| No |
Type of Relay |
| 2 |
Time delay relay |
| 3 |
3 Checking or Interlocking relay |
| 21 |
21 Distance relay |
| 25 |
Check synchronizing relay |
| 27 |
Under voltage relay |
| 30 |
Annunciation relay |
| 32 |
Directional power (Reverse power) relay |
| 37 |
Low forward power relay |
| 40 |
Field failure (loss of excitation) |
| 46 |
Negative phase sequence relay |
| 49 |
Machine or Transformer Thermal relay |
| 50 |
Instantaneous Over current relay |
| 51 |
A.C. IDMT Over current relay |
| 52 |
Circuit breaker |
| 52a |
Circuit breaker Auxiliary switch “Normally open” (‘a ‘contact) |
| 52b |
Circuit breaker Auxiliary switch “Normally closed” (‘b’contact) |
| 55 |
Power Factor relay |
| 56 |
Field Application relay |
| 59 |
Overvoltage relay |
| 64 |
Earth fault relay |
| 67 |
Directional relay |
| 68 |
Locking relay |
| 74 |
Alarm relay |
| 76 |
D.C Over current relay |
| 78 |
Phase angle measuring or out of step relay |
| 79 |
AC Auto reclose relay |
| 80 |
Monitoring loss of DC supply |
| 81 |
Frequency relay |
| 81 U |
Under frequency relay |
| 81 O |
Over frequency relay |
| 83 |
Automatic selective control or transfer relay |
| 85 |
Carrier or pilot wire receive relay |
| 86 |
Tripping Relay |
| 87 |
Differential relay |
| 87G |
Generator differential relay |
| 87G |
T Overall differential relay |
| 87U |
UAT differential relay |
| 87NT |
Restricted earth fault relay |
| 95 |
Trip circuit supervision relay |
| 99 |
Over flux relay |
| 186A |
Auto reclose lockout relay |
| 186B |
Auto reclose lockout relay |
