SPI-Programmable - Fundamentals · PDF file3.1 Current Transformers 10 3.2 Power Supply, ......

SPI-Programmable

Overcurrent and Earth Fault Indicators

USER MANUAL

issue 2.1

PRODUCT USER MANUAL doc ref SPi-Programmable issue 2.03

Fundamentals Ltd Page 1

Publication Notice

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All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, including photocopying, electronic, mechanical, recording or otherwise, without the prior written permission of the copyright holder.

Fundamentals Ltd provide this document as is, without warranty of any kind either expressed or implied including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Fundamentals Ltd may make changes or improvements in the software, equipment, or specifications described in this document at any time and without notice. These changes will be incorporated in new releases of this document.

Fundamentals Ltd owns the IPR of the technology contained in this manual. The product was distributed by Nortech Management Ltd for a period of time and equipment illustrations may depict the Nortech logo.

This publication could contain technical inaccuracies or typographical errors. Fundamentals Ltd shall not be liable for any damages (including, but not limited to, consequential, indirect or incidental, special damages or loss of profits or data) even if Fundamentals Ltd have been informed of their potential occurrence, arising out of or in connection with this document or its use.

English Edition All trademark names used in this manual are hereby acknowledged.

Fundamentals Limited Unit 4, Hillmead Enterprise Park Marshall Rd Swindon Wiltshire SN5 5FZ United Kingdom Tel: +44 (0) 1793 847163 Fax: +44 (0) 1793 847245 Web: www.fundamentalsltd.co.uk



Contents

1 General Description 3

2 Operation 5

3 Connections 10

3.1 Current Transformers 10 3.2 Power Supply, Voltage Sensing, Remote Reset &

Alarms 15 3.2.1 Power Supply 15 3.2.2 Mains Sensing 15 3.2.3 Reset 15 3.2.4 Alarms 15

4 Specification 16

5 Environmental Withstand 17

6 Installation 18

7 Operational Checks 20

7.1 Selector Switch Settings 20 7.2 Testing 21 7.2.1 Commissioning Testing 21 7.2.2 Routine Testing 21



1 General Description

The SPi programmable range of fault indicators are designed for application to distribution networks where automated switchgear is installed. When a true fault is detected the indicator operates alarm contacts for remote indication and illuminates an integral Light Emitting Diode (LED). Indicators, strategically placed in the distribution network aid identification of a faulty section of network as shown in fig.1 where a fault occurs at position A.

Fig.1 SPi application to a distribution network

Three designs are available: -

1. An open frame DIN rail mounting unit, figure 2

2. A weather proof unit intended for mounting external to switch-gear, figure 3

3. A weather proof unit intended for mounting external to switch-gear and for use with flexible band CTs only, figure 4

A range of level settings and operating modes are provided as standard, including overcurrent, earth-fault, sensitive earth-fault and persistent current alarms for non-tripping situations. Transient faults can be detected with extended indicating times to allow for a planned inspection of suspect line sections.

The SPi-OCEF programmable is used with three current transformers (CT) mounted within automated switchgear. A separate resistor board is used with the indicator for direct connection to the CTs. Removable connectors on the board allow for connection to the SPi indicator. The separate resistor board is not required for use with flexible band CTs. The power supply to the indicator is taken from local switchgear DC power supply and inputs are provided for local supply voltage sensing.

For a permanent fault the indicating period is selectable for up to 6 hours. For a transient fault the indicating period is 24 hours. In each case contacts are operated for remote alarms.



Inter-board

connectorsAlarms

Fault

NORTECH

MANAGEMENT LTD. UK

www.nortechonline.co.uk

OC

1-2

TIME

5-6

MODE

7-8

0.5A

0.75A

1.0A

1.25A

0.08A

0.12A

0.16A

0.20A

3hr

4hr

5hr

6hr

TRANS

SEF

TRANS

+ SEF

NORMPULSE/

PHASE

EF

3-4

SWITCH SETTINGS

SPi-OCEF

Fault Indicator

VoltageSer. No.

AL/CT

9-10

PULSE/

CORE

HOLD/

PHASE

HOLD/

CORE

SEFPrstnt Crnt

Test/Reset

Ser. No. Ser. No.

Fig.2 SPi-OCEF DIN rail Programmable Indicator

Voltage

SEF

TEST / RESETPress until indicator

stays on

Voltage

VersionSer. No

SPi-OCEFPROGRAMMABLE OVERCURRENT &

EARTH FAULT

INDICATOR

NORTECH MANAGEMENT

LTD, UK


FAULT

Fig.3 SPi-OCEF Potted Programmable Indicator in IP65 enclosure



Voltage

SEF

TEST / RESETPress until indicator

stays on

Voltage

Version


EARTH FAULT

INDICATOR

NORTECH

MANAGEMENT LTD, UK


FAULT

Voltage

FAULTTEST / RESETPress until indicator

stays on

Voltage

VersionSer. No


EARTH FAULT INDICATOR

For use with band CTs only

NORTECH

MANAGEMENT LTD, UK


SEF

Fig.4 SPi-OCEF Potted Programmable Indicator in IP65 enclosure for use with band CTs

2 Operation

Measurement of current is made every 1mSec. When current above the threshold setting of the indicator is measured a fault calculation is initiated. The algorithm used for fault measurement allows the indicator to grade with the minimum settings likely to be used by the source protection relays and at the same time avoid possible mis-measurement due to capacitive charge currents.

The indicator characteristic is shown in App.A against typical source protection minimum settings.

The indicator determines a fault as follows: -

IF the current exceeds the characteristic criteria (app. A)

AND the supply is off within 500mS after the current dropping below the threshold set point

THEN a fault is set



When set for sensitive earth fault (SEF) a fault is defined after 5 seconds of persisting current.

A fault is indicated on the SPi-OCEF by two LEDs. LED1 Indicates for Over Current or Earth Fault and LED2 indicates for SEF. Remote indication is by way of normally open volt free contacts which are closed at the start of the indicating period. Relay contacts can be set as fleeting (2 seconds), or permanently closed until the end of the indicating period or until supply is restored .

When a fault is detected the indicator will not monitor further fault occurrences for 3 minutes following the event to allow for auto-reclose sequence completion. The device will indicate for both transient and permanent faults. When set for permanent fault indications only, the indicator will reset on restoration of supply.

When set for transient fault indications and indicating for fault, the SPi will monitor for new faults and update alarms and indications accordingly, as described below.

For the purpose of explanation the charts below show the operation of the indicator under various fault indicating situations assuming a 3 hour permanent fault time-out period:

On fault detection the indicator will flash to indicate fault passage. If the line voltage is immediately restored the unit will indicate for a total of 24 hours and at the same time monitor the circuit for further faults. If supply is restored immediately, the indicator will sense for new faults after 3 minutes. If supply is restored after the initial 3 minute period following a fault, the indicator will sense for new faults immediately.



If, following a fault, supply is not restored, the unit will indicate for 3 hours. If supply is restored during this period the unit will indicate for 24 hours and monitor and update for further faults.

If, following a fault, supply is not restored within 3 hours, the unit will reset. On restoration of supply the indicator will monitor for new faults.



If, when indicating for a transient fault, fault current is measured, the unit will fully update for the new fault.

If, when indicating for a transient fault, fault current is measured and the line voltage is immediately restored, the unit will indicate for a further 24 hours and fully update for further faults.



If, when indicating for a transient fault supply is lost with no detected fault current, the unit will reset.

If a current above the threshold level is measured and the current continues to flow for 30 seconds, the indicator will flash LED’s alternately and operate relay 2. The indicator will continue to flash until the current ceases.



3 Connections

3.1 Current Transformers

The SPi-OCEF is designed for use with 1A secondary phase mounted current transformers that can be any ratio. If the sensitive earth-fault selection is used, however, the CTs must be matched so that minimal out of balance currents are produced under full load conditions.

Figures 5A and 5B show the arrangement for the phase mounted CTs and the connections from the CT resistor block to the indicator unit. The CTs are terminated at screw terminal connectors for safety. The inter-board wiring is terminated at each end by removable plug connections that facilitate removal of the indicator if required without the need to short out the CT wiring.

Figure 5C shows an alternative arrangement where a core balance CT is used for detection of earth-fault current. In this case a common connection between the CT secondary connections is made to the CT C terminal of the CT resistor block.

Figure 5D shows an arrangement where ‘band CTs are used. In this case the CT resistor block is not required. This type of indicator can only be used in the configuration shown.

Important note:

Phase mounted current transformers must be securely mounted around the cable cores at a point where the core earthed screen passes through and beyond the CT. The jointing procedure for the cable termination should specify the method to be adopted in order to ensure electrical stress control.

The secondary wiring must be earthed, as shown by figure 4A, 4B and 4C.



21 3 4

CT

B

CT

A

CT

C

CO

M

Phase

mounted

CT's

Inter-board

connections

Fault

NORTECH

MANAGEMENT LTD. UK


OC

1-2

TIME

5-6

MODE

7-8

0.5A

0.75A

1.0A

1.25A

0.08A

0.12A

0.16A

0.20A

3hr

4hr

5hr

6hr

TRANS

SEF

TRANS

+ SEF

NORMPULSE/

PHASE

EF

3-4

SWITCH SETTINGS

SPi-OCEF

Fault Indicator

VoltageSer. No.

AL/CT

9-10

PULSE/

CORE

HOLD/

PHASE

HOLD/

CORE

SEFPrstnt Crnt

Test/Reset

Ser. No. Ser. No.

Fig. 5A Current Transformer and Inter-board connections to a DIN rail unit



21 3 4

CT

B

CT

A

CT

C

CO

M

Phase

mounted

CT's

Inter-board

connections

1 2 43

OC

1-2

TIME

5-6

MODE

7-8

200A

300A

400A

500A

30A

50A

70A

90A

3hr

4hr

5hr

6hr

TRANS

SEF

TRANS

+ SEF

NORM PULSE

EF

3-4

SWITCH SETTINGS

ALARM

9-10

PULSE

HOLD

HOLD

Fault

SEF

Prstnt Crnt

Test/Reset

INDICATIONS

Fig. 5B Current Transformer and Inter-board connections to a potted unit



Fig. 5C

Current Transformer connections when using 1 x Core balanced CT + 2 x phase CTs

21 3 4

CT

B

CT

A

CT

C

CO

M

Core

mounted

CT

Phase

mounted

CT's

Fig 3C



Core

mounted

band CT

Phase

mounted

band CT's

1 2 43

OC

1-2

TIME

5-6

MODE

7-8

200A

300A

400A

500A

30A

50A

70A

90A

3hr

4hr

5hr

6hr

TRANS

SEF

TRANS

+ SEF

NORM PULSE

EF

3-4

SWITCH SETTINGS

ALARM

9-10

PULSE

HOLD

HOLD

Fault

SEF

Prstnt Crnt

Test/Reset

INDICATIONS

Fig. 5D Current Transformer connections to a ‘band CT’ unit



3.2 Power Supply, Voltage Sensing, Remote Reset & Alarms

Figure 6 shows the connections to the indicator. Complete isolation is provided between the power supply, the CT input, the mains supply sensing, reset input and the alarm outputs.

BAT

NEG

BAT

POS

MAIN

SENSE

MAIN

SENSE

RESET

POS

RESET

NEG1 2 3 4

ALRM

1

ALRM

1

ALRM

2

ALRM

2

Fig. 6 Connections

3.2.1 Power Supply

The power supply is a nominal 24VDC, the battery earthing may be either positive or negative.

3.2.2 Mains Sensing

An input for local supply sensing is required for fault determination. The voltage applied must be above 40V AC up to 250VAC when the supply is on. After supply is restored, to ensure that supply is fully on, a period of 10 seconds must elapse before the indicator will respond to further fault situations.

3.2.3 Reset

A voltage (9-48VDC) applied to the reset input (polarity sensitive) will reset the indicator.

3.2.4 Alarms

Normally open, isolated contacts are provided for remote signalling of a Fault (Relay 1) and persistent current above the threshold levels but without a loss of supply (Relay 2). The operation of the alarm contacts can be selected to operate as a fleeting alarm (2 seconds duration) or be permanently closed during the indicating period.



4 Specification

Power Supply 1. 14-30V DC (24V nominal)

Quiescent current 30mA

Maximum 100mA, full fault indications

Mains Sensing 40VAC – 250VAC

Reset 1. Local push button, press until both LED’s stay on

2. Remote pulsed reset signal from local telemetry system (9-48VDC) of more than 0.5sec. duration

3. On completion of timing period

Over Current Sensitivity Range

(15%)

0.5A, 0.75A, 1.0A and 1.25A secondary current

(250A, 375A, 500A and 625A primary current using 500/1 CTs)

200A, 300A, 400A and 500A primary current using band CTs

Earth Fault Sensitivity

Range (15%)

Using 3 x Phase CTs

0.08A, 0.12A, 0.16A and 0.2A secondary current

(40A, 60A, 80A and 100A primary current using 500/1 CTs)

Using Core Balanced CT

A single setting of 0.833 A (20%) secondary current

(50A primary current using a 60/1 CT)

Using BAND CT arrangement

30A, 50A, 70A and 90A

Sensitive Earth Fault

Sensitivity (20%)

Using 3 x Phase CTs

5 seconds duration of 0.025A secondary current

Note: while this function is provided, the noise level at this very low current level may give rise to spurious operation

(12.5A primary current using 500/1 CTs)

Using Core Balanced CT (recommended)

A single setting of 0.12A secondary

(7A primary using a 60/1 CT)

Indicator Fault - Red flashing LED1 at 1 second interval

SEF - Red flashing LED2 at 1 second interval

Test - both LED’s flash at 1 second interval, then steady

Persistent Current above threshold without loss of voltage signal - after 30 seconds, LED’s flash alternately until current ceases

Remote Alarm options Two output relays, one for Fault (Alarm 1) and one for persistent current (Alarm 2) with selectable operation as follows: -

1. Fleeting normally open volt free contacts (2.0 Sec)

2. Normally open volt free contacts closed during indicating period

The contact rating is 2A at 30VDC or 0.5A 120VAC



5 Environmental Withstand Insulation

Between any terminal and earth 1.5kV RMS for 1 minute

Between independent circuits 1.5kV RMS for 1 minute

Across normally open contacts 1kV RMS for 1 minute

High Frequency Disturbance

2.5kV Common mode (longitudinal) No mal-operation

1kV Series mode (transverse) No mal-operation

Electrostatic Discharge

8kV contact No mal-operation

Fast Transient

2kV 5/50nSec. 2.5kHz repetitive No mal-operation, steady state, operated or during fault measurement

EMC

Susceptibility 100kHz to 1gHz, 3V/ metre on all planes, no mal-operation

Emissions No significant emissions

Current Injection

Operation Threshold 15% up to at least 20,000A primary current for 3 Sec. through xxx/1 current transformer

Mechanical

General The auxiliary Resistor board and the Indicator are mounted on DIN rail mounting assemblies.

Dimensions Auxiliary Resistor Unit 45Wx78Hx 50D

SPi Indicator (DIN) 112Wx112Hx42D

SPi Indicator (potted) 120Wx120Hx105D

Temperature range -25C to +70C ambient



6 Installation

The SPi-OCEF programmable indicator is used in conjunction with a CT resistor block. The general outline of DIN rail mounted version and the CT resistor block are shown below in fig.7. The weatherproof version is mounted in a case identical to the SPi-OCEF indicator. The relay fascia design is shown in fig.3 (earlier in the document) and the lid rear in fig.8 below.

Current Transformers are connected to the CT resistor block using conductors of sufficient rating for the expected maximum fault current. Care must be taken to ensure that the CTs are mounted with the correct polarity.

109.00

122.0

0

45.0017.00

Fig. 7 Indicator and CT resistor block, general outline



1 2 3 4

120.00

120.0

0

Fig. 8 Potted indicator, general outline



7 Operational Checks

7.1 Selector Switch Settings

The SPi can be programmed for each installation and operational condition by use of a 10 way DIL selector switch. The switch functions are as follows: -

Switch Function

1-2 Overcurrent setting range (CT secondary) nominal 15%

0.5A, 0.75A, 1.0A, 1.25A

200A, 300A, 400A, 500A (band version)

3-4 Earth-fault setting range (CT secondary) nominal 15%

0.08A, 0.12A, 0.16A, 0.2A

30A, 50A, 70A, 90A (band version)

SEF level if set is the same for all EF settings

5-6 Indicating time for permanent fault indications

3hr, 4hr, 5hr, 6hr

7-8 Normal Permanent fault indication only

No Sensitive earth-fault monitor

Transient Transient fault indications

SEF Sensitive earth-fault monitor

Trans/SEF Transient indications AND Sensitive EF

9 Pulsed alarm (2 seconds) or Permanent alarm (closed until supply restored or to end of indicating period)

10 Selection for CT arrangement

1 - 3 phase mounted CTs

2 - 2 phase mounted and 1 core balance CT

Note: This function is not applicable to the band CT version



7.2 Testing

7.2.1 Commissioning Testing

When installed and with the indicator powered up, primary current injection should be carried out to confirm that the CTs are of the correct ratio and polarity. When the current setting of the indicator is reached the appropriate LED will illuminate. As the current is increased above the fault level threshold the LED will switch off as the fault curve time is reached (see app. A).

It is important that CT polarities are correct, the table below shows the minimum tests that should be carried out to confirm correct secondary CT wiring connections. With sensitive earth fault (switch 7) selected, apply a current of 10A through the primary connections of the CTs and confirm the indicator response.

CT A

Source Load

CT B

Source Load

CT C

Source Load

SPi

Indication

Test 1 Inject EF

Test 2 Inject EF

Test 3 Inject EF

Test 4 Injection

Link

None

Test 5 Injection

Link

None

A full operational check of the indicator is achieved as follows: -

1. Apply voltage to the unit and wait for 10 seconds

2. Inject fault current for testing purposes, the LED will indicate when the threshold operating current is reached. When the curve time is reached the LED will switch off.

3. Switch supply AND fault current OFF at the same time

4. Confirm correct indications and alarms

7.2.2 Routine Testing

When powered up the test/reset button located on the lid of the SPi-EF can be used in two ways to confirm the operational readiness, and functionality of the indicator. When testing is being carried out the indicator continues to monitor for fault situations.

1. When operated the LED’s will flash for a short time and then steady until the test/reset button is released, the remote alarm relay contacts will not be operated (Testing Mode 1).



2. If the power supply to the SPi is removed within 15 seconds of test 1, both remote alarm contacts will close and both LED’s will indicate, allowing confirmation of the remote fault indication circuitry. The unit will indicate for 15 seconds and then reset, if supply is restored within 15 seconds the indicator will reset (Testing Mode 2).

If required a full check for operation can be carried out by current injection across the CT secondary terminals of the indicator with simultaneous removal of the mains sensing supply.



App. A

SPi-EF Response against Normal Inverse & Very

Inverse curves using 0.1TM

0.01

0.10

1.00

10.00

1 10 100

PSM

Se

co

nd

s @

0.1

TM

Standard Very SPi-EF

SPI-Programmable - Fundamentals · PDF file3.1 Current Transformers 10 3.2 Power Supply, ......

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