Mitsubishi Electric · R410A Systems
The anti-phase device has detected an incorrect phase sequence (requiring two phases to be swapped) or an open circuit in the L2 phase of the main power supply (specifically on the primary side of the contactor). This can lead to motor damage.
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Verify phase rotation of the incoming 3-phase power supply at the main terminals using a phase rotation meter.
Measure voltage between L1-L2, L2-L3, and L3-L1 on the primary side of the main contactor — expect balanced 3-phase voltage.
Check the main contactor's L2 terminal for secure connection and proper operation.