Hybrid switch to suppress the inrush current of AC power capacitor

This paper proposes a hybrid switch to suppress the inrush current of an ac power capacitor. This hybrid switch consists of a thyristor switch and an electromagnetic switch connected in parallel. The thyristor switch is used as an auxiliary switch during the transient state of turning on and turning off the ac power capacitor, and the electromagnetic switch is used as the main switch in the steady state. The proposed hybrid switch can avoid the inrush current of the ac power capacitor in the process of turning on and avoid the electrical arc in the process of turning off. The current rating of the thyristor switch and the electromagnetic switch used in the proposed hybrid switch is very small compared with a conventional thyristor switch or an electromagnetic switch used for switching ac power capacitor individually. Moreover, the proposed hybrid switch can extend the life of the ac power capacitor and the electromagnetic switch. A prototype is developed to demonstrate its performance. The test results show that the proposed hybrid switch module for ac power capacitor has the expected performance.