Capacitive Load Switching: Identifying and Increasing Military and Aerospace Power Systems Reliability 2012-01-2184

This paper will illustrate how the increasing electrical demands to power military and aerospace applications can successfully be met by high performance electromechanical relays. To meet these higher demands engineering compatibility must be properly understood between the intended application and relay switching performance parameters. With high performance electromechanical relays continuing to play a critical part in military and aerospace applications it is more important than ever before that engineers capture all of the military and aerospace electrical power requirements.

A critical area within powering military and aerospace systems is capacitive load switching. Capacitive loads can generate high current levels that are transient in duration and adversely affect the relay at the component level and the military or aerospace applications at the higher systems levels. As capacitance increases the amplitude and duration of the current transient also increase. Often these transients, while brief in nature, can dramatically exceed the steady-state or overload switching ratings in a high performance electromechanical relay. Identifying the properly rated relay and adapting the circuit to meet the capacitive load with the use of negative temperature coefficient resistive devices requires detailed understanding of the capacitive loads to be switched.

When capacitive loads are properly identified and matched to the relay it will deliver a higher degree of application-relay compatibility. The increased functionality, performance, reliability and quality the customer will experience delivers desired functionality and performance under demanding military and aerospace conditions.