ABB RELION RET670 Instructions for use

RELION® 670 SERIES
—
Transformer protection RET670
Version 2.2 ANSI
Application manual

Document ID: 1MRK 504 163-UUS
Issued: October 2017
Revision: A
Product version: 2.2.1
© Copyright 2017 ABB. All rights reserved

Copyright
This document and parts thereof must not be reproduced or copied without written
permission from ABB, and the contents thereof must not be imparted to a third party,
nor used for any unauthorized purpose.
The software and hardware described in this document is furnished under a license and
may be used or disclosed only in accordance with the terms of such license.
This product includes software developed by the OpenSSL Project for use in the
OpenSSL Toolkit. (http://www.openssl.org/) This product includes cryptographic
software written/developed by: Eric Young ([email protected]) and Tim Hudson
([email protected]).
Trademarks
ABB and Relion are registered trademarks of the ABB Group. All other brand or
product names mentioned in this document may be trademarks or registered
trademarks of their respective holders.
Warranty
Please inquire about the terms of warranty from your nearest ABB representative.

Disclaimer
The data, examples and diagrams in this manual are included solely for the concept or
product description and are not to be deemed as a statement of guaranteed properties.
All persons responsible for applying the equipment addressed in this manual must
satisfy themselves that each intended application is suitable and acceptable, including
that any applicable safety or other operational requirements are complied with. In
particular, any risks in applications where a system failure and/or product failure would
create a risk for harm to property or persons (including but not limited to personal
injuries or death) shall be the sole responsibility of the person or entity applying the
equipment, and those so responsible are hereby requested to ensure that all measures
are taken to exclude or mitigate such risks.
This document has been carefully checked by ABB but deviations cannot be
completely ruled out. In case any errors are detected, the reader is kindly requested to
notify the manufacturer. Other than under explicit contractual commitments, in no
event shall ABB be responsible or liable for any loss or damage resulting from the use
of this manual or the application of the equipment.

Conformity
This product complies with the directive of the Council of the European Communities
on the approximation of the laws of the Member States relating to electromagnetic
compatibility (EMC Directive 2004/108/EC) and concerning electrical equipment for
use within specified voltage limits (Low-voltage directive 2006/95/EC). This
conformity is the result of tests conducted by ABB in accordance with the product
standard EN 60255-26 for the EMC directive, and with the product standards EN
60255-1 and EN 60255-27 for the low voltage directive. The product is designed in
accordance with the international standards of the IEC 60255 series and ANSI C37.90.

Table of contents
Section 1 Introduction..........................................................................27
This manual............................................................................................ 27
Intended audience.................................................................................. 27
Product documentation...........................................................................28
Product documentation set................................................................28
Document revision history................................................................. 29
Related documents............................................................................30
Document symbols and conventions...................................................... 30
Symbols.............................................................................................30
Document conventions...................................................................... 31
IEC 61850 edition 1 / edition 2 mapping.................................................32
Section 2 Application...........................................................................43
General IED application..........................................................................43
Main protection functions........................................................................45
Back-up protection functions.................................................................. 46
Control and monitoring functions............................................................ 48
Communication.......................................................................................53
Basic IED functions.................................................................................56
Section 3 Configuration....................................................................... 59
Description of configuration RET670...................................................... 59
Introduction........................................................................................59
Description of configuration A10...................................................59
Description of configuration A25...................................................62
Description of configuration B30...................................................63
Description of configuration B40...................................................66
Section 4 Analog inputs.......................................................................69
Introduction.............................................................................................69
Setting guidelines................................................................................... 69
Setting of the phase reference channel.............................................69
Example........................................................................................70
Setting of current channels................................................................70
Example 1.....................................................................................71
Example 2.....................................................................................71
Example 3.....................................................................................72
Table of contents
Transformer protection RET670 2.2 ANSI 1
Application manual

Examples on how to connect, configure and set CT inputs
for most commonly used CT connections.................................... 75
Example on how to connect a wye connected three-phase
CT set to the IED.......................................................................... 76
Example how to connect delta connected three-phase CT
set to the IED................................................................................81
Example how to connect single-phase CT to the IED.................. 84
Relationships between setting parameter Base Current, CT
rated primary current and minimum pickup of a protection IED........ 86
Setting of voltage channels............................................................... 86
Example........................................................................................87
Examples how to connect, configure and set VT inputs for
most commonly used VT connections..........................................87
Examples on how to connect a three phase-to-ground
connected VT to the IED.............................................................. 88
Example on how to connect a phase-to-phase connected
VT to the IED................................................................................ 90
Example on how to connect an open delta VT to the IED for
high impedance grounded or ungrounded networks.................... 92
Example how to connect the open delta VT to the IED for
low impedance grounded or solidly grounded power systems..... 95
Section 5 Local HMI............................................................................ 99
Display.................................................................................................. 100
LEDs.....................................................................................................103
Keypad..................................................................................................104
Local HMI functionality..........................................................................106
Protection and alarm indication....................................................... 106
Parameter management .................................................................107
Front communication....................................................................... 108
Section 6 Wide area measurement system.......................................109
C37.118 Phasor Measurement Data Streaming Protocol
Configuration PMUCONF..................................................................... 109
Identification.................................................................................... 109
Application....................................................................................... 109
Operation principle.......................................................................... 109
Short guidance for use of TCP................................................... 110
Short guidance for use of UDP...................................................111
Protocol reporting via IEEE 1344 and C37.118 PMUREPORT............ 113
Identification.................................................................................... 113
Application....................................................................................... 114
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2Transformer protection RET670 2.2 ANSI
Application manual

Operation principle.......................................................................... 116
Frequency reporting................................................................... 118
Reporting filters.......................................................................... 120
Scaling Factors for ANALOGREPORT channels....................... 121
PMU Report Function Blocks Connection Rules in PCM600
Application Configuration Tool (ACT)......................................... 123
Setting guidelines............................................................................ 129
Section 7 Differential protection........................................................ 135
Transformer differential protection T2WPDIF and T3WPDIF (87T)......135
Identification.................................................................................... 135
Application....................................................................................... 135
Setting guidelines............................................................................ 136
Restrained and unrestrained differential protection....................136
Elimination of zero sequence currents....................................... 140
Inrush restraint methods.............................................................140
Overexcitation restraint method..................................................140
Cross-blocking between phases.................................................141
External/Internal fault discriminator............................................ 141
On-line compensation for on-load tap-changer position.............143
Differential current alarm............................................................ 144
Open CT detection..................................................................... 144
Switch onto fault feature............................................................. 145
Setting example...............................................................................145
Introduction.................................................................................145
Typical main CT connections for transformer differential
protection....................................................................................146
Application Examples................................................................. 147
Summary and conclusions......................................................... 155
High impedance differential protection, single phase HZPDIF (87)......157
Identification.................................................................................... 157
Application....................................................................................... 158
The basics of the high impedance principle............................... 158
Connection examples for high impedance differential protection.... 164
Connections for three-phase high impedance differential
protection....................................................................................164
Connections for 1Ph High impedance differential protection
HZPDIF (87)............................................................................... 165
Setting guidelines............................................................................ 166
Configuration.............................................................................. 167
Settings of protection function.................................................... 167
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Transformer protection RET670 2.2 ANSI 3
Application manual

T-feeder protection..................................................................... 167
Tertiary reactor protection.......................................................... 170
Restricted earth fault protection (87N)........................................173
Alarm level operation..................................................................175
Low impedance restricted earth fault protection REFPDIF (87N).........176
Identification.................................................................................... 176
Application....................................................................................... 176
Transformer winding, solidly grounded.......................................177
Transformer winding, grounded through Zig-Zag grounding
transformer................................................................................. 178
Autotransformer winding, solidly grounded................................ 179
Reactor winding, solidly grounded..............................................180
Multi-breaker applications...........................................................181
CT grounding direction............................................................... 182
Setting guidelines............................................................................ 182
Setting and configuration............................................................182
Settings.......................................................................................183
Additional security logic for differential protection LDRGFC (11)......... 184
Identification.................................................................................... 184
Application....................................................................................... 184
Setting guidelines............................................................................ 186
Section 8 Impedance protection........................................................189
Distance measuring zone, quadrilateral characteristic for series
compensated lines ZMCPDIS (21), ZMCAPDIS (21), ZDSRDIR
(21D).....................................................................................................189
Identification.................................................................................... 189
Application....................................................................................... 189
Introduction.................................................................................189
System grounding.......................................................................190
Fault infeed from remote end..................................................... 192
Load encroachment....................................................................193
Long transmission line application..............................................194
Parallel line application with mutual coupling............................. 195
Tapped line application...............................................................203
Series compensation in power systems..................................... 205
Challenges in protection of series compensated and
adjacent power lines...................................................................214
Impact of series compensation on protective IED of
adjacent lines..............................................................................226
Distance protection.....................................................................227
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4Transformer protection RET670 2.2 ANSI
Application manual

Setting guidelines............................................................................ 235
General.......................................................................................235
Setting of zone1..........................................................................236
Setting of overreaching zone......................................................236
Setting of reverse zone...............................................................237
Series compensated and adjacent lines.....................................237
Setting of zones for parallel line application............................... 243
Setting of reach in resistive direction..........................................245
Load impedance limitation, without load encroachment
function.......................................................................................245
Load impedance limitation, with load encroachment function
activated..................................................................................... 247
Setting of minimum operating currents.......................................247
Setting of timers for distance protection zones...........................248
Phase selection, quad, fixed angle, load encroachment
FDPSPDIS (21).................................................................................... 248
Identification.................................................................................... 248
Identification............................................................................... 248
Application....................................................................................... 249
Setting guidelines............................................................................ 249
Load encroachment characteristics............................................249
Resistive reach with load encroachment characteristic..............255
Minimum operate currents..........................................................256
Distance measuring zones, quadrilateral characteristic ZMQPDIS
(21), ZMQAPDIS (21), ZDRDIR (21D)..................................................257
Identification.................................................................................... 257
Application....................................................................................... 257
System grounding.......................................................................257
Fault infeed from remote end..................................................... 261
Load encroachment....................................................................262
Short line application.................................................................. 263
Long transmission line application..............................................264
Parallel line application with mutual coupling............................. 265
Tapped line application...............................................................272
Setting guidelines............................................................................ 275
General.......................................................................................275
Setting of zone 1.........................................................................276
Setting of overreaching zone......................................................276
Setting of reverse zone...............................................................277
Setting of zones for parallel line application............................... 278
Table of contents
Transformer protection RET670 2.2 ANSI 5
Application manual

Setting of reach in resistive direction..........................................279
Load impedance limitation, without load encroachment
function.......................................................................................280
Load impedance limitation, with Phase selection with load
encroachment, quadrilateral characteristic function activated ...282
Setting of minimum operating currents.......................................282
Directional impedance element for quadrilateral characteristics 282
Setting of timers for distance protection zones...........................285
Full-scheme distance measuring, Mho characteristic ZMHPDIS (21).. 285
Identification.................................................................................... 285
Application....................................................................................... 285
Generator underimpedance protection application.....................285
Setting guidelines............................................................................ 286
Configuration.............................................................................. 286
Settings.......................................................................................286
Full-scheme distance protection, quadrilateral for earth faults
ZMMPDIS (21), ZMMAPDIS (21)......................................................... 290
Identification.................................................................................... 290
Application....................................................................................... 290
Introduction.................................................................................290
System grounding.......................................................................290
Fault infeed from remote end..................................................... 294
Load encroachment....................................................................295
Short line application.................................................................. 296
Long transmission line application..............................................297
Parallel line application with mutual coupling............................. 297
Tapped line application...............................................................303
Setting guidelines............................................................................ 306
General.......................................................................................306
Setting of zone1..........................................................................306
Setting of overreaching zone......................................................306
Setting of reverse zone...............................................................307
Setting of zones for parallel line application............................... 308
Setting of reach in resistive direction..........................................309
Load impedance limitation, without load encroachment
function.......................................................................................310
Load impedance limitation, with load encroachment function
activated..................................................................................... 312
Setting of minimum operating currents.......................................312
Setting of timers for distance protection zones...........................312
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6Transformer protection RET670 2.2 ANSI
Application manual

Additional distance protection directional function for earth faults
ZDARDIR..............................................................................................312
Identification.................................................................................... 313
Application....................................................................................... 313
Setting guidelines............................................................................ 313
Mho impedance supervision logic ZSMGAPC......................................315
Identification.................................................................................... 315
Application....................................................................................... 315
Setting guidelines............................................................................ 316
Faulty phase identification with load encroachment FMPSPDIS (21).. 317
Identification.................................................................................... 317
Application....................................................................................... 317
Setting guidelines............................................................................ 318
Load encroachment....................................................................319
Distance protection zone, quadrilateral characteristic, separate
settings ZMRPDIS (21), ZMRAPDIS (21) and ZDRDIR (21D)............. 320
Identification.................................................................................... 321
Application....................................................................................... 321
System grounding.......................................................................321
Fault infeed from remote end..................................................... 325
Load encroachment....................................................................326
Short line application.................................................................. 327
Long transmission line application..............................................328
Parallel line application with mutual coupling............................. 328
Tapped line application...............................................................335
Setting guidelines............................................................................ 337
General.......................................................................................337
Setting of zone 1.........................................................................338
Setting of overreaching zone......................................................338
Setting of reverse zone...............................................................339
Setting of zones for parallel line application............................... 340
Setting of reach in resistive direction..........................................341
Load impedance limitation, without load encroachment
function.......................................................................................342
Load impedance limitation, with Phase selection with load
encroachment, quadrilateral characteristic function activated ...344
Setting of minimum operating currents.......................................344
Setting of timers for distance protection zones...........................345
Phase selection, quadrilateral characteristic with settable angle
FRPSPDIS (21).................................................................................... 345
Identification.................................................................................... 345
Table of contents
Transformer protection RET670 2.2 ANSI 7
Application manual

Application....................................................................................... 345
Load encroachment characteristics.................................................351
Phase-to-ground fault in forward direction..................................352
Phase-to-ground fault in reverse direction..................................354
Phase-to-phase fault in forward direction................................... 355
Setting guidelines............................................................................ 357
Resistive reach with load encroachment characteristic..............358
Minimum operate currents..........................................................359
Phase selection, quad, fixed angle, load encroachment
FDPSPDIS (21).................................................................................... 359
Identification.................................................................................... 359
Identification............................................................................... 359
Application....................................................................................... 359
Setting guidelines............................................................................ 360
Load encroachment characteristics............................................360
Resistive reach with load encroachment characteristic..............366
Minimum operate currents..........................................................367
High speed distance protection ZMFPDIS (21).................................... 367
Identification.................................................................................... 367
Application....................................................................................... 368
System grounding.......................................................................368
Fault infeed from remote end..................................................... 371
Load encroachment....................................................................372
Short line application.................................................................. 373
Long transmission line application..............................................374
Parallel line application with mutual coupling............................. 375
Tapped line application...............................................................382
Setting guidelines............................................................................ 384
General.......................................................................................384
Setting of zone 1.........................................................................385
Setting of overreaching zone......................................................385
Setting of reverse zone...............................................................386
Setting of zones for parallel line application............................... 387
Setting the reach with respect to load........................................ 388
Zone reach setting lower than minimum load impedance.......... 389
Zone reach setting higher than minimum load impedance.........391
Other settings............................................................................. 392
ZMMMXU settings...................................................................... 395
High speed distance protection for series compensated lines
ZMFCPDIS (21).................................................................................... 396
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8Transformer protection RET670 2.2 ANSI
Application manual

Identification.................................................................................... 396
Application....................................................................................... 396
System grounding.......................................................................397
Fault infeed from remote end..................................................... 399
Load encroachment....................................................................400
Short line application.................................................................. 401
Long transmission line application..............................................402
Parallel line application with mutual coupling............................. 403
Tapped line application...............................................................410
Series compensation in power systems.......................................... 413
Steady state voltage regulation and increase of voltage
collapse limit............................................................................... 413
Increase in power transfer.......................................................... 414
Voltage and current inversion.....................................................415
Impact of series compensation on protective IED of
adjacent lines..............................................................................424
Distance protection.....................................................................425
Underreaching and overreaching schemes................................426
Setting guidelines............................................................................ 433
General.......................................................................................433
Setting of zone 1.........................................................................434
Setting of overreaching zone......................................................434
Setting of reverse zone...............................................................435
Series compensated and adjacent lines.....................................435
Setting of zones for parallel line application............................... 440
Setting of reach in resistive direction..........................................442
Load impedance limitation, without load encroachment
function.......................................................................................443
Zone reach setting higher than minimum load impedance.........444
Parameter setting guidelines...................................................... 445
ZMMMXU settings...................................................................... 448
Power swing detection ZMRPSB (68).................................................. 448
Identification.................................................................................... 448
Application....................................................................................... 449
General.......................................................................................449
Basic characteristics...................................................................449
Setting guidelines............................................................................ 450
Power swing logic PSLPSCH .............................................................. 458
Identification.................................................................................... 458
Application....................................................................................... 458
Table of contents
Transformer protection RET670 2.2 ANSI 9
Application manual

Setting guidelines............................................................................ 460
Scheme communication and tripping for faults occurring
during power swinging over the protected line........................... 460
Blocking and tripping logic for evolving power swings................465
Pole slip protection PSPPPAM (78)......................................................466
Identification.................................................................................... 466
Application....................................................................................... 467
Setting guidelines............................................................................ 469
Setting example for line application............................................471
Setting example for generator application.................................. 476
Out-of-step protection OOSPPAM (78)................................................ 481
Identification.................................................................................... 481
Application....................................................................................... 481
Setting guidelines............................................................................ 484
Automatic switch onto fault logic ZCVPSOF ........................................488
Identification.................................................................................... 488
Application....................................................................................... 488
Setting guidelines............................................................................ 489
Phase preference logic PPLPHIZ......................................................... 490
Identification.................................................................................... 490
Application....................................................................................... 491
Setting guidelines............................................................................ 494
Phase preference logic PPL2PHIZ....................................................... 495
Identification.................................................................................... 495
Application....................................................................................... 496
Setting guidelines............................................................................ 499
Under impedance protection for generators and transformers
ZGVPDIS.............................................................................................. 501
Identification.................................................................................... 501
Application....................................................................................... 501
Operating zones......................................................................... 503
Zone 1 operation........................................................................ 504
Zone 2 operation........................................................................ 504
Zone 3 operation........................................................................ 505
CT and VT positions................................................................... 506
Undervoltage seal-in function..................................................... 506
Load encroachment for zone 2 and zone 3................................ 506
External block signals.................................................................507
Setting Guidelines........................................................................... 508
General.......................................................................................508
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10 Transformer protection RET670 2.2 ANSI
Application manual

Load encroachment....................................................................509
Under voltage seal-in..................................................................510
Section 9 Current protection..............................................................513
Instantaneous phase overcurrent protection PHPIOC (50).................. 513
Identification.................................................................................... 513
Application....................................................................................... 513
Setting guidelines............................................................................ 514
Meshed network without parallel line..........................................515
Meshed network with parallel line...............................................517
Directional phase overcurrent protection, four steps
OC4PTOC(51_67)................................................................................ 519
Identification.................................................................................... 519
Application....................................................................................... 519
Setting guidelines............................................................................ 520
Settings for each step.................................................................522
Setting example..........................................................................526
Instantaneous residual overcurrent protection EFPIOC (50N)............. 531
Identification.................................................................................... 531
Application....................................................................................... 531
Setting guidelines............................................................................ 531
Directional residual overcurrent protection, four steps EF4PTOC
(51N/67N)............................................................................................. 534
Identification.................................................................................... 534
Application....................................................................................... 535
Setting guidelines............................................................................ 537
Common settings for all steps.................................................... 537
2nd harmonic restrain.................................................................539
Parallel transformer inrush current logic.....................................539
Switch onto fault logic.................................................................540
Settings for each step (x = 1, 2, 3 and 4)................................... 541
Transformer application example............................................... 544
Four step directional negative phase sequence overcurrent
protection NS4PTOC (46I2)..................................................................549
Identification.................................................................................... 549
Application....................................................................................... 549
Setting guidelines............................................................................ 551
Settings for each step ................................................................551
Common settings for all steps.................................................... 554
Sensitive directional residual overcurrent and power protection
SDEPSDE (67N)...................................................................................555
Table of contents
Transformer protection RET670 2.2 ANSI 11
Application manual

Identification.................................................................................... 556
Application....................................................................................... 556
Setting guidelines............................................................................ 558
Thermal overload protection, one time constant Fahrenheit/
Celsius LFPTTR/LCPTTR (26)............................................................. 567
Identification.................................................................................... 567
Thermal overload protection, two time constants TRPTTR (49)...........567
Identification.................................................................................... 567
Application....................................................................................... 567
Setting guideline.............................................................................. 568
Breaker failure protection CCRBRF(50BF)...........................................571
Identification.................................................................................... 571
Application....................................................................................... 571
Setting guidelines............................................................................ 572
Stub protection STBPTOC (50STB)..................................................... 575
Identification.................................................................................... 575
Application....................................................................................... 575
Setting guidelines............................................................................ 576
Pole discrepancy protection CCPDSC(52PD)...................................... 577
Identification.................................................................................... 577
Application....................................................................................... 577
Setting guidelines............................................................................ 578
Directional underpower protection GUPPDUP (37)..............................579
Identification.................................................................................... 579
Application....................................................................................... 579
Setting guidelines............................................................................ 581
Directional overpower protection GOPPDOP (32)................................585
Identification.................................................................................... 585
Application....................................................................................... 585
Setting guidelines............................................................................ 587
Broken conductor check BRCPTOC (46)............................................. 591
Identification.................................................................................... 591
Application....................................................................................... 592
Setting guidelines............................................................................ 592
Capacitor bank protection CBPGAPC.................................................. 592
Identification.................................................................................... 592
Application....................................................................................... 593
SCB protection........................................................................... 595
Setting guidelines............................................................................ 597
Restrike detection.......................................................................599
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12 Transformer protection RET670 2.2 ANSI
Application manual

Negativ sequence time overcurrent protection for machines
NS2PTOC (46I2).................................................................................. 600
Identification.................................................................................... 600
Application....................................................................................... 600
Features..................................................................................... 601
Generator continuous unbalance current capability................... 602
Setting guidelines............................................................................ 604
Operate time characteristic.........................................................604
Pickup sensitivity........................................................................ 605
Alarm function.............................................................................606
Voltage-restrained time overcurrent protection VRPVOC (51V)...........606
Identification.................................................................................... 606
Application....................................................................................... 606
Base quantities........................................................................... 607
Application possibilities...............................................................607
Undervoltage seal-in...................................................................607
Setting guidelines............................................................................ 608
Explanation of the setting parameters........................................ 608
Voltage-restrained overcurrent protection for generator and
step-up transformer.................................................................... 610
Overcurrent protection with undervoltage seal-in....................... 610
Section 10 Voltage protection............................................................. 613
Two step undervoltage protection UV2PTUV (27)................................613
Identification.................................................................................... 613
Application....................................................................................... 613
Setting guidelines............................................................................ 614
Equipment protection, such as for motors and generators.........614
Disconnected equipment detection............................................ 614
Power supply quality ..................................................................614
Voltage instability mitigation....................................................... 614
Backup protection for power system faults.................................615
Settings for two step undervoltage protection............................ 615
Two step overvoltage protection OV2PTOV (59)................................. 616
Identification.................................................................................... 617
Application....................................................................................... 617
Setting guidelines............................................................................ 618
Equipment protection, such as for motors, generators,
reactors and transformers.......................................................... 618
Equipment protection, capacitors............................................... 618
Power supply quality...................................................................619
Table of contents
Transformer protection RET670 2.2 ANSI 13
Application manual

High impedance grounded systems........................................... 619
The following settings can be done for the two step
overvoltage protection................................................................ 619
Two step residual overvoltage protection ROV2PTOV (59N)...............621
Identification.................................................................................... 621
Application....................................................................................... 621
Setting guidelines............................................................................ 622
Equipment protection, such as for motors, generators,
reactors and transformersEquipment protection
for transformers.......................................................................... 622
Equipment protection, capacitors............................................... 622
Power supply quality...................................................................623
High impedance grounded systems........................................... 623
Direct grounded system..............................................................624
Settings for two step residual overvoltage protection................. 624
Overexcitation protection OEXPVPH (24)............................................ 626
Identification.................................................................................... 626
Application....................................................................................... 626
Setting guidelines............................................................................ 629
Recommendations for input and output signals......................... 629
Settings.......................................................................................629
Service value report....................................................................630
Setting example..........................................................................631
Voltage differential protection VDCPTOV (60)..................................... 632
Identification.................................................................................... 632
Application....................................................................................... 633
Setting guidelines............................................................................ 634
Loss of voltage check LOVPTUV (27).................................................. 636
Identification.................................................................................... 636
Application....................................................................................... 636
Setting guidelines............................................................................ 636
Advanced users settings............................................................ 636
Section 11 Frequency protection.........................................................637
Underfrequency protection SAPTUF (81).............................................637
Identification.................................................................................... 637
Application....................................................................................... 637
Setting guidelines............................................................................ 638
Overfrequency protection SAPTOF (81)...............................................638
Identification.................................................................................... 639
Application....................................................................................... 639
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14 Transformer protection RET670 2.2 ANSI
Application manual