Ungrounded Vs Grounded WYE In Transformer Primary

Home work alert!

At least have the decency to tell us what you think it is and we can correct you.

Effort man, effort!

Hi Smith,

Say If a fault between the breaker at the upstream of the transformer and the transformer (YNd11) with Y solidly grounded) should occur, would the fault current flow into the neutral of the transformer or to the source ground ?

Would the residually connected CT work for ground faults if the neutral is ungrounded?

It depends on the fault, Mildred. If the transformer is correctly protected then it will be deenergised before any damage is done.

I think the short-circuit current will be divided-according to each path impedance-into 2 parts: one through transformer neutral and second to remote system neutral. What do you think?

If the System is -well- grounded then if a short-circuit occurs downstream the CT a current will flow from the grounded phase conductor to the remote grounding point of the System and then the sum of currents of all phases will be the grounding current-it does not important if the neutral of the transformer connected downstream the CT is grounded or not.

How did you answer this interview question?