The relay pulls in but the motor does not turn, where is the problem?
If the relay pulls in, the radio link and the receiver are sound; the problem is in the power circuit after the relay contact. In order, check the contactor coil voltage, the limit switch NC contacts, the thermal overload relay, phase loss, the motor terminal connections, and whether the brake releases. A burnt or welded relay contact gives a similar symptom too.
This symptom has already halved the fault: the remote control, the receiver and the pairing are working. The remaining area is the path from the relay contact to the motor.
Order of checks:
- Is the relay contact really conducting? Even if you hear the relay, the contact may be burnt by arcing or have a high resistance. Measure the voltage drop across the contact. If there is no snubber/diode on an inductive load, this fault is typical.
- Is there voltage on the contactor coil? If there is and the contactor does not pull in, the coil is faulty or mechanically jammed.
- Limit switch NC contacts. The limit switch goes in series with the power circuit; a switch that has hit its limit or is faulty locks the movement. Check whether the other direction works — if only one direction works, the limit is a strong suspect.
- The thermal overload relay / motor protection breaker may have tripped.
- Phase loss or phase sequence. On a three-phase motor, if one phase is missing the motor hums, does not turn and heats up quickly; cut the power immediately.
- Brake. If the electromagnetic brake does not release, the motor is strained and does not turn. Check the brake supply circuit separately.
- Interlocking. An incorrectly built electrical interlock can block both directions.
Carry out the measurements with authorised personnel and appropriate personal protective equipment.
The full topic: Wireless remote control installation: pairing, relays, safety