How should a sudden motor stoppage in a high-mast light be handled?
If the lifting motor of a high-mast light stops suddenly during operation, the possible causes and emergency handling procedures are as follows:
1. Thermal overload relay trip: Prolonged motor overload or poor heat dissipation causes the thermal relay to trip. Wait for the motor to cool down (approximately 15–30 minutes), then press the thermal relay reset button. Simultaneously, check for mechanical jams that might be causing the overload.
2. Phase loss or low voltage: Use a multimeter to measure the three-phase voltage at the motor input terminals (for 380V three-phase motors). If a phase is missing, check the upstream circuit breaker, contactor, and cable connections. If the voltage is too low (below 90% of the rated voltage), check if the power supply line is undersized or excessively long.
3. Motor winding burnout: If there is a smell of burning or the winding-to-ground insulation resistance measures zero, the motor has burned out. The motor must be replaced with one of the same model.
4. Limit switch malfunction: The light array may have triggered the upper or lower limit switch, causing the control circuit to cut off. Check if the limit switch position is correct and manually reset the switch (if applicable).
5. Control button or contactor failure: Button contacts may be oxidized, or the contactor coil may be damaged. Test by temporarily short-circuiting the button terminals with a wire; if the motor starts, replace the button.
6. Emergency stop button pressed: Check if the emergency stop button is engaged and rotate it to reset. After the motor stops, ensure the light array is in a safe position (if it is suspended in mid-air, use the manual crank to lower or raise it into place to avoid prolonged suspension). Then, troubleshoot the causes listed above one by one. Personnel unfamiliar with electrical repairs should not attempt to disassemble the motor themselves; instead, contact a professional electrician or the manufacturer's after-sales service.
