What do the indication lights on the Micrologic trip units mean?


28 September 2021

Trip indicator lights on Micrologic

Product Line:
Circuit Breakers

The Ir long time pickup level was exceeded.
Isd/ Ii:  The Isd short time pickup or the Ii instantaneous pickup was exceeded.
Ig:   The Ig ground fault pickup was exceeded.
Ap:   The self-protection indicator light lights when the trip unit causes the breaker to trip for a reason other than an overcurrent on the Ir, Ii, Isd, or Ig functions. 
The Ap light can indicate:
* issue with internal current sensors, usually moisture or corrosion
* instantaneous override level is exceeded
* fail-safe protection for circuit in case of trip unit malfunction
* trip unit temperature approaches 90°C
* overvoltage on 24 Vdc inputs F1-F2

Related Links
FA176046: Determining the cause of breaker tripping with Ap light indication on the Micrologic trip unit
Instruction Bulletin 48049-136-05:  Micrologic 2.0A, 3.0A, 5.0A, and 6.0A Electronic Trip Units