46 ALARM — Motor Overheat

If the alarm occurs after operating for a while and the motor is physically hot, verify the load meter and operation pattern. If the load is excessively high or the continuous load torque exceeds 60%, ease the operation pattern or reduce the cutting load. Also check the motor cooling fan; if it is stopped, clogged with dust, or has broken wiring, clean the finger guard or replace the fan/cable.

If the alarm occurs immediately upon power ON, check the detector connectors on the drive unit (CN3 for servo, CN6 for spindle) and the motor side cannon connector. If any connector is loose or disconnected, reconnect it securely.

Turn OFF the main power and wait for the capacitors to discharge. Use a multimeter to check the detector cable for broken wires or connection faults. Replace the detector cable if a fault is found.

Measure the thermal relay terminal conductivity in the motor's cannon connector (e.g., between pins T and V) with a multimeter. If there is no conductivity (high resistance), the thermal protector is defective or permanently open. Replace the motor or detector.

Verify the servo parameter SV034 bit 2 (mohn - motor thermal valid). If the connected motor does not have a thermal protector but this parameter is mistakenly validated, correct the parameter setting.

Ensure that an overload alarm (Alarm 50) was not previously bypassed by forcibly turning the drive unit power OFF. If this was done, wait at least 10 minutes with the cooling fan running to let the motor cool down before attempting to clear the alarm.

Inspect the installation environment. If the ambient temperature is too high, improve panel ventilation. Ensure proper grounding is implemented to prevent noise-induced false thermal errors.

If all wiring, cooling, parameters, and the environment are normal, the hardware is defective. Try connecting the detector to another normal axis. If the alarm remains on the original drive unit, replace the MDS-C drive unit. If it follows the motor, replace the motor.