The features of 0.4 kV motor interruption by a vacuum contactor with different contact materials

Computer aided modelling has been used to simulate current chopping behaviour at different current levels. This model is based on the known are life time of a DC current. The appropriate experimental research has been carried out for a batch of 35 industrial VI with CuCr contacts. The obtained dependencies of the average arc life time VC current show a certain technological scatter that has been taken into account in further chopping current simulations. The developed software has been used to analyze features of 0.4 kV motor interruptions by low voltage vacuum contactor with CuCr and AgWC contacts (low-surge contact material). The obtained results have been generalized in "safe operation regions" that allow us to consider the necessity of the surge suppression when low voltage vacuum contactors are applied to motor control.