Transformer faults to consider

Sandeep_EK99 · ‎2022-06-30

Hello the Experts,

Could you tell me please what are the different kinds of faults to be taken into account for the protection of a transformer?

BR

Sandeep EK

D_Samiparna · ‎2022-07-01

A fault could occur in three zones on the transformation circuit: the MV side, the transformer itself and the LV circuit housed between the transformer and the LV protection.

On the MV side, this consists in protecting the network. The "protection transformer" must stop the opening of the power supply substation circuit breaker in order to ensure continuity of service.

In general, when the fault occurs inside the transformer, it is not economically viable to carry out repairs. Therefore, this protection prevents danger to persons. The default current must be cut before an external signs appear.

Tests have shown that in order to avoid and external signs, the short circuit must not last more than 0.1 to 0.2 sec depending upon the level of current.

When the fault occurs on the LV side, between the transformer and the LV protection, the default current on the LV side is rather weak, between 10 and 20 times the nominal current.

See Answer In Context

D_Samiparna · ‎2022-07-01

A fault could occur in three zones on the transformation circuit: the MV side, the transformer itself and the LV circuit housed between the transformer and the LV protection.

On the MV side, this consists in protecting the network. The "protection transformer" must stop the opening of the power supply substation circuit breaker in order to ensure continuity of service.

In general, when the fault occurs inside the transformer, it is not economically viable to carry out repairs. Therefore, this protection prevents danger to persons. The default current must be cut before an external signs appear.

Tests have shown that in order to avoid and external signs, the short circuit must not last more than 0.1 to 0.2 sec depending upon the level of current.

When the fault occurs on the LV side, between the transformer and the LV protection, the default current on the LV side is rather weak, between 10 and 20 times the nominal current.