917:
denote a "ground", hence a "51G" is a time overcurrent ground relay. The "G" suffix can also mean "generator", hence an "87G" is a
Generator Differential Protective Relay while an "87T" is a Transformer Differential Protective Relay. "F" can denote "field" on a generator or "fuse", as in the protective fuse for a pickup transformer. Suffix numbers are used to distinguish multiple "same" devices in the same equipment such as 51–1, 51–2.
923:
For device 16, the suffix letters further define the device: the first suffix letter is 'S' for serial or 'E' for
Ethernet. The subsequent letters are: 'C' security processing function (e.g. VPN, encryption), 'F' firewall or message filter, 'M' network managed function, 'R' rotor, 'S' switch and 'T'
916:
A suffix letter or number may be used with the device number; for example, suffix N is used if the device is connected to a
Neutral wire (example: 59N in a relay is used for protection against Neutral Displacement); and suffixes X, Y, Z are used for auxiliary devices. Similarly, the "G" suffix can
978:
It may surprise some to learn that this standard—or more accurately its AIEE predecessor—is one of the oldest IEEE standards in use. It was first published as AIEE No. 26 in 1928 and was used to document the control systems in the then popular automatic railway
70:-based relays can perform many protective functions in one device. When one device performs several protective functions, it is typically denoted "11" by the standard as a "Multifunction Device", but ANSI Device Numbers are still used in documentation like
993:
Applied
Protective Relaying 1979 by Westinghouse Electric Corporation, 2nd Printing, "Appendix II, Electrical Power System Device Numbers and Functions" as adopted by IEEE standard and incorporated in American Standard
1018:
961:
177:
24 – Volts per Hertz Relay (in some old analog applications, a 59 and an 81 device would be chained together as a 59/81 to implement the equivalent of V/Hz protection)
82:
920:
Device numbers may be combined if the device provides multiple functions, such as the
Instantaneous / Time-delay Overcurrent relay denoted as 50/51.
44:
58:
Many of these devices protect electrical systems and individual system components from damage when an unwanted event occurs such as an
1023:
81:
ANSI/IEEE C37.2-2008 is one of a continuing series of revisions of the standard, which originated in 1928 as
24:
20:
1003:
IEEE Standard for
Electrical Power System Device Function Numbers, Acronyms, and Contact Designations'
942:
75:
71:
53:
Standard for
Electrical Power System Device Function Numbers, Acronyms, and Contact Designations
63:
59:
40:
36:
468:
66 - Notching or
Jogging Device/Maximum Starting Rate/Starts per Hour/Time Between Starts
67:
1012:
582:
87N - Neutral
Differential Protection / Restricted Earth Fault (REF) see also 87RGF
62:. Historically, a single protective function was performed by one or more distinct
285:
46 - Reverse-Phase or Phase
Balance Current Relay or Stator Current Unbalance
384:
52b - AC Circuit Breaker Position (contact closed when circuit breaker open)
777:
C - Capacitor, Condenser, Compensator, Carrier Current, Case or Compressor
381:
52a - AC Circuit Breaker Position (contact open when circuit breaker open)
540:
81R - common industry use for Rate Of Change Of Frequency Relay (ROCOF)
924:
telephone component. Thus a managed Ethernet switch would be 16ESM.
78:
to indicate which specific functions are performed by that device.
360:
51LR - AC Inverse Time Overcurrent (Locked Rotor) Protection Relay
117:
32:
31:
can be used to identify equipment and devices in a system such as
849:
S - Synchronizing, Secondary, Strainer, Sump, or Suction (Valve)
48:
116:
7F - Alternative number for Rate Of Change Of Frequency Relay (
962:"Knowing the Language: The History and Practice of IEEE C37.2"
653:
For specific applications where other numbers are not suitable
647:
For specific applications where other numbers are not suitable
641:
For specific applications where other numbers are not suitable
66:
devices, so each device would receive its own number. Today,
294:
49 - Machine or Transformer Thermal Relay / Thermal Overload
522:
78 - Phase Angle Measuring or Out-of-Step Protective Relay
249:
35 - Brush-Operating or Slip-ring Short Circuiting Device
282:
45 - Atmospheric Condition Monitor (fumes, smoke, fire)
555:
85 - Pilot Communications, Carrier or Pilot-Wire Relay
303:
50BF - Breaker Failure or LBB (Local Breaker Back-up)
101:
3 - Checking or Interlocking Relay, complete Sequence
342:
50/51 - Instantaneous / Time-delay Overcurrent relay
843:
PUTT - Putt: Permissive Underreaching Transfer Trip
840:POTT - Pott: Permissive Overreaching Transfer Trip
549:83 - Automatic Selective Control or Transfer Relay
288:47 - Phase-Sequence or Phase Balance Voltage Relay
336:50Q - Negative Sequence Instantaneous Overcurrent
330:50SG - Sensitive Ground Instantaneous Overcurrent
183:26 – Apparatus Thermal Device, Temperature Switch
159:20 - Electrically-Operated Valve (Solenoid Valve)
315:50IG - Isolated Ground Instantaneous Overcurrent
1019:American National Standards Institute standards
489:67Q - Negative Sequence Directional Overcurrent
486:67SG - Sensitive Ground Directional Overcurrent
291:48 - Incomplete Sequence Relay / Blocked Rotor
180:25 – Synchronizing or Synchronism-check Device
16:System of identifying electrical power devices
324:50NBF - Neutral Instantaneous Breaker Failure
264:39 - Mechanical Condition Monitor (Vibration)
156:19 - Starting-to-Running Transition Contactor
8:
717:RTU – Remote Terminal Unit/Data Concentrator
591:87RGF - Restricted Ground Fault see also 87N
261:38 - Bearing Protective Device / Bearing Rtd
807:F - Feeder, Field, Filament, Filter, or Fan
459:64S - Sub-harmonic Stator Ground Protection
453:64REF – Restricted Earth Fault Differential
573:87L - Segregated Line Current Differential
492:68 - Blocking Relay / Power Swing Blocking
252:36 - Polarity or Polarizing Voltage Device
234:32N - Wattmetric Zero-Sequence Directional
195:27TN - Third Harmonic Neutral Undervoltage
107:5 - Stopping Device, Emergency Stop Switch
83:American Institute of Electrical Engineers
801:DUTT - Direct Underreaching Transfer Trip
570:87GT - Generator/Transformer Differential
438:62 - Time-Delay Stopping or Opening Relay
399:57 - Short-Circuiting or Grounding Device
372:51V - Voltage Restrained Time Overcurrent
354:51C - Voltage Controlled Time Overcurrent
885:TT - Transformer (Tertiary-Voltage Side)
795:DCUB - Directional Comparison Unblocking
624:92 - Voltage And Power Directional Relay
375:51Q - Negative Sequence Time Overcurrent
333:50SP - Split Phase Instantaneous Current
153:18 - Accelerating or Decelerating Device
98:2 - Time-delay Starting or Closing Relay
933:
864:TDDO - Time Delayed Relay Coil Drop-Out
612:88 - Auxiliary Motor or Motor Generator
576:87LG - Ground Line Current Differential
321:50N - Neutral Instantaneous Overcurrent
276:43 - Manual Transfer or Selector Device
174:23 – Temperature control device, Heater
144:15 - Speed or Frequency Matching Device
43:. The device numbers are enumerated in
558:86 - Lock-Out Relay, Master Trip Relay
528:79 - AC Reclosing Relay / Auto Reclose
519:77 - Telemetering Device, Speed Sensor
312:50G - Ground Instantaneous Overcurrent
123:8 - Control Power Disconnecting Device
989:
987:
870:TDPU - Time Delayed Relay Coil Pickup
792:DCB - Directional Comparison Blocking
714:RTD - Resistance Temperature Detector
477:67N - Neutral Directional Overcurrent
471:67 - AC Directional Overcurrent Relay
426:60 - Voltage or Current Balance Relay
327:50P - Phase Instantaneous Overcurrent
267:40 - Field Relay / Loss of Excitation
255:37 - Undercurrent or Underpower Relay
204:27 AUX - Undervoltage Auxiliary Input
7:
941:Kunsman, Steven (December 1, 2011).
876:TH - Transformer (High-Voltage Side)
474:67G - Ground Directional Overcurrent
300:50 - Instantaneous Overcurrent Relay
879:TL - Transformer (Low-Voltage Side)
726:LRSS – Local/Remote selector switch
687:HIZ – High Impedance Fault Detector
681:DME – Disturbance Monitor Equipment
483:67P - Phase Directional Overcurrent
423:59Q - Negative Sequence Overvoltage
306:50DD - Current Disturbance Detector
297:49RTD - RTD Biased Thermal Overload
89:List of device numbers and acronyms
675:DDR – Dynamic Disturbance Recorder
561:87 - Differential Protective Relay
387:53 - Exciter or DC Generator Relay
348:50/87 - Instantaneous Differential
198:27TN/59N - 100% Stator Earth Fault
14:
960:Tengdin, John (1 February 2009).
720:SER – Sequence of Events Recorder
390:54 - Turning Gear Engaging Device
279:44 - Unit Sequence Starting Relay
150:17 - Shunting or Discharge Switch
867:TDO - Time-Delay Opening Contact
861:TDC - Time-Delay Closing Contact
825:MOC - Mechanism Operated Contact
711:RIO – Remote Input/Output Device
630:94 - Tripping or Trip-Free Relay
513:75 - Position Changing Mechanism
501:71 - Liquid Switch, Level Switch
414:59NU - Neutral Voltage Unbalance
402:58 - Rectification Failure Relay
339:50/27 - Inadvertent Energization
210:27/50 - Inadvertent Energization
873:THD - Total Harmonic Distortion
846:R - Reactor, Rectifier, or Room
606:87U - Unrestrained Differential
429:60N - Neutral Current Unbalance
222:31 - Separate Excitation Device
147:16 - Data Communications Device
943:"The Protective Relay Evolves"
702:PDC – Phasor Data Concentrator
621:91 - Voltage Directional Relay
603:87T - Transformer Differential
495:69 - Permissive Control Device
480:67Ns – Earth Fault Directional
363:51N - Neutral Time Overcurrent
351:51 - AC Time Overcurrent Relay
207:27/27X - Bus/Line Undervoltage
171:22 – Equalizer Circuit Breaker
1:
705:PMU – Phasor Measurement Unit
690:HMI – Human Machine Interface
627:93 - Field-Changing Contactor
594:87R - Restrained Differential
531:80 - Liquid or Gas Flow Relay
447:64F - Field Ground Protection
441:63 - Pressure Switch Detector
435:61 - Density Switch or Sensor
432:60P - Phase Current Unbalance
357:51G - Ground Time Overcurrent
138:13 - Synchronous-Speed Device
855:T - Transformer or Thyratron
678:DFR – Digital Fault Recorder
669:CLK - Clock or Timing Source
567:87G - Generator Differential
507:73 - Load-Resistor Contactor
444:64 - Ground Protective Relay
408:59B - Bank Phase Overvoltage
396:56 - Field Application Relay
369:51R - Locked / Stalled Rotor
366:51P - Phase Time Overcurrent
273:42 - Running Circuit Breaker
231:32H - High Directional Power
225:32 - Directional Power Relay
201:27X - Auxiliary Undervoltage
110:6 - Starting Circuit Breaker
756:B - Bus, Battery, or Blower
708:PQM – Power Quality Monitor
420:59X - Auxiliary Overvoltage
309:50EF - End Fault Protection
246:34 - Master Sequence Device
192:27S - DC Undervoltage Relay
1040:
966:Electric Light & Power
747:A - Alarm, Auxiliary Power
723:TCM – Trip Circuit Monitor
609:87V - Voltage Differential
600:87S - Percent Differential
585:87O - Overall Differential
270:41 - Field Circuit Breaker
852:SOTF - Switch On To Fault
798:DD - Disturbance Detector
699:MET – Substation Metering
633:95 – Trip Circuit Healthy
597:87S - Stator Differential
516:76 - DC Overcurrent Relay
462:64TN - 100% Stator Ground
411:59N - Neutral Overvoltage
132:11 - Multifunction Device
129:10 - Unit Sequence Switch
947:Power Grid International
750:AC - Alternating Current
684:ENV – Environmental Data
666:AFD - Arc Flash Detector
579:87M - Motor Differential
552:84 - Operating Mechanism
456:64S – Stator Earth Fault
318:50LR - Acceleration Time
216:29 - Isolating Contactor
189:27P - Phase Undervoltage
113:7 - Rate of Change Relay
810:G - Ground or Generator
588:87PC - Phase Comparison
546:82 - DC Reclosing Relay
504:72 - DC Circuit Breaker
450:64R – Rotor Earth Fault
417:59P - Phase Overvoltage
393:55 - Power Factor Relay
378:52 – AC Circuit Breaker
237:32P - Directional Power
228:32L - Low Forward Power
186:27 – Undervoltage Relay
968:. PennWell Corporation
828:N - Neutral or Network
744:_2 - Negative-Sequence
741:_1 - Positive-Sequence
672:CLP - Cold Load Pickup
618:90 - Regulating Device
564:87B - Bus Differential
405:59 - Overvoltage Relay
219:30 - Annunciator Relay
141:14 - Underspeed Device
21:electric power systems
1024:Electrical components
1005:, IEEE Std C37.2-2008
912:Suffixes and prefixes
837:PC - Phase Comparison
822:M - Motor or Metering
816:H - Heater or Housing
786:D - Discharge (Valve)
543:81U - Under Frequency
165:21G - Ground Distance
135:12 - Overspeed Device
104:4 - Master Protective
25:industrial automation
759:BF - Breaker Failure
735:Suffixes Description
660:Acronyms Description
537:81O - Over Frequency
534:81 - Frequency Relay
243:33 - Position Switch
168:21P - Phase Distance
126:9 - Reversing Device
72:single-line diagrams
789:DC - Direct Current
729:VTFF - Vt Fuse Fail
525:78V - Loss of Mains
240:32R - Reverse Power
213:28 - Flame Detector
162:21 - Distance Relay
29:ANSI Device Numbers
783:CH - Check (Valve)
765:BL - Block (Valve)
696:LGC – Scheme Logic
345:50/74 - CT Trouble
95:1 - Master Element
900:U - Under or Unit
834:P - Phase or Pump
819:L - Line or Logic
813:GC - Ground Check
85:Standard No. 26.
64:electromechanical
1031:
995:
991:
982:
981:
975:
973:
957:
951:
950:
938:
636:96 – Transmitter
615:89 - Line Switch
510:74 - Alarm Relay
258:37P - Underpower
60:electrical fault
37:circuit breakers
1039:
1038:
1034:
1033:
1032:
1030:
1029:
1028:
1009:
1008:
999:
998:
992:
985:
971:
969:
959:
958:
954:
940:
939:
935:
930:
914:
909:
858:TD - Time Delay
693:HST – Historian
91:
51:Standard C37.2
17:
12:
11:
5:
1037:
1035:
1027:
1026:
1021:
1011:
1010:
1007:
1006:
997:
996:
983:
952:
932:
931:
929:
926:
913:
910:
908:
907:
904:
901:
898:
895:
892:
889:
886:
883:
882:TM - Telemeter
880:
877:
874:
871:
868:
865:
862:
859:
856:
853:
850:
847:
844:
841:
838:
835:
832:
829:
826:
823:
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811:
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799:
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787:
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772:
769:
766:
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748:
745:
742:
731:
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724:
721:
718:
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679:
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631:
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619:
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583:
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99:
96:
92:
90:
87:
68:microprocessor
15:
13:
10:
9:
6:
4:
3:
2:
1036:
1025:
1022:
1020:
1017:
1016:
1014:
1004:
1001:
1000:
990:
988:
984:
980:
967:
963:
956:
953:
948:
944:
937:
934:
927:
925:
921:
918:
911:
906:Z - Impedance
905:
903:X - Auxiliary
902:
899:
896:
893:
890:
888:Q - Lube Oil
887:
884:
881:
878:
875:
872:
869:
866:
863:
860:
857:
854:
851:
848:
845:
842:
839:
836:
833:
830:
827:
824:
821:
818:
815:
812:
809:
806:
803:
800:
797:
794:
791:
788:
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779:
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767:
764:
761:
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749:
746:
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739:
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736:
728:
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719:
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635:
632:
629:
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623:
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611:
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584:
581:
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560:
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551:
548:
545:
542:
539:
536:
533:
530:
527:
524:
521:
518:
515:
512:
509:
506:
503:
500:
498:70 - Rheostat
497:
494:
491:
488:
485:
482:
479:
476:
473:
470:
467:
465:65 - Governor
464:
461:
458:
455:
452:
449:
446:
443:
440:
437:
434:
431:
428:
425:
422:
419:
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69:
65:
61:
56:
54:
50:
46:
42:
38:
34:
30:
26:
22:
1002:
979:substations.
977:
970:. Retrieved
965:
955:
946:
936:
922:
919:
915:
780:CA - Cathode
771:BT - Bus Tie
734:
733:
732:
659:
658:
657:
652:
646:
640:
80:
57:
52:
28:
18:
994:C37.2-1970.
804:E - Exciter
774:BU - Backup
768:BP - Bypass
41:instruments
1013:Categories
972:18 October
928:References
891:W - Water
762:BK - Brake
753:AN - Anode
76:schematics
894:F - Fuel
897:G - Gas
831:O - Over
33:relays
651:99 –
645:98 –
639:97 –
118:ROCOF
39:, or
974:2017
49:IEEE
45:ANSI
23:and
74:or
19:In
1015::
986:^
976:.
964:.
945:.
55:.
35:,
27:,
949:.
120:)
47:/
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