Last month, we got our 1000 HP 6.6 KV motor cleaned after 6 years of operation. When the motor was run, it gave whitish smoke. Motor was stopped immediately (it ran for appr. less than a min). Megger results were showing the motor to be OK.
We called the service guys who have cleaned the motor...
Recently, on our 12.5 MVA, 15.5 / 6.9 KV Dyn1 transformer, differential relay operated while changing the taps.
The transformer has 17 taps position i.e., +8, .., 0, ..., -8 with a regulation of 10 % voltage.
The incident happened when the operator was changing the tap from -7 to -8 position...
