Arcteq AQ-T257 User manual

AQ-T257
Transformer protection IED
Instruction manual
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Table of contents
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1. Manual revision notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1. Version 2 revision notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2. Version 1 revisionnotes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. IED user interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1. Panel structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.1. AQ 250 series local panel structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2. User level password conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5. Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1. Functions included in AQ-T257 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2. Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2.1. Current measurement and scaling in differential application . . . . . . . . . . . . . . . . . .
5.2.2. Voltage measurement and scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2.3. Power and energy calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2.4. Frequency tracking and scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3. General menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4. Protection functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.1. Non-directional overcurrent I> (50/51) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.2. Non-directional earth fault I0> (50N/51N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.3. Directional overcurrent IDir> (67) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.4. Directional earth fault I0Dir> (67N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.5. Current unbalance I2> (46) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.6. Harmonic overcurrent Ih> (50H/51H/68H) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.7. Circuit breaker failure protection CBFP (50BF) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.8. Restricted earth fault / cable end differential (REF) I0D> (87N) . . . . . . . . . . . . . . . .
5.4.9. Overvoltage U> (59) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.10. Undervoltage U< (27) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.11. Neutral voltage U0> (59N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.12. Sequence voltageU1/U2>/<(59P/27P/47) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.13. Over- and underfrequencyf>/< (81O/81U) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.14. Rate-of-change of frequency protection df/dt (81R) . . . . . . . . . . . . . . . . . . . . . .
5.4.15. Power protection (32) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.16. Transformer status monitoring (TRF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.17. Transformer thermal overload protection TT> (49TR) . . . . . . . . . . . . . . . . . . . . .
5.4.18. Transformer differential Idb> Idi> I0dhv> I0dLv> (87T,87N) . . . . . . . . . . . . . . . . .
5.4.19. Voltage memory function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.20. Resistance temperature detectors (Modbus IO) (RTD) (49T) . . . . . . . . . . . . . . .
5.4.21. Arc fault protection IArc>/I0Arc>(50Arc/50NArc) . . . . . . . . . . . . . . . . . . . . . . . .
5.4.22. Programmable stage PGx >/< (99) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5. Control functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.1. Automatic voltage regulator AVR(90) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.2. Setting group selection (SGS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.3. Object control and monitoring (OBJ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.4. Indicator object monitoring (CIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.5. Synchrocheck function ΔV/Δa/Δf (25) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.6. mA Output control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6. Monitoring functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.1. Current transformer supervision (CTS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.2. Fuse failure VTS (60) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.3. Disturbance recorder (DR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.4. Measurement recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.5. Circuit breaker wear-monitor (CBW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.6. Total harmonic distortion monitor (THD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.7. Measurement value recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. System integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AQ-T257
Instruction manual
Version: 2.00
1 © Arcteq Relays Ltd

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6.1. Communication protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.1. NTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.2. ModbusTCP and ModbusRTU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.3. ModbusIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.4. IEC 61850 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.5. GOOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.6. IEC 103 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.7. DNP3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.8. IEC 101/104 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.9. SPA protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2. General IO analog fault registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3. Real time measurements to communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7. Applications and connection examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.1. Connections AQ-T257 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.2. Example 2 winding transformerprotection connection . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3. Trip circuit supervision (95) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8. Construction and installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1. Construction and installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.2. CPU, IO and Power supply module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.3. Current measurement module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.4. Voltage measurement module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.5. Binary input module (DI8) (option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.6. Binary output module (DO5) (option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.7. Arc protection module (option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.8. RTD & mA input module (option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.9. Serial RS232 communication module (option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.10. LC100 Ethernet communication module (option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.11. mAout & mAinput module (option) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.12. Installation dimensioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9. Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1. Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.1. Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.1.1. Power and energy measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.1.2. Current measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.1.3. Voltage measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.1.4. Frequency measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.2. CPU & Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.2.1. Auxiliary voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.2.2. CPU communication ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.2.3. CPU Binary inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.2.4. CPU Binary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.3. Option cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.3.1. Binaryinput module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.3.2. Binary output module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.3.3. Arc protection module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.3.4. mAout & mAin module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.3.5. RTD & mA input module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.1.3.6. RS232 & Serial ber communication module . . . . . . . . . . . . . . . . . . . . . .
9.1.3.7. Double LC100Mb Ethernet module(Redundant) . . . . . . . . . . . . . . . . . . .
9.1.4. Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2. Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1. Protection functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.1. Non-directional overcurrent (50/51) I> . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.2. Non-directional earth fault (50N/51N) I0> . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.3. Directional overcurrent (67) Idir> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.4. Directional earth fault(67N) Iodir> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.5. Current unbalance (46/46R/46L) I2> . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.6. Harmonic overcurrent (50H/51H, 68) Ih> . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.7. Circuit breaker failure protection (50BF/52BF) CBFP . . . . . . . . . . . . . . .
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 2

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9.2.1.8. Restricted earth fault / Cable end differential (87N) Iod> . . . . . . . . . . . . .
9.2.1.9. Overvoltage (59) U> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.10. Undervoltage (27) U< . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.11. Neutral overvoltage (59N) U0> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.12. Sequence voltage(47/27PN/59PN) U1/2>/< . . . . . . . . . . . . . . . . . . . . .
9.2.1.13. Over-/Under frequency(81O/81U) f>/< . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.14. Rate-of-change-frequency(81R) df/dt>/< . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.15. Transformer thermal overload (49T) T> . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.16. Active/Reactive/Apparent power protection (32/37) PQS>/< . . . . . . . . .
9.2.1.17. Resistance temperature detector alarm (49RTD) T> . . . . . . . . . . . . . . .
9.2.1.18. Transformer monitoring function (TRF) . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1.19. Transformer differential (87T,87R) Idb>, Idi>,HV Iod>, LV Iod> . . . . . . .
9.2.1.20. Arc protection (50ARC/50NARC) IARC> I0ARC> (option) . . . . . . . . . . .
9.2.2. Control functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.2.1. Automatic voltage regulator (90) (AVR) . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.2.2. Setting group selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.2.3. Object control (OBJ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.2.4. Synchrocheck (25) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.3. Monitoring functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.3.1. Current transformer supervision (CTS) . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.3.2. Fuse failure VTS (60) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.3.3. Disturbance recorder (DR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.3.4. Circuit breaker wear monitor (CBW) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.3.5. Total harmonic distortion (THD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.3.6. Voltage memory (integrated in 67,21G) . . . . . . . . . . . . . . . . . . . . . . . . . .
9.3. Tests and environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10. Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11. Contact and reference information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AQ-T257
Instruction manual
Version: 2.00
3 © Arcteq Relays Ltd

Disclaimer
Please read these instructions carefully before using the equipment or taking any other actions with
respect to the equipment. Only trained and qualied persons are allowed to perform installation,
operation, service or maintenance of the equipment. Such qualied persons have the responsibility to
take all appropriate measures, including e.g. use of authentication, encryption, anti-virus programs,
safe switching programs etc. necessary to ensure a safe and secure environment and usability of the
equipment. The warranty granted to the equipment remains in force only provided that the instructions
contained in this document have been strictly complied with.
Nothing contained in this document shall increase the liability or extend the warranty obligations of the
manufacturer Arcteq Relays Ltd. The manufacturer expressly disclaims any and all liability for any
damages and/or losses caused due to a failure to comply with the instructions contained herein or
caused by persons who do not full the aforementioned requirements. Furthermore, the manufacturer
shall not be liable for possible errors in this document. 
Please note that you must always comply with applicable local legislation and regulations. The
manufacturer gives no warranties that the content of this document is in all respects in line with local
laws and regulations and assumes no liability for such possible deviations.
You are advised to notify the manufacturer in case you become aware of any errors in this document or
of defects in the equipment.
The manufacturer reserves the right to update or amend this document at any time.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd 4

Copyright
Copyright © Arcteq Relays Ltd. 2018. All rights reserved.
AQ-T257
Instruction manual
Version: 2.00
5 © Arcteq Relays Ltd

1. Manual revision notes
1.1. Version 2 revision notes
Revision 2.00
Date 6.6.2019
Changes
- New more consistent look.
- Improved descriptions generally in many chapters.
- Improved readability of a lot of drawings and images.
- Updated protections included included in every IED manual.
- Every protection IED type now has connection drawing, application example drawingwith function block diagram
and application example with wiring.
- Added current measurement side selection description to functions with such feature.
- Added General-menu description.
1.2. Version 1 revisionnotes
Revision 1.00
Date 13.4.2016
Changes - The rst revision for AQ-T256, T257 and T259 IEDs.
Revision 1.01
Date 10.2.2017
Changes - Order code updated
- Added programmable stage description
Revision 1.02
Date 9.1.2018
Changes
- Measurement value recorder description
- ZCT connection added to current measurement description
- Internal harmonics blocking to I>,I0> function descriptions
- Non-standard delay curves added
- Event lists revised on several functions
- RTD&mA card description improvements
- Ring-lug CT card option description added
- New U> and U< function measurement modes documented
- Order code revised
Revision 1.03
Date 14.8.2018
Changes - Added mA output option card description and ordercode
- Added HMI display technical data
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 6

2. Abbreviations
CB – Circuit breaker
CBFP – Circuit breaker failure protection
CT – Current transformer
CPU – Central processing unit
EMC – Electromagnetic compatibility
HMI – Human machine interface
HW – Hardware
IED – Intelligent electronic device
IO – Input output 
LED – Light emitting diode
LV – Low voltage
MV – Medium voltage
NC – Normally closed
NO – Normally open
RMS – Root mean square
SF – System failure
TMS – Time multiplier setting
TRMS – True root mean square
VAC – Voltage alternating current
VDC – Voltage direct current
SW – Software
uP - Microprocessor
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3. General
AQ-T257Transformer Protection IEDs are a members of the AQ-200 product line. The AQ-200
protection product line in respect of hardware and software is a modular concept. The hardware
modules are assembled and congured according to the application IO requirements and the software
determines the available functions. This manual describes the specic applications of the AQ-T257
Transformer Protection IEDs. For other AQ-200 series products please consult corresponding device
manuals.
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 8

4. IED user interface
4.1. Panel structure
AQ 200 series IED user interface section is divided into hardware- and software user interface
sections. Software interface is divided into local panel conguration and programming by using
AQtivate 200 freeware software suite.
4.1.1. AQ 250 series local panel structure
AQ 200 series IED have multiple LEDs, control buttons, function buttons and local RJ-45 Ethernet port
for conguration on front as a default. On rear each unit is equipped with RS-485 serial interface and
RJ-45 Ethernet interface options as a standard. See list below.
Figure. 4.1.1. - 1. Local panel structure.
4 default LEDs for free conguration: Power, Error, Start and Trip.
16 freely congurable LEDs with programmable legend texts.
3 object control buttons: Choose the controllable object with Ctrl –button, control breaker with
0- and I push buttons.
L/R push button for local remote control.
7 Navigation buttons for IED local programming and a button for password activation.
12 freely congurable function buttons.
RJ-45 Ethernet port for IED conguration.
Used views are freely congurable with buttons for changing settings groups or controlling the relays
logic in general. Object status (Circuit breaker/Disconnector) can be displayed on the screen. All
measured and calculated values (currents, voltages, power, energy, frequency etc.) can be shown in
the screen.
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Instruction manual
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4.2. User level password conguration
As a factory default IEDs do not have any user levels locked behind passwords. In order to activate
different user levels click the IED HMI lock button and set the desired passwords for different user
levels.
NOTE: Passwords can be set only at local HMI.
In the HMI the user level currently in use is indicated in the upper right corner with stars.
Different user levels and the indicators are:
SUPERUSER (***) = full access including congurations
CONFIGURATOR (**) = access to all settings
OPERATOR (*) = access to limited settings and control
USER ( - ) = view only
You can set a new password for the user level by selecting the key icon next to the user level. After this
you can lock the user level by pressing return key while the lock is selected. If you need to change the
password you can select the key icon again and give a new password. Please note that in order to do
this the user level must be unlocked.
The required access level required to change a parameter is indicated with star (*) symbol if such is
required. As a general rule the access levels are divided as follows:
User: Can view any menus and settings but cannot change any settings nor operate breakers
or other equipment.
Operator: Can view any menus and settings but cannot change any settings BUT can operate
breakers or other equipment.
Congurator: Can change most settings like basic protection pick-up levels or time delays,
breaker control functions, signal descriptions etc. Can operate breakers or other equipment.
Super user: Access to change any setting and can operate breakers or other equipment.
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 10

5. Functions
5.1. Functions included in AQ-T257
This chapter presents the functions of AQ-T257Transformer Protection IED. AQ-T257includes
following functions and amounts of instances of the functions.
Table. 5.1. - 1. Protection functions of AQ-T257
Name IEC ANSI Description
NOC1
NOC2
NOC3
NOC4
I>
I>>
I>>>
I>>>>
50/51 Overcurrent protection (4 stages)
NEF1
NEF2
NEF3
NEF4
I0>
I0>>
I0>>>
I0>>>>
50N/51N Residual overcurrent protection (4 stages)
DOC1
DOC2
DOC3
DOC4
Idir>
Idir>>
Idir>>>
Idir>>>>
67 Directional overcurrent protection (4 stages)
DEF1
DEF2
DEF3
DEF4
I0dir>
I0dir>>
I0dir>>>
I0dir>>>>
67N Directional residual overcurrent protection (4 stages)
CUB1
CUB2
CUB3
CUB4
I2>
I2>>
I2>>>
I2>>>>
46/46R/46L Negative sequence overcurrent / phase current reversal / unbalance
protection (4 stages)
HOC1
HOC2
HOC3
HOC4
Ih>
Ih>>
Ih>>>
Ih>>>>
50h/51h/68h
Detection and blocking or tripping from selectable 2nd, 3rd, 4th, 5th, 7th,
9th, 11th, 13th, 15th, 17th, 19th harmonic. Phase currents and residual
currents separate stages. (4 stages)
CBF1 CBFP 50BF/52BF Breaker failure protection
DIF1 Idb>
Idi> 87T Transformer differential function. Biased and non-biased stages
REF1
REF2
I0d>
I0d> 87N Low or high impedance restricted earth fault, cable end differential protection
TOLT1 TT> 49L Transformer thermal overload protection
TRF TRF - Transformer status monitoring function
RTD1 RTD 49T Resistance Temperature Detectors for temperature measurements
OV1
OV2
OV3
OV4
U>
U>>
U>>>
U>>>>
59 Overvoltage protection (4 stages)
UV1
UV2
UV3
UV4
U<
U<<
U<<<
U<<<<
27 Undervoltage protections (4 stages)
VUB1
VUB2
VUB3
VUB4
U1/U2>/<
U1/U2>>/<<
U1/U2>>>/<<<
U1/U2>>>>/<<<<
47/27PN/59PN Sequence voltage protection (4 stages)
NOV1
NOV2
NOV3
NOV4
U0>
U0>>
U0>>>
U0>>>>
59N Neutral voltage protection (4 stages)
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Instruction manual
Version: 2.00
11 © Arcteq Relays Ltd

PQS1 PQS>/< 32 Power protection
FRQV1
f>
f>>
f>>>
f>>>>
f<
f<<
f<<<
f<<<<
81O/81U Frequency protection (8 stages)
ROCOF1 df/dt 81R Rate-of-change of frequency protection (8 stages)
PGS1 PGx >/< 99 Programmable stage
ARC1 IArc>/I0Arc> 50Arc/50NArc Arc protection (Option)
Table. 5.1. - 2. Control functions of AQ-T257
Name IEC ANSI Description
SG - - Set group settings
OBJ - - Object control
SYN ΔV/Δa/Δf 25 Synchrocheck
VRG - - Voltage regulator (Function package)
Table. 5.1. - 3. Monitoring functions of AQ-T257
Name IEC ANSI Description
CTS - - Current transformer supervision
VTS - 60 Fuse failure
DR - - Disturbance recorder
MR - - Measurement recorder
CBW - - Circuit breaker wear monitor
THD - - Total harmonic distortion
VREC - - Measurement value recorder
5.2. Measurements
5.2.1. Current measurement and scaling in differential application
Current measurement module (CT-module) is used for measuring the currents from current
transformers and processing the measured currents to measurement database and for use of
measurement- and protection functions. For the measurements to be correct it is essential to
understand the concept of current measurements.
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 12

Figure. 5.2.1. - 2. Current measurement terminology
PRI: Primary current, the current which flows in the primary circuit and through primary side of the
current transformer.
SEC: Secondary current, the current which the current transformer transforms according to its ratios.
This current is measured by the protection IED.
NOM: Nominal primary current of the protected transformer. Nominal current differs on the HV and LV
side according to the transformer voltage ratio. Nominal current is calculated based on transformers
MVA and nominal voltage on each winding.
For the measurements to be correct it needs to be made sure that the measurement signals are
connected to correct inputs, current direction is connected correctly and the scaling is set correctly.
For scaling, the relay calculates scaling factors based onto the set CT primary, secondary and nominal
current values. Relay measures secondary current which in this case mean the current output from the
current transformer which is installed into the primary circuit of the application. In order the relay to
“know” primary and per unit values it needs to be told the current transformer rated primary and
secondary currents. In case of a power transformer the protected unit nominal current in both windings
is calculated based on given nominal power (MVA) and nominal voltage (V), only when the nominal
current is known the settings can be per unitized to apparatus nominal. By knowing the transformer
nominal current it makes the unit protection a lot easier and straight forward. In modern protection
devices this scaling calculation is done internally after the current transformer primary, secondary and
machine nominal currents are known.
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Instruction manual
Version: 2.00
13 © Arcteq Relays Ltd

Figure. 5.2.1. - 3. Nominal current calculation in differential protection relay
Normally the primary current ratings for phase current transformers are from 10A to thousands of
Amps and their decimal multiples, while normal secondary current ratings are 1 and 5A. Other, non-
standard ratings can be directly connected too since the scaling settings are flexible in large ranges.
For ring core current transformers the ratings may be different. Ring core current transformers are
commonly used for sensitive earth fault protection and their rated secondary may be as low as 0.2 A in
some cases.
In following chapter is given example for the scaling of the relay measurements to the example current
transformers and nominal load.
CT scaling example (application 1)
The connection of CTs to the IED measurement inputs and the ratings of the current transformers and
transformer nominal current are as in following gure.
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 14

Figure. 5.2.1. - 4. Example connection (S1 always to odd connector regardless the CT direction). CT direction is selected under
differential function
Please see the above gure, as a result of the direction of the CTs and according to the fact that P1/S1
side of the CTs are always wired to the odd inputs of the relay CT module, the “Differential calculation
mode” under the Protection → TrafoModule → Idx> [87T,87N] → Settings has to be set as “Subtract”.
Due to this the direction of measured currents are checked correctly from the relay perspective.
Initial data of the connection and the ratings are presented in following table.
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Instruction manual
Version: 2.00
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Table. 5.2.1. - 4. Initial data from example connection.
High voltage side CT:
CT primary 800A
CT secondary 1A
HV-side nominal current:
669A
Ring core CT in Input I02:
3I0CT primary 250A
3I0CT secondary 1A
Low voltage side CT:
CT primary 8000A
CT secondary 1A
LV-side nominal current:
5888A
Both CTs are pointing through the transformer (HV-S2 and LV-S2 are pointing to same direction).
Nominal current for both high voltage and low voltage side of the protected transformer are calculated
based on given values under the “Transformer Characteristics” menu, which is located under the
protection main menu. CT module 1 and 2 ratio can be set directly under the same menu, or optionally
under Measurement → Transformers –menu. Per unit (PU) scaling is automatically set as xed to
“Object In p.u.” in all machine protection relays and it cannot be changed.
Figure. 5.2.1. - 5. Phase current transformer scaling to machine nominal.
As it can be seen in the gure above, the high voltage side nominal current is calculated to be 669.2A
and the low voltage side current is 5888.97A. These nominal currents are calculated as follow:
Per unit values for high –and low voltage side nominal currents can be calculated as shown below:
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 16

To multiply the per unit value with Phase CT secondary side current, it is possible to get the nominal
secondary current of transformer as Amperes. This current can be used when the unit is
commissioned and the directions of CTs are checked. See an example calculation below:
In case coarse residual current (I01) input is used for CT sum (Holmgren) input then it should be set to
phase current CT ratings 100/5A.
Figure. 5.2.1. - 6. Residual current I01 scaling to summing connection.
For the sensitive residual current (I02) measurement the CT primary and secondary currents are set
directly as rated currents 250/1A.
Figure. 5.2.1. - 7. Residual current I02 scaling to ring core CT input.
CT scaling example (application 2)
The connection of CTs to the IED measurement inputs and the ratings of the current transformers and
transformer nominal current are as in following gure.
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Figure. 5.2.1. - 8. Example connection (S1 always to odd connector regardless the CT direction). CT direction is selected under
differential function
Please see the above gure, as a result of the direction of the CTs and according to the fact that P1/S1
side of the CTs are always wired to the odd inputs of the relay CT module, the “Differential calculation
mode” under the Protection → TrafoModule → Idx> [87T,87N] → Settings has to be set as “Add”. The
difference to the rst application is that here the CTs are pointing towards the protected object instead
of pointing through it.
Initial data of the connection and the ratings are presented in following table.
Table. 5.2.1. - 5. Initial data from example connection.
Machine nominal power: 153MVA
Machine high voltage side nominal amplitude: 132kV
Machine low voltage side nominal amplitude: 15kV
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Instruction manual
Version: 2.00
© Arcteq Relays Ltd 18

High voltage side CT:
CT primary 800A
CT secondary 2A
HV-side nominal current:
669A
Ring core CT in Input I02:
3I0CT primary 250A
3I0CT secondary 1A
Low voltage side CT:
CT primary 8000A
CT secondary 5A
LV-side nominal current:
5888A
Both CTs are pointing through the transformer (HV-S2 and LV-S2 are pointing to same direction).
The nominal currents on high voltage and low voltage side are exactly the same as in application 1.
The only difference is that the secondary current level of the CTs have been changed to 2A on high
voltage side and to 5A on low voltage side. Nominal currents are still calculated the same way:
Per unit values for high –and low voltage side nominal currents can be calculated as shown below:
To multiply the per unit value with Phase CT secondary side current, it is possible to get the nominal
secondary current of transformer as Amperes. This current can be used when the unit is
commissioned and the directions of CTs are checked. In application 2 it is necessary to inject higher
amplitudes to the CTs via secondary injection tool to reach the nominal currents. See an example
calculation below:
Settings
Table. 5.2.1. - 6. Settings of the Phase CT scaling
Name Range Step Default Description
Scale
meas to In
0:CT
nom
p.u.
1:Object
In p.u.
-
0:CT
nom
p.u.
Selection of the IED per unit system scaling reference, either the set phase
current CT primary or protected object nominal current. (NOT APPLICABLE IN
MACHINE PROTECTION).
Phase CT
primary
1…
5000.0A 0.1A 100.0A Rated primary current of the CT in amperes.
Phase CT
secondary
0.2…
10.0A 0.1A 5.0A Rated secondary current of the CT in amperes.
AQ-T257
Instruction manual
Version: 2.00
19 © Arcteq Relays Ltd