Coordination of Varistors With Transient Voltage Suppression Diodes in Automotive DC Systems

The coordination of metal-oxide varistors with transient voltage suppression diodes commonly employed for the protection of sensitive electronic equipment in DC automotive systems is experimentally investigated. Double-exponential impulse currents adopted in relevant standards, concave and rectangular impulse currents resembling field records on lightning-related surge events, as well as temporary overvoltages, are employed to stress the surge protective components and evaluate their coordination. Experimental results and the subsequent analysis reveal that effective coordination of varistors with bidirectional diodes can be a challenging task, especially under long-duration and high-energy electromagnetic pulses. Under such conditions, the safety and uninterrupted operation of vehicles containing low-voltage electrical circuits with embedded sensitive electronic equipment is threatened.