Motor Does Not Start
Likely Cause
Contactor coil not energising, loss of 12V DC to MX-3P, or RS485 communication failure.
How to Fix
- 1Confirm the MX-3P LED is illuminated — if not, check 12V DC power supply.
- 2Confirm Online status in the app before sending a start command.
- 3On start command, check that the MX-3P LED changes state — if not, the RS485 command is not reaching the module. Check gateway RS485 connection.
- 4Measure voltage at the main contactor coil A1–A2 when start is active — should show rated coil voltage. If 0V, check the wire from MX-3P OUT-1 to contactor A1.
- 5Check that the overload relay has not tripped — its NC contact in the coil circuit will prevent the contactor from closing if tripped. Press the overload relay reset button.
- 6Verify three-phase mains supply at contactor input R, S, T — confirm all three phases are present with a multimeter.
Motor Runs in the Wrong Direction
Likely Cause
Phase sequence at motor terminals is reversed.
How to Fix
- 1Wrong rotation on a three-phase motor is corrected by swapping any two motor phase connections.
- 2Isolate the mains supply. Open the motor terminal box.
- 3Swap the U and V motor terminals (or V and W — either pair works). Reclose and restore supply.
- 4Do NOT swap phases at the mains supply input — this affects the phase sequence for all other equipment on the same supply.
- 5After swapping, restart and confirm correct rotation before closing the motor terminal box cover.
Phase-Loss Alarm Triggered
Likely Cause
One or more mains phases absent, phase sense wires not connected, or phase imbalance above threshold.
How to Fix
- 1Check three-phase mains supply at the panel input using a multimeter — confirm R-S, S-T, and R-T voltages are all present and approximately equal.
- 2Check the MX-3P phase sense wires — confirm R, S, T wires are connected to the corresponding sense terminals. Loose or disconnected sense wires cause false phase-loss alarms.
- 3If all phases are present at the mains input but one phase sense reading is 0V: check continuity of that sense wire from the mains bus bar to the MX-3P terminal.
- 4If the alarm triggers intermittently: check for a loose connection at the mains supply incomer or at the MX-3P sense terminal.
- 5Reset the fault latch in the app (Device → Reset Fault) after confirming all three phases are present and stable.
Star-Delta Transition Failure
Likely Cause
Delta contactor not energising, transition timer too short, or transition abort due to current spike.
How to Fix
- 1Check that the MX-3P DELTA output wire is connected to the delta contactor coil A1.
- 2Measure coil voltage at the delta contactor A1–A2 during the transition — if 0V, trace the wire from MX-3P DELTA terminal.
- 3If the motor stalls or trips during transition: increase the star run time by 2–3 seconds (Device Settings → Motor → Star-Delta Timer). The motor may not be up to speed before transition.
- 4Check for mechanical binding in the delta contactor — press the contactor manually to confirm it operates freely.
- 5If the module aborts the transition: reduce the Transition Detection threshold slightly (Device Settings → Motor → Transition Detection) — the current spike at transition may be triggering an abort.
Device Shows Offline in App
Likely Cause
Gateway internet connection lost, RS485 communication break, or 12V DC power failure.
How to Fix
- 1Check gateway Online status in the app — if the gateway is offline, all devices on it will show offline. Restore gateway internet connection first.
- 2If only the MX-3P is offline: check RS485 cable continuity and terminal connections at both ends.
- 3Confirm 12V DC power at MX-3P — check LED. If LED is off, check the 12V DC power supply output and fuse.
- 4Power-cycle the 12V DC supply to the MX-3P — module reconnects within 60 seconds.
- 5Check for loose RS485 terminal screws at the MX-3P and at the gateway — tug wires lightly to test.