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Is it possible to use the Micrologic trip unit on a Powerpact or Masterpact circuit breaker to provide phase loss, phase reversal, or phase imbalance protection?

FA102268

23/03/2019

Issue:
Is it possible to use the Micrologic trip unit on a Powerpact or Masterpact circuit breaker to provide phase loss, phase reversal, or phase imbalance protection? Might be specifically looking at the Power and Harmonic Micrologic trip units, which have some features that seem similar to phase loss proteciton

Product Line:
Powerpact, Masterpact, Micrologic, Zelio

Environment: 
Molded Case Circuit Breakers, Insulated Case Circuit Breakers, Phase Failure Relays

Cause:
Application Assistance

Resolution:
No. While the Power and Haromonic trip units used in Powerpact P and R and Masterpact NT and NW breakers do have some voltage protection features, they cannot be used as phase loss protection, as neither the Minimum Voltage Protection or the Voltage Unbalance Protection can detect the loss of a phase. 

If phase loss protection is needed in these breakers, here is what is required:
 - A Phase Measurement Relay with the desired protection features
 - A breaker or switch with a shunt trip to open and close the circuit

An undervoltage relay could also be used to detect a total power loss or drop, but it would at most be able to monitor voltage on two phases. If there was a voltage loss/drop on the third phase, the undervoltage trip would be unable to detect it.

For Masterpact MTZ with the Micrologic X control unit it is possible to provide Phase loss and undervoltage protection when the ANSI27 digital module is purchased. It can then be set to alarm or trip the breaker when either 1 phase (ANSI27-1)  or all 3 phases (ANSI27-2) drop below Vmin.