TRAIN MAINTENANCE BUILDINGS ELECTRICAL SYSTEMS – EARTHING ... · electrical networks standard...

PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION

Engineering Standard- Design

Electrical Networks

MEST 070000-01

TRAIN MAINTENANCE BUILDINGS ELECTRICAL SYSTEMS – EARTHING AND BONDING

Version: 1

Issued: November 2012

Owner: Standards Development Manager

Approved By: Authorise For Use By:

Ahmed Dwidar

Standards Development Manager

Norm Grady

Chief Engineer

ELECTRICAL NETWORKS STANDARD TRAIN MAINTENANCE BUILDINGS ELECTRICAL

SYSTEMS – EARTHING AND BONDING MEST 070000-01

L1-SDD-STD-006 Version: 1 Effective from: 16th November 2012

Approving Manager: Standards Development Manager Approval Date: 16/11/2012 Next Review Date: 16/08/2015 PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION Page 1 of 18

Approval

Amendment Record

Approval Date Version Description

16/11/2012 1 Initial Issue under MTM. Supersedes PTC Electrified Train Maintenance Buildings Standard for Bonding, Isolating and Earthing - 1997





Table of Contents 1 Purpose ........................................................................................................................... 4 2 Scope............................................................................................................................... 4 3 Abbreviation.................................................................................................................... 4 4 Definitions ....................................................................................................................... 4 5 References & Legislations ............................................................................................. 5

5.1 General ........................................................................................................................5 5.2 MTM Standards and Documents ..................................................................................5 5.3 Rail Industry Standards ................................................................................................5 5.4 Australian Standards ....................................................................................................5 5.5 International Standards ................................................................................................5

6 Related Documents ........................................................................................................ 6 7 Safety and Environmental .............................................................................................. 6

7.1 General ........................................................................................................................6 7.2 The Protection of Personnel .........................................................................................6 7.3 The Protection of the Building.......................................................................................6

8 Functionality ................................................................................................................... 7 9 Building Construction and Bonding.............................................................................. 7 10 Building Foundations ..................................................................................................... 8

10.1 General ........................................................................................................................8 10.2 Pad Footings................................................................................................................8 10.3 Driven Piles..................................................................................................................8 10.4 Bored Piles...................................................................................................................8 10.5 Strip Footings...............................................................................................................8

11 Building Ground Floor Slab (without rail tracks).......................................................... 9 12 Building Ground Floor Slab Incorporating Rail Tracks.............................................. 10 13 Building Main Steel Structure ...................................................................................... 10 14 Building Elevated and Suspended Concrete Floor Slabs .......................................... 11 15 Elevated Maintenance Rail Tracks............................................................................... 11 16 Building Walls ............................................................................................................... 12 17 Building Doors .............................................................................................................. 13 18 Traction Overhead Wiring ............................................................................................ 13 19 Rail to Earth Isolation and Traction Current Return................................................... 14 20 Building Services.......................................................................................................... 14 21 Lighting and Power Supply.......................................................................................... 15





22 Signal Power Supply .................................................................................................... 16 23 Communications Power Supply .................................................................................. 16 24 Lightning Protection..................................................................................................... 17 25 Notes.............................................................................................................................. 17 26 Appendices ................................................................................................................... 17





1 Purpose 1.1 To define the requirements for the design and construction of the electrical systems for train

maintenance buildings of the Melbourne metropolitan railway.

2 Scope 2.1 This Standard applies to the design and construction of all new maintenance and cleaning

buildings, including maintenance depots, wash plants, under floor wheel lathe buildings and other buildings designed to accommodate electric trains of the metropolitan railway.

2.2 The Standard applies to building works on the Infrastructure Lease and to works undertaken on other land which are intended to form part of the Infrastructure Lease.

2.3 This Standard specifically addresses the earthing and bonding necessary in a building in which traction power and lighting and power are provided for the maintenance of trains.

2.4 The provisions of this Standard are mandatory.

3 Abbreviation EPZ Equi-potential zone

MTM Metro Trains Melbourne Pty. Ltd.

PVC Polyvinyl Chloride

4 Definitions Bonding Bonding is the act of connecting materials in an area or zone to form

an EPZ.

EPZ An EPZ is an area or zone within which all conductive materials are connected together such that the one electrical potential applies to all materials. The materials are connected by welding or cables termed bonds.

Infrastructure Lease

Is defined as the meaning in the Franchise Agreement.

Shall Is used as the descriptive word to express a requirement that is mandatory to achieve conformance to the standard.

Should Is used as the descriptive word to express a requirement that is recommended in order to achieve compliance to the standard. Should can also be used if a requirement is a design goal but not a mandatory requirement.





5 References & Legislations

5.1 General 5.1.1 The train maintenance building shall be designed and constructed in accordance

with this Standard, relevant MTM standards and Australian, Rail Industry and International Standards.

5.1.2 The design and construction of the facility shall comply with all legislative requirements and codes.

5.1.3 This Standard Supersedes PTC Electrified Train Maintenance Buildings Standard for Bonding, Isolating and Earthing - 1997

5.2 MTM Standards and Documents

Document Number Title

MEST 000002-01 MTM Standard - Traction Substations and Tie Stations

MEST 000002-02 MTM Standard - Overhead Line Electrification

L1-CHE-STD-002 MTM Requirements - Metropolitan Train Maintenance Depot

L0-SQE-PLA-005 Environmental Management Plan

L1-ASY-PRO-001 Engineering Change Procedure

L1-CHE-PRO-001 Standard Waiver Procedure

L1-CHE-PRO-004 Type Approval Procedure

5.3 Rail Industry Standards Nil

5.4 Australian Standards


AS 1554 Structural Steel Welding

AS/NZS 3000 Wiring Rules – 2007 Electrical Installations

5.5 International Standards


BSEN50122-1:2011+A1:2011

Railway applications. Fixed installations. Electrical safety, earthing and the return circuit. Protective provisions against electric shock





BS EN 50122-2:2010 Railway applications. Fixed installations. Electrical safety, earthing and the return circuit. Provisions against the effects of stray currents caused by d.c. traction systems

6 Related Documents MEMF 070000-01 Train Maintenance Building Electrical Systems – Earthing and Bonding

Functional Requirements Template

7 Safety and Environmental

7.1 General 7.1.1 Safety and risk assessments shall be undertaken, addressing all areas of

specification, design, construction, operation and maintenance of the building.

7.1.2 The approach to the design, operation and maintenance of the electrical systems shall be based on the principle of providing a safe and functional environment in so far as is reasonably practical.

7.1.3 Where new materials or systems are to be introduced with the design and construction of the electrical systems, the materials and systems shall be subject to MTM Type Approval and Engineering Change processes for use on the metropolitan train network.

7.1.4 The design, construction and operation of the electrical systems shall comply with the MTM Environmental Management Plan.

7.2 The Protection of Personnel 7.2.1 The building, rail tracks within the building, fixed and portable electrical equipment

shall be designed and constructed to be an EPZ at earth potential.

7.2.2 Personnel shall not be capable of contacting any object at other than EPZ potential within the building or its surroundings.

7.2.3 Failure of any aspect of the traction supply system shall not present a hazard to personnel in the building or surrounds.

7.2.4 Failure of any aspect of the lighting and power supply system shall not present a hazard to personnel in the building or surrounds.

7.3 The Protection of the Building 7.3.1 The building and the rail track within the building shall be isolated from the running

rails of the traction system to prevent the flow of stray current into the structure.

7.3.2 The traction return current of trains within the building shall return to the network through diodes connected across insulated rail joints.

7.3.3 All metal of the building structure and that associated with fixed equipment shall be solidly connected together to form the EPZ and prevent electrolytic corrosion between metallic components.





7.3.4 All connections between metallic parts shall be through conductors rated for the fault currents arising on the traction supply system.

7.3.5 Services to the building provided by metallic piping and similar electrically conductive materials shall be electrically isolated from the building.

8 Functionality 8.1 The electrical systems shall deliver the functionality described following and in accordance

with the details of MEMF 070000-01 Train Maintenance Building Electrical Systems – Earthing and Bonding Functional Requirements Template.

8.2 The electrical systems shall provide for the protection of personnel under normal and abnormal situations.

8.3 The electrical systems shall provide power for the trains and all equipment necessary within the building.

8.4 The electrical systems shall provide for the protection of trains, electrical equipment and the building under normal and abnormal situations.

8.5 The required functionality for the electrical systems shall be achieved by electrical bonding creating an EPZ within the building and electrically isolating the building from the general traction system and lighting and power supply.

9 Building Construction and Bonding 9.1 The requirement is that the building and all metal within the building is an EPZ and near

earth potential. This is achieved through welding, bolting or connecting copper cables between the metallic sections.

9.2 Reinforcement steel within concrete shall be welded as detailed following such that it is electrically continuous.

9.3 Reinforcement steel shall not be painted with epoxy paint or protected prior to welding. Epoxy paint may be used to protect reinforcing rods which are brought out from the concrete to form the electrical connections.

9.4 Metal components such as columns in contact with hold down bolts shall be electrically connected to the hold down bolts and the reinforcing. Hold down bolts shall be welded to the reinforcing and there shall be clean metal to metal contact between the hold down bolts and the other components.

9.5 Where expansion joints exist or there are other construction discontinuities between metallic sections, copper connections shall be provided between the sections. M10 studs shall be welded to the reinforcing or other metal section and a 70 square mm copper conductor, yellow/green PVC insulated connected between the two.

9.6 A minimum of two connections shall be provided between any metal components and the reinforcing of the main building. The connections may be through welding, bolting or connecting cables or a combination of methods.





10 Building Foundations

10.1 General 10.1.1 The design and construction requirements for the reinforcing bars, mesh and cages

and the structure shall be as specified by the structural engineer. The electrical bonding shall be as specified in this Standard.

10.2 Pad Footings 10.2.1 All reinforcing bars in the pad footing shall be welded to form one continuous

electrical unit. The vertical bars shall be a single piece and welded to horizontal bars over the length of the reinforcing. Where reinforcing to the floor or other structures is required, welded connections shall be provided between the pad footing reinforcing and the other reinforcing bars.

10.2.2 The holding-down bolts shall be welded into a cage comprising vertical and horizontal reinforcing bars.

10.2.3 Where a rock anchor is required, the anchor shall be welded to the reinforcing bars. The welding shall be to the end of the rock anchor and not to that section of the rock anchor in tension.

10.3 Driven Piles 10.3.1 The reinforcing in the driven pile shall be welded to form one continuous electrical

unit.

10.3.2 With the pile in position, the reinforcing in the pile shall be welded to reinforcing bars in the pile cap which in turn shall enable welded connections to be made between reinforcing in the floor slab and the holding-down bolts.

10.3.3 A minimum of two welded connections shall be made between the reinforcing in the pile, pile cap, slab floor and holding-down bolts.

10.4 Bored Piles 10.4.1 The reinforcing for the bored piles shall be welded to form one continuous electrical

unit. The bars shall be welded to form an electrically continuous unit at a minimum of two metre intervals.

10.4.2 With the pile in position, the reinforcing in the pile shall be welded to reinforcing bars in the pile cap which in turn shall enable welded connections to be made between reinforcing in the floor slab and the holding-down bolts.

10.4.3 A minimum of two welded connections shall be made between the reinforcing in the pile, pile cap, slab floor and holding-down bolts.

10.5 Strip Footings 10.5.1 The reinforcing in strip footings shall be welded to be electrically continuous with all

bars and mesh connected.





10.5.2 The bars running the length of the strip footing shall be welded for the length of the footing. At distances of not greater than two metres, all longitudinal bars shall be joined with bars welded at right angles.

10.5.3 Where reinforcing mesh is used it shall be welded to the bars at two or more places. The mesh shall be an additional electrical connection to the reinforcing bars to the welded right angled connections.

10.5.4 Where there are reinforcing bars arranged vertically in the strip footing forming two or more layers, the layers shall be connected by welding bars between the layers. The welded vertical connections shall be at two metre maximum centres.

10.5.5 Where the strip footing is adjacent to a ground slab, connections between the strip footing reinforcing and the ground slab reinforcing shall be as for the ground slab.

11 Building Ground Floor Slab (without rail tracks) 11.1 The reinforcing in the floor slab shall form an electrical interconnected grid. The reinforcing

bars running the length of the building shall be welded to form a single continuous conductor. The longitudinal bars shall be crossed at right angles by bars at the ends of the slab and within the slab area at not more than two metre centres with the bars welded at the crossing points.

11.2 Where there are reinforcing bars arranged vertically in the floor slab forming two or more layers, the layers shall be connected by welding bars between the layers. The welded connections shall be at two metre maximum centres both along and across the floor slab.

11.3 Intermediate bars within the reinforcing may be welded or tied to the longitudinal or lateral electrically interconnected bars. Intermediate bars must be welded or tied and not placed on or isolated from the general reinforcing.

11.4 The perimeter reinforcing to the floor slab shall be formed by welded bars. Tied reinforcing bars are not permitted as the perimeter bars.

11.5 The slab floor reinforcing shall be connected by welding to the reinforcing of all foundations.

11.6 Where the reinforcing design calls for a combination of bars and mesh, the bars shall be welded as specified above. The mesh shall be welded to the bars at not less than four points per sheet (standard sheet size 6.0m by 2.4m).

11.7 Where the reinforcing design calls for mesh alone, the sheets shall overlap and be welded together at not less than four points.

11.8 Where the structural design requires expansion joints or other areas where the slab reinforcing is not continuous, M10 studs shall be welded to the reinforcing and a 70 square mm yellow/green PVC insulated copper conductor connected between the two reinforcing grids.

11.9 For expansion joints of 2 metres in length or less a minimum of two separate connections shall be provided across the joints. For expansion joints longer than 2 metres in length, connections shall be provided at a maximum of 2 metre spacing for the length of the joint.

11.10 The floor design and construction shall provide for the studs and cable connections and the protection of the cables. Inspection pit lids shall be rated for the loading of vehicles used within the building and be level with the finished floor level.





11.11 Holding-down bolts and mounting bolts for all metal items including columns, fixtures and fittings attached to or mounted on the floor slab shall be connected to the reinforcing. Holding-down bolts shall provide for clean metal to metal connections between the bolts and the mounted item. Where hold down bolts are not required, M10 studs shall be welded to the reinforcing and a 70 square mm yellow/green PVC insulated copper conductor provided to make the connection.

11.12 Where the building design and construction calls for concrete slab walls or sheet metal walls, connections between the reinforcing and metal of the walls and the reinforcing of the floor slab shall be provided.

12 Building Ground Floor Slab Incorporating Rail Tracks 12.1 The design and construction of the reinforcing for the building floor slab incorporating rail

tracks shall conform to the above requirements for the building floor slab with the following additional requirements.

12.2 The floor slab shall be designed and constructed to incorporate the rails, connection and inspection pits and conduits for cables. All cables within the floor slab shall be in conduit. Inspection pit lids shall be rated for the loading of vehicles used within the building and be level with the finished floor level.

12.3 At 10 metre intervals, each rail shall be connected to the floor slab reinforcing. The connecting cable shall be a 70 square mm yellow/green PVC insulated copper conductor bolted to the web of the rail which is cad welded to the longitudinal reinforcement bars.

12.4 The two rails of each track shall be bonded together within five metres of both ends of the floor slab with insulated copper conductor of 150 square mm.

12.5 From each track, two 150 sq mm cables shall be run in conduit and be connected to the base of a main steel column supporting the building roof. The two cables for the one track shall be installed in a single conduit. The cables from all the tracks in the building shall be connected to the one main steel column. The connections to the column shall be subject to ready visual examination and be protected from damage.

12.6 Two 150 sq mm cables shall be attached to the main steel column adjacent to the cable connections from the tracks and run in conduit as parallel conductors to a cabinet installed against the internal wall of the building which houses the blocking diode unit. The cables shall be connected to the anode of the blocking diodes.

12.7 A conduit shall be provided from the cabinet housing the blocking diode unit to the front of the building and through the independent concrete slab to carry four 150 sq mm cables.

13 Building Main Steel Structure 13.1 The main steel structure shall be electrically continuous with the reinforcing in the floor slab

connected through the holding-down bolts and 70 square mm yellow/green PVC insulated copper conductor. Every column base shall have a clean metal to metal connection to the holding-down bolts. Secondary steel structural components and sheet metal wall cladding shall be electrically continuous with the main steel structure.





13.2 The secondary steel structural members shall be bolted clean metal to metal with the matching surfaces free from paint and other materials. Sheet metal cladding shall be fixed to the structural members by bolts or rivets. Clean metal to metal connection is not required between the sheet metal cladding and the supporting structural steel.

13.3 Steel members supporting the overhead traction wiring fittings, including overhead switches, shall be directly connected to the main columns and roof beams of the building. Special attention shall be given to the design and construction to ensure that there are clean metal to metal connections between all steel work between the overhead wiring supports and the columns connected to the cables from the rail tracks.

14 Building Elevated and Suspended Concrete Floor Slabs 14.1 The design and construction of the reinforcing for the building elevated and suspended floor

slabs shall conform to the above requirements for ground floor slabs without rail tracks with the following additional requirements.

14.2 The reinforcing in elevated and suspended concrete floor slabs shall be electrically connected to the reinforcing in the ground floor slab.

14.3 Where the elevated or suspended concrete floor slab is supported on steel structure, joins in the supporting steel work shall be clean metal to metal to ensure the electrical connectivity of the steel.

14.4 The reinforcing of the elevated or suspended concrete floor slab shall be welded as described for ground floor slabs. Additionally, certain reinforcing bars shall be welded to the horizontal supporting steel members where the bars cross the steel supports. The bars at the perimeter of the elevated or suspended floor slab shall be welded to the steel supporting members with intermediate bars welded at two metre centres.

14.5 Where the elevated or suspended concrete floor slab is formed on steel decking which is integral to the final structure, the steel decking shall be welded to each supporting steel member. Reinforcing bars within the elevated or suspended concrete floor slab shall be welded to the steel supports as described above.

14.6 Where the elevated or suspended concrete floor slab is supported on concrete walls such as prefabricated or tilt-up slabs, the reinforcing bars within the elevated or suspended concrete floor slab shall be connected to the reinforcing bars within the walls by welding, purpose built bolted connections or M10 studs welded to the reinforcing with a 70 square mm yellow/green PVC insulated copper cable.

14.7 Prefabricated elevated or suspended concrete floor slabs shall be constructed with the reinforcing in accordance with this Standard.

15 Elevated Maintenance Rail Tracks 15.1 The reinforcing to the floor of the building below the elevated maintenance rail tracks shall

conform to the building ground floor slab requirements above.

15.2 The rails of the elevated maintenance rail tracks shall be electrically connected to the reinforcing in the ground floor slab.

15.3 Where the support for the elevated rail track is on metal columns, the columns shall be mounted on holding-down bolts which are welded to the reinforcing. The metal columns shall have a clean metal to metal connection to the steel supporting the rail.





15.4 The rail shall be connected to the supporting steel at 10 metre centres by welding the rail flange to the steel. Alternatively, a 70 square mm yellow/green PVC insulated copper conductor may be provided to make the connection.

15.5 The two rails of each track shall be bonded together within five metres of both ends of the floor slab (or the end of the rails) with insulated copper conductor of 150 square mm.

15.6 Where the support for the elevated rail track is on concrete columns, the reinforcing in the columns shall be fully welded and also welded to the longitudinal bars within the ground slab. At not more than 10 metre intervals, a 70 square mm yellow/green PVC insulated copper cable shall be cad welded to the reinforcing in the column and connected to both the supporting steel and the rail.

16 Building Walls 16.1 Building walls are variously concrete slab, concrete block, brick work or sheet metal.

16.2 The reinforcing of concrete slab walls shall be welded to form an interconnected electrical grid within each unit. The vertical and horizontal bars within the unit shall be welded such that each bar is electrically continuous for its length. At the perimeter of the unit, the vertical and horizontal bars shall be welded together. Within the area of the slab, the vertical and horizontal bars shall be welded where they cross in a grid at two metre centres.

16.3 Where the design of the reinforcing for the slab wall requires mesh, the mesh shall be welded to the reinforcing bars at not less than four points per sheet.

16.4 The reinforcing within the slab walls shall be connected to the reinforcing of the floor slab. Permitted connections are by welding together reinforcing bars between the walls and floor reinforcement and using 70 square mm yellow/green PVC insulated copper conductor attached to M10 studs welded to the reinforcing.

16.5 For welding of the reinforcing between the wall slab and the floor slab, N20 bars shall be projected from the wall slab reinforcing, floor slab reinforcing or both and welded in position. The copper conductor connection requires the M10 studs to be welded to the reinforcing and the cable put in place. The design and construction shall ensure that the welded or cable connections are secure and protected from damage.

16.6 Connections between the wall slab reinforcing and the floor slab reinforcing shall be a minimum of two connections per wall slab unit or a connection every two metres of wall slab length, which ever is the greater.

16.7 Concrete block or brick work walls require no electrical connections.

16.8 Sheet metal walls shall be electrically continuous and connected to the reinforcing of the floor slab. The usual means of connection is through the wall studs and horizontal beams attached to the steel building columns which in turn are attached to the reinforcing through the holding-down bolts.

16.9 Where the design of the building provides for a sheet metal wall not to be connected to the floor slab reinforcing through the metal structure as above, the sheeting shall be connected together through a metal section and then using 70 square mm yellow/green PVC insulated copper conductor, suitably located and protected against damage, connected to the floor slab reinforcing.





17 Building Doors 17.1 The doors providing for train entry to the building are generally of steel structure. Where the

doors are steel or of electrical conductive material, each door shall be connected to the building structure by a flexible copper conductor of 70 square mm in cross section.

17.2 Access doors for personnel may be metal or timber. Bonding of the doors to the building structure is not required.

17.3 Fixings and Equipment

17.4 Fixed railings and platforms constructed of metal within the building shall be connected to the reinforcing of the ground slab directly or through reinforcing, steel structure or cable. At least two connections shall be made between each fixed railing and platform and the reinforcing. For platforms and railings over 10 metres in length, a connection shall be made every 10 metres.

17.5 Overhead cranes shall have the supporting steel connected to the reinforcing of the ground slab directly or through steel structure or cable. At least two connections shall be made between the crane supporting beam and the reinforcing. For crane supporting beams over 10 metres in length, a connection shall be made every 10 metres.

17.6 In floor train hoists shall be connected to the reinforcing of the ground floor slab incorporating rail tracks using 70 square mm yellow/green PVC insulated copper conductor. At least two independent connections shall be made to each separate component of the bogie hoists.

17.7 Where the form of train hoist is a bogie hoist that raises or lowers a section of rail, two copper cables each of 150 square mm in cross section shall be connected around the break in each rail to provide continuity for the traction current.

18 Traction Overhead Wiring 18.1 The traction overhead wiring shall be arranged to provide for traction power to each track

such that the power to each track may be isolated and connected to rail independently.

18.2 The overhead switches for each track shall be inside the building, placed adjacent to the track and labelled such that it is clear and unambiguous which overhead switch controls the traction supply to which track.

18.3 The overhead switch shall have a “live” position connecting the overhead wiring within the building to the 1500V traction supply system. It shall also have an “earthed” position, connecting the overhead wiring to rail and the steel structure of the building.

18.4 The rail or earthed position of the switch shall be connected to two paralleled 70 square mm blue PVC insulated copper cables which shall be connected to the steel column of the main building structure to which the 150 square mm cables from the tracks are connected. The cables from the overhead switches shall be attached to the steel column adjacent to the cables from the tracks.

18.5 The cables shall be labelled at the connection points to the steel column as “Overhead Switch to Rail Conductors – Do not Remove”. The connections to the column shall be subject to ready visual examination and be protected from damage.

18.6 The two 70 square mm blue PVC insulated copper cables may be used as a common conductor for the rail or earth position connections for all the overhead switches in the building.





19 Rail to Earth Isolation and Traction Current Return 19.1 The foundations, floor slab and all of the building structure shall be independent of all other

structures. In particular, there shall be no metal connections between the building and any external structure, piping or incoming building services.

19.2 At the train entrance doors of the building, an independent concrete slab shall be formed to carry the rail tracks and permit road vehicle access to the building for maintenance purposes. Ideally the slab shall be formed without steel reinforcing or with non metallic reinforcing. If the ground conditions and slab loading require steel reinforcing, the reinforcing is not to be in contact with any part of the building or the rails. A minimum distance of 75 mm shall be maintained between steel reinforcing and the rails within the formed concrete.

19.3 The rails in the independent concrete slab shall be insulated from the concrete with the rail surfaces in the concrete painted with long life two-part epoxy paint. The entire surface of the embedded rail shall be coated without any breaks in the paint coating. Any surface areas damaged during placement of the rails shall be made good prior to placing of the concrete.

19.4 At a distance between 3 metres to 5 metres from the front of the building floor slab, insulated rail joints shall be installed in each rail within the independent concrete slab. The insulated rail joints prevent rail to earth potentials associated with the operation of trains on the network being applied to the building. The epoxy paint shall be applied over the insulated rail joints.

19.5 A blocking diode unit shall be installed in the building which permits traction return current to flow from the building to the rail network but which protects the building structure from stray current damage. The diode(s) shall be full time rated at 3,500 amps with a short circuit current rating of 25kA for 10 mSec.

19.6 The traction return current from the building is provided for by four 150 sq mm cables connected in parallel from the cathode of the blocking diode unit to power rails on the network side of the insulated rail joints. The cables shall be connected to two power rails of the network, two to each power rail. The cables shall be run in conduit and terminated at the rails from cable pits. The cables and the cable pit covers shall be labelled “Building Traction Return Cables”.

19.7 To guard against an open circuit failure of the blocking diode unit, an over voltage detection relay shall be fitted in parallel with the diodes to detect an open circuit and short circuit the diodes.

19.8 On the detection of a voltage across the diodes in excess of 60 volts the over voltage detection relay shall operate and simultaneously trip the direct current circuit breaker supplying the traction power to the building.

19.9 The over voltage detection relay shall be full time rated at 750 amps. Operation of the relay shall be monitored continuously and indicated in the Electrol system.

20 Building Services 20.1 Services provided in metallic piping and similar conducting materials entering the building

shall be above ground and protected from interference and damage. The protection shall ensure that persons do not come into simultaneous contact with the in ground services piping and the building or the services entries into the building.





20.2 For the protection of persons and the building structure, services in metallic pipes within the building shall be connected to the structure forming the EPZ.

20.3 To protect the service assets from stray current corrosion, services provided in metallic pipes shall have an insulating section comprising an insulating flange or a section of minimum length of 150 mm inserted in the pipe. The insulating section shall be above ground level and external to the building.

20.4 At the point of entry inside the building, the metal pipes shall be connected to the building structure with a green/yellow cable of a minimum of 16 sq mm in cross section.

20.5 Only the electric supply from the building specific lighting and power supply shall be provided to the building.

20.6 Water mains, including general use and fire services shall be fitted with insulating sections.

20.7 Sewerage services shall be constructed in plastic piping.

20.8 Gas supplies shall be provided in plastic piping.

20.9 Pneumatic air supply shall be provided by a compressor installed within the building and powered by the lighting and power supply for the building.

20.10 Metallic service pipes shall not be installed in concrete floor slabs or walls. This restriction applies to both bare and insulated service piping.

21 Lighting and Power Supply 21.1 An independent lighting and power supply shall be provided for the building. The design

and construction of the supply shall ensure that the system is safe for users and is not affected by stray or fault currents arising from the traction supply system.

21.2 The maintenance building shall be supplied from a transformer (or transformers) which are physically and electrically remote from the building. The transformer(s) shall be a minimum of 10 metres from the building.

21.3 If the transformers are fenced, the fence enclosing the transformer(s) shall be a minimum of 10 metres from the building.

21.4 The transformer cases and the fence if it is constructed of metal shall be earthed to a local earth grid adjacent to the transformers. The earth grid shall not be within 10 metres of the building or the building foundations.

21.5 The incoming supply to the transformer(s) shall not be earthed to the adjacent earth grid but to a remote earth grid at the source of the supply.

21.6 The secondary output of the transformer(s) supplying the building shall be cabled into the building as a four wire supply to the main switchboard. The neutral connection(s) shall be isolated from the transformer case(s) and adjacent earth grid. The neutral cables shall be terminated on to a neutral conductor within the main switch board.

21.7 The neutral conductor shall be connected to an earth bar within the main switch board. The connection between the conductor and bar shall be by two independent links or cables each of which has the same current carrying capacity as the neutral conductor.





21.8 To bring the neutral of the lighting and power supply to the potential of the EPZ, the earth bar shall be connected to the building steel structure at the column to which the 150 square mm cables from the tracks and the two 70 square mm blue PVC insulated copper cables from the overhead switches are connected. The connecting cables shall be four 70 square mm yellow/green PVC insulated copper conductors. Four cables shall be run in parallel from the earth bar to the column. The connections to the column shall be subject to ready visual examination and be protected from damage.

21.9 The cables at the column shall be labelled “Lighting and Power Earth – Do not remove”.

21.10 The earthing of the neutral conductor at the main switch board through its connections to the earth bar and the building structure and reinforcement forms the main earth for the building. Insulated earthing conductors shall be run with the sub-mains cables from the main switch board to each distribution board and with the final sub-circuit cables from each distribution board.

21.11 The lighting and power supply shall only be earthed at the main switch board. In the event of a traction power supply fault, fault currents may flow in a secondary earth in excess of its rating causing failure and leaving the circuit not protected by an earth.

21.12 The electrical installation for the building shall be in conformance with Section 7 of AS 3000 as required for the Isolated Supply.

21.13 Where cables are required to be installed in conduits, the cables shall be double insulated.

21.14 The lighting and power supply for the building shall supply the building only and no other electrical installation. The supply may be used for external lighting of the building surrounds but only for light fittings mounted on the building. External power points are not permitted.

22 Signal Power Supply 22.1 Where a signal box, signal relay room or computer room is required in the maintenance

building, the following shall apply for the signalling electrical systems.

22.2 50V DC and 110V AC circuits shall be isolated from the building. Cables through the floor and wall structures shall be in PVC conduit and rated 0.6/1kV. Conduits shall be continuous and sealed against moisture.

23 Communications Power Supply 23.1 Power supply to the communications equipment shall be an essential supply. Where the

reliability of the lighting and power supply to the building is considered appropriate, the communications equipment may be supplied from that source.

23.2 The communications equipment supplied from the building lighting and power supply shall not power equipment remote to the building at 230 volts or above. Remote communications equipment may be supplied from the building lighting and power supply if it is a low or extra low voltage supply fully isolated from the building.

23.3 Should it be determined that a different power source is required for the communications or other essential equipment, the principles applicable to the lighting and power supply for the building shall apply. The supply shall be through an isolating transformer, the neutral conductor and earth bar connected and the earth bar bonded to the structure (and reinforcing) of the building being the EPZ.





23.4 The earthing cables shall be two 70 square mm yellow/green PVC insulated copper conductors connected between the earth bar and the column to which the other rail connections and lighting and power earths are connected.

23.5 The cables at the column shall be labelled “Lighting and Power Secondary Supply Earth – Do not remove”.

24 Lightning Protection 24.1 The building shall be provided with lightning protection. The lightning conductors shall be

supported by but insulated from the building. The insulators shall be designed for external use and rated at 3kV.

24.2 The lightning system earth electrodes shall be installed one metre from the building foundation. The lower section of the lightning conductor shall be in conduit and protected against inadvertent contact with the building and its foundations.

25 Notes Nil

26 Appendices Appendix 1 – Responsibilities





Appendix 1 - Responsibilities

The persons nominated in the following table shall be responsible for the specification, design and construction of the Metropolitan Train Maintenance building.

Responsible Person Functional Area/Activity

Responsibilities Comments

Overall approval of the Train Maintenance Building

Approval of assets Input to the design process

Network Asset Manager

Design Approval Approval of assets

Project Manager Design and Construction Works

Delivery of the train maintenance building to scope, schedule, quality and cost

Manager Network Planning and Development

Overall Approval Approval of the train maintenance building project as a whole through development to operation

To sign the project scope prior to commitment to construction

Manager Infrastructure Delivery

Acceptance of project Acceptance of the assets for operation

TRAIN MAINTENANCE BUILDINGS ELECTRICAL SYSTEMS – EARTHING ... · electrical networks standard...

Documents

Transcript of TRAIN MAINTENANCE BUILDINGS ELECTRICAL SYSTEMS – EARTHING ... · electrical networks standard...