The Siemens TD500 Secondary Injection Test Set is used to test the Siemens 3VA family of circuit breakers with ETU trip units.

The Siemens TD500 test device can be used to test the different causes of ETU trips. This enables testing of the functioning and wiring of all connected system components before the 3VA molded case circuit breaker is commissioned. During a test the system behaves as it would in the case of a real trip event. The molded case circuit breaker trips when the set delay times expire and signals all alarms and tripped signals from connected components.