Frequently asked questions
What do the indication lights on the Micrologic trip units mean?
FA234513
28 September 2021
Issue:
Trip indicator lights on Micrologic
Product Line:
Circuit Breakers
Resolution:
Ir: 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
