Protective device coordination enhancement for motor starting programs

This work presents an enhancement to motor starting simulation programs which allows them to analyze the motor starting effects on system protective devices. According to a given relay´s operating principle, a method is presented to determine if it will trip by comparing the accumulated energy during the motor starting to the energy needed to trip the relay based on its time current characteristics curve. Under special circumstances, motor starting can cause nuisance tripping of protective devices. Hence, the protective device coordination enhancement presented here can be a useful addition to motor-starting simulation programs.