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