Pressing test button on the WL family of trip units provides a wide array of check functions to validate the health of the trip system, and the ability of the circuit breaker to trip.  These include:

• Initiating self diagnostic tests on internal circuits “L" (long time trip pickup and delay), "S" (short-time pickup and delay), "I" (instantaneous pickup), and "G" (ground-fault pickup and delay) if installed (ground-fault protection is optional, and may not be included)
• Illuminates LEDs on trip unit to determine whether the LEDs are functioning
• Verify and test the installed rating plug
• Check communication between the circuit breaker's identity module and the trip unit , and
• Perform limited testing on the Rogowski current sensors

This testing can be performed with or without tripping of the circuit breaker.  For more detail on performing internal self-tests, see Chapter 9 of the WL Operator's Manual.  

The latest versions of the WL Operator's Manuals can be found at: 

• UL 1066 WL Circuit Breakers:  Click here
• UL 489 WL Circuit Breakers:  Click here