The VFD sized to deliver 150HP at 380V should be a 245A (for example to ABB ACS550-U2-245A-4) unit, will require a 250A fuse (fast acting) and 350MCM cable. Same VFD can deliver 200HP at 480V.
nRaju,
Is this the first time that the transformer and the relay are commisioned that you are having problem, or have they been in service for a while and the problem started only now? If this is the first time for this transformer and the relay, the problem has to be in the wiring and/or the...