Motor Does Not Start
Likely Cause
SP-3P contactor not energising, overload relay tripped, or missing three-phase supply.
How to Fix
- 1Confirm the SP-3P MX-3P LED is lit (green or blue). If dark, check 12V DC control power supply.
- 2Confirm Online status in the app before issuing a start command.
- 3On start command, the contactor should click. If no click: check the MX-3P LED changes state during the start — if not, the RS485 command is not reaching the module. Check gateway RS485.
- 4Check for an overload relay trip — the reset button on the overload relay section of the SP-3P may be raised. Press firmly to reset, wait 60 seconds for the relay to cool, then retry.
- 5Confirm three-phase mains supply: measure R-S, S-T, and R-T voltages at the SP-3P input terminals — all should read approximately 415V. Missing phase = motor cannot start.
Motor Runs in the Wrong Direction
Likely Cause
Phase sequence at motor terminals is reversed — correct at motor terminal box, not at supply.
How to Fix
- 1Isolate mains supply at the main switch-disconnector. Prove dead before opening the motor terminal box.
- 2At the motor terminal box, swap any two of the three motor leads (e.g., swap U and V, or V and W).
- 3Do NOT swap phases at the SP-3P supply input R/S/T — this reverses the sequence for all equipment on the supply.
- 4Restore mains, restart from app, and confirm correct rotation before fitting the motor terminal box cover.
- 5For submersible pumps: correct rotation is confirmed by comparing pump output flow — pumping water confirms correct rotation; minimal flow or heating indicates wrong rotation.
Phase-Loss Alarm Triggered
Likely Cause
One or more supply phases absent, phase sense wires disconnected, or phase imbalance above threshold.
How to Fix
- 1Measure R-S, S-T, and R-T voltages at the SP-3P input — confirm all three phase-to-phase voltages are approximately 415V.
- 2Check the MX-3P phase sense wires at the SP-3P assembly — R, S, T sense terminals must be connected. Loose or disconnected sense wires cause false phase-loss alarms.
- 3If all phases present at supply but one phase sense reads 0V in the app: check continuity of that sense wire from the SP-3P input bus bar to the MX-3P sense terminal.
- 4Intermittent phase-loss alarms: check for loose supply connections at the supply incomer, or at the SP-3P R/S/T input terminals.
- 5Reset the fault latch at Device → Reset Fault in the app after confirming all phases are stable.
Overload Relay Trips During Run
Likely Cause
Overload relay FLA dial set too low, motor drawing excess current, or unbalanced loading.
How to Fix
- 1Confirm the FLA dial on the SP-3P overload relay is set to the motor nameplate FLA — not the MCB rating.
- 2Measure motor running current on all three phases with a clamp meter — identify which phase is highest.
- 3If all three phases are within nameplate FLA but the relay still trips: check the overload relay class setting (Class 10 for standard motors, Class 20 for high-inertia loads).
- 4If one phase current is significantly higher than the others (>10% imbalance): investigate for voltage imbalance at the supply, a failed motor winding, or mechanical binding.
- 5For motors with repeated unexplained trips at correct FLA setting: fit a current event logger to capture the current profile at the moment of trip — the motor may be experiencing locked-rotor or blocked-rotor events.
Device Shows Offline in App
Likely Cause
Gateway internet connection lost, RS485 cable fault, or 12V DC power failure.
How to Fix
- 1Check gateway Online status — if the gateway is offline, all its devices show offline. Restore gateway internet first.
- 2If only the SP-3P shows offline: check RS485 terminals at the SP-3P assembly and at the gateway.
- 3Confirm MX-3P LED is lit on the SP-3P assembly. If dark: check 12V DC power supply.
- 4Power-cycle the 12V DC control supply to the SP-3P — module reconnects within 60 seconds.
- 5Tug RS485 terminal wires lightly at both ends — a loose screw terminal is the most common RS485 fault.