High Reliability magnetic contacts usually must endure a minimum of 1 million cyles, maybe more depending upon the application, under full load before Under Writers will approve insurance policies for particular installations. Testing is a requirement of all approval agencies.

This device is a reciprocating shaft with an arbitrary permanent magnet positioned under the switch test pedestal. The solenoid is controlled by an embedded microprocessor. Switches fail either open or closed. If a command is given to close the contacts and the contacts do not make electrical contact, the switch fails open. If a command is given to open the contacts and electrical contact is not broken, the switch fails closed. The microcomputer checks for these conditions and issues one count, if it passes cycle by cycle.

The load to the magnetic contacts is preset for each test. The voltage across the switch is set independently of a constant current source driving the switch. This insures that the same electrical conditions are met each cycle.

Power supplies and electronic counters are not shown here. The operation of the device is programmable.