We have the output damaged on a VSD driving a 1200kW cyclone pump on a mine. After three weeks of operation the drive did not restart after it was switched off. The power unit on the white phase had burn marks on and the fuses driving the power unit from the dc bus were open. Can this of been caused by back emf from the motor when stopped? The motor turns backward when stopped from the water header pressure that comes back down after the motor stopped. PS: There is no contactor between the output of the drive and the motor - only at the input.
Please help!!
Please help!!