I went through problem with one of Grasso compressor its W series with 450Kw motor
problem is it is causing the breaker to trip when it shifts itself from star to delta.
Following things checked.
Motor insulation is okay
Cable insulation is okay
Star timing extended and motor working fine
All things contactors, breakers checked,swapped everything fine.
When motor decoupled it was working fine (Shifting properly from star to delta)
Slide calibrations done found normal.
Can anybody help me on it