I new here at the forums. I have a situation in an office building I'm handling. Just want to know if someone could help me out. Here's the problem: 3 units of 160 KVA SOCOMEC UPS connected to 3 units 200KVA 3 phase 4 wire 460V/380V transformer connected in parallel. Configuration is attached. Now, when we try to connect a new 80 KVA UPS to the 200KVA transformers then add three more feeder lines, and put the three 160KVA UPS to the 400KVA transformer,one of the 200KVA transformer gets burned. Basically, we want to isolate an area because of harmonics, that's why we did this. Just want to know the cause of this so as to prevent it from happening again.