34.5kV wye-grounded / 13.8 wye-ungrounded 3 phase Transformer
34.5kV wye-grounded / 13.8 wye-ungrounded 3 phase Transformer
(OP)
I work for a utility which uses wye wye solidly grounded distribution transformers for 99.9% of our customers, though we have one customer who has requested to have their parallel 10MVA transformers with the secondaries ungrounded. We will be installing 34.5kV/13.8kV 2 - 10MVA transformers. I was wondering what could be the potential risks with this configuration, also if you have experience with this configuration could you give me some pointers on any issues you had/have with these transformers? Thanks in advance for your time and assistance.






RE: 34.5kV wye-grounded / 13.8 wye-ungrounded 3 phase Transformer
I would either make sure that there is not a situation where you might end up with no earth on the transformer secondary (e.g., downstream circuit breaker open, removing the earthing transformer from the transformer secondary system), or that you have some other method of detecting an earth fault (e.g., 3V0 protection). Care needs to be taken with regards to any connections - including LV, protection, control and communications circuits - into the customer site.