Appendix 2
ANSI/IEC RelaySymbols
There are two methods for indicating protection relayfunctions in common use. Oneis given in ANSIStandardC37-2, and uses a numbering system for variousfunctions. The functions are supplemented by letterswhere amplification of the function is required. Theother is given in IEC60617, and usesgraphical symbols.Toassistthe Protection Engineerin converting from onesystemto the other,a select list of ANSIdevicenumbersand their IECequivalents is given in FigureA2.1.
FigureA2.1 - ANSInumber/IECsymbol
Net W 0r k Pro tee t ion &.A u tom a t ion G u ide . 467 .
Description ANSI IEC60617 Description ANSI IEC60617
Overspeedrelay 12 EJ Inversetime earthfault 51G1/*>,1overcurrentrelay
Underspeedrelay 14 Definitetime earthfault 51N I,,Iovercurrent relay
Distance relay 21 Voltage restrained/controlled 51Vovercurrent relay
Overtemperature relay 26 Power factor relay 55 ICDSrp > IUndervoltagerelay 27 [B Overvoltagerelay 59
Directionaloverpower 32 Neutralpointdisplacement 59N IUrsd > Irelay relay
Underpowerrelay 37 Earth-faultrelay 64 II> IUndercurrentrelay 37 Directionalovercurrentrelay 67
Negativesequencerelay 46 EJ Directionalearthfault relay 67N IINegativesequencevoltage 47 PhaseangIerelay 78 Brelay
ThermaI relay 49 [}] Autorecloserelay 79 I?IInstantaneousovercurrent 50 B Underfrequencyrelay 81U Grelay
Inversetime overcurrent 51I,,I Overfrequencyrelay 810 [E]relay
Differentialrelay 87 G