Arc discharge and surge suppression during a breaking operation of a magnetic relay

In a switching circuit with an inductive load, arc discharge and surge generated during a breaking operation are big problems. We proposed an electric method for arc discharge suppression using a timely controlled transient current switch and a capacitor arranged in parallel to the energizing switch. In this paper, we propose an improvement. We replaced the capacitor with two capacitors. One to suppress arc ignition and the other is to suppress surge. Using electrical measurements of the relay contact operation, adequate capacitance values and series resistance were derived numerically. The capacitance to suppress arc ignition does not depend on load inductance but only on load resistance. However, the capacitance and its series resistance to suppress surge depend on the load inductance and its resistance. For the break operation (50 V/8 A) of a conventional magnetic relay (HH62P) with an inductive load (84 mH), a 1muF capacitor can suppress arc ignition and a 100 muF capacitor and a resistance of 8Omega is sufficient to suppress surge. No arc ignition and surge controlled to less than 30 V were confirmed experimentally.