Relays for the protection of traction transformers:
Inverse time over current relay as back up protection on primary (HV side) – over current protection of transformer and other equipment.
over current relay on LV side – over current protection of transformer
Overload thermal relay – protection against sustained overloads on transformer
Earth fault relay – earth fault protection of transformer.
Buchholz relay – protection from incipient earth or inter winding faults inside the transformer