Do all protections cause the transformer to trip on both sides?
For distribution transformers used in residential areas, typical protections include:-
Overcurrent & Earth Fault Protection (Electrical) For oil-filled transformers, Gas Protection on the main tank (Buchholz Relay) (Mechanical)
When it comes to high-capacity power transformers used in transmission and generation stations, protections are divided into:
1 Electrical Protections:
1 Differential Protection (87T)
2 Restricted Earth Fault Protection (87N)
3 Overcurrent & Non-Directional Earth Fault Protection (51/51N)
4 Overflux Protection (24) (due to overvoltage or under-frequency)
2 Mechanical Protections:
1 Gas Protection on the Main Tank (Buchholz Relay)
2 Gas Protection on the Tap Changer
3 Overpressure Protection
4 Winding Overtemperature Protection
5 Oil Overtemperature Protection
Common Protection Philosophy:,-
If winding over temperature or Over-Current protection activates, typically only the low-voltage side breaker trips
Some schemes may trip the transformer on both sides in these cases.
