Abstract:

AC contactors operating under low control circuit supply voltage often exhibit unsteady closing faults,which may critically compromise the reliability and safety of client-controlled equipment.Simulation analysis of the attraction-counterforce characteristics reveals that the root cause of unsteady closing lies in the counterforce exceeding the attraction force.Fault simulation experiments under low control circuit supply voltage indicate that unsteady closing during operation can trigger severe issues such as contact adhesion,phase loss,or even short circuits in AC contactors.Improvement suggestions are proposed from three aspects:design optimization of contactor attraction-counterforce characteristics, contactor selection, and improvement of equipment control circuits.

Key words: unsteady closing faults, low control circuit supply voltage, characteristics of attraction force and reactive force, contactor selection, enhancements to equipment control circuits