Proposed test program to evaluate the impact of mid-cycle reversals on MOV feed breakers and thermal overload devices

A test program has been initiated to determine the response of a motor-operated valve (MOV) to a mid-cycle reversal. Reversal of the main line contactors can create an internal voltage value of up to 2.0 per unit. There are several known examples of the resulting currents causing trips of the MOV´s supply breaker on magnetic, instantaneous overload. Testing is intended to determine the locked rotor current values as a function of supply voltage, the resulting waveforms, and decay constants. Results of testing could be used to determine the optimum breaker settings, along with minimum delay times to impose on sequential operations of the MOV. Future testing should also determine the impact of the transient on thermal overload devices. The actual testing has been delayed beyond the scheduled date for publication of this paper. The test program is described, including its purposes, methodology, and expected results