28 September 2021
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? Product Line:
Powerpact, Masterpact, Micrologic, ZelioResolution:
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 complete 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.