 PR

Design Technical Reviews for Electrical SCADA Equipment for details on SCADA cabling and

wiring including communication wiring.

Table 7 – Wire identification

Letter Circuit function Wire numbers

A Current transformers for primary protection, excluding over-current

10-29 Red phase 30-49 White phase 50-69 Blue phase 70-89 Residual circuits and neutral current transformers 90 Earth wires directly connected to the earth bar 91-99 test windings, normally inoperative

B Current transformer for busbar protection


C Current transformers for over-current protection (including combined earth-fault and instruments, H Bridge & double star unbalance)





Letter Circuit function Wire numbers

D Current transformers for instruments, metering voltage control


E Reference voltage of instruments, metering and protection


F Reference voltage for voltage control


K Closing and tripping control circuits Any number from 1 upwards

L Alarms and indications initiated by auxiliary switches and relay contact, excluding those for remote selective control and for general indication equipment

Any number from 1 upwards

T Pilot conductors (including directly associated connections) between panels, independent of the distance between them, for pilot-wire protection, for intertripping or for both


X Alarms and indications to and from general indication and remote selective control equipment. This includes serial communication wiring from protection relays.


Note:

If more numbers are required, add multiples of one hundred. For example, 10-29 may

be extended to 110-129, 210-229.




Appendix L Harmonic filter connection diagram Figure 6 depicts the harmonic filter connection.

Figure 6 - Harmonic filter connection




Appendix M Requirements for copper pilot wire schemes

This appendix provides the requirements for copper pilot wire schemes. The RailCorp HV

distribution network at the time of publication of this standard still has numerous copper based

pilot wire schemes in service.

The following applies:

• A minimum of 15 kV isolation shall be provided to avoid transfer of voltages across the

pilots. This shall be achieved by using an isolation transformer for intertripping by means of

an intertrip relay at both ends of the scheme.

• If the breaker fail function is associated with a feeder that does not have a dedicated

ACCB, then it is acceptable to implement an intertrip by destabilising the pilot wire line

differential schemes of feeders that are a possible source of fault current. When

destabilising the pilot wireline differential schemes this shall be implemented at the pilot

wire line differential relay.

• If the pilot circuit is not run by means of a dedicated pilot cable, then an instantaneous

over-current and earth fault check relay shall be provided in series with the trip from the

pilot wire relay to prevent nuisance tripping of the feeder.

• All pilot wire schemes shall include pilot circuit supervision. This may be implemented

either as a function of the pilot wire relay or using dedicated pilot circuit supervision

equipment.

• Pilot cables shall comply with AS/NZS 2373 Electric cables - Twisted pair for control and

protection circuits.

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