AC-410 Phase Sequence Loss Monitor

About the AC-410 Phase Sequence Loss Monitor from the ATC Diversified Electronics division of Marsh Bellofram:

This internal control relay drops out and a 3 minute delay-on-break time delay begins. This delay is used to lock out the compressor, allowing time for head pressure to equalize. When the delay has completed, the relay will re-energize provided all conditions are corrected and the external control voltage is present on terminals six (6) and seven (7). A green indicator glows when all line conditions are normal and a red indicator shows when the timer is in its delay.



  • Protect 3 phase refrigeration equipment from adverse line conditions, such as:
    • Phase Loss (Single Phasing): When any one phase drops to 83% or less of the adjustment setting.
    • Under Voltage (Brown Outs): When all three phase voltages drop to 90% or less of the adjustment setting.
    • Phase Reversal (Improper Sequence): When the wrong sequence is applied to the equipment.