Issue

My Rack PDU or Rack ATS circuit breaker will not reset or there and/or there is no power output.


Product Line

• Rack Power Distribution Unit (PDU) Models
  • AP95XX
  • AP75XX
  • AP78XX
  • AP79XX
  • AP86XX
  • AP88XX (select models)
  • AP89XX (select models)
  • AP84XX (select models)

• Rack Automatic Transfer Switch (ATS) Models
  • AP7731
  • AP7732
  • AP7753

Environment

• All serial numbers
• Scenarios where one or more groups of outlets are not supplying output power

Cause

A problem has been observed with certain Rack PDU and ATS models that contain rocker-style breakers. Customers are being advised, or are assuming that the Rack PDU is broken because the circuit breaker cannot be reset. All of these devices have multi-position circuit breakers that allow the breaker to trip to a mid-trip position due to overload.

The mid-trip option is intentional and a good feature. It makes it possible, in normal operation, to distinguish between a strip that has overloaded a circuit and tripped its circuit breaker and a circuit breaker that has been intentionally opened. The former case results in a circuit breaker that is half-way open (mid-trip), and somewhat hard to just simply reset (this is deliberate). The latter case shows an actuator that is fully up/out and easy to reset.

It is also possible that jolts and vibrations from shipping can be sufficient to cause the circuit breakers to go the mid-trip position.


Resolution

In order to reset the breakers from the mid-trip position, you must set them to the fully off/tripped position before resetting the breaker. There is a small guard hole below the breaker. You can use a small screwdriver to push the breaker into the fully off/tripped position allowing it to be reset.

The video available below and attachment to this knowledge base article provides detailed instructions on resetting the circuit breaker when it has gone to a mid-trip position.

Published for:APC Belgium