Three phase transformer connections.

[prc]

In a grid system, distribution system is fed from 132/11Kv star/star solidly grounded system.11Kv system feed to loads through 3 phase 3 limbed core type distribution transformers of delta/solidly grounded star connection.Now the utility plans to use 3 single phase shell type (wound core ) transformers to get 3 phase solidly grounded star/grounded star connection.Of course this secondary load will be isolated from former loads to take care of phase shift.Any problem in this application? Any special precautions to be taken?

 

[alehman]

I don't think will be any difference. If the impedance is different, you may need to review protection.

 

[sanchezjl]

Definitely, you need to review your relay coordination, since the delta was a filter to the high side world of zero sequence faults (L-G or LL-G) on the star side, but if now you are going to have star-star solidly grounded on both sides, you are going to have a path for this currents, and threfore, you need to coordinate the ground relays.

Good luck!

 

[davidbeach]

What sanchexjl said. Your zero-sequence relaying will need to be reevaluated.