Troubleshooting for Overheating And Shutdown of Fume Hood Motor

Troubleshooting for overheating and shutdown of Fume hood motor

Power supply and voltage inspection

Voltage stability check: Use a voltmeter to check whether the power supply voltage is balanced and appropriate. When the instantaneous voltage of the motor exceeds the rated voltage by more than 10% or is lower than the rated voltage by more than 5%, it will cause the motor to heat up and its temperature to rise under the rated load, which may eventually lead to a shutdown. If the power supply voltage is too high or too low, the power supply should be adjusted or other measures should be taken to restore the voltage to normal, ensuring that the power supply voltage fluctuates within the allowable range of the motor's rated voltage.

Troubleshooting for phase loss issues: Contact problems with the power switch of the motor and an open circuit in one phase fuse can both cause phase loss operation, leading to an increase in the motor's temperature. Check the power line to see if there is a phase power outage caused by other equipment failure, and whether the other three-phase equipment connected to this line is operating with a missing phase. Check whether one phase of the circuit breaker or contactor is burned out due to bias voltage or has a phase loss caused by poor contact. Check whether the motor's incoming line is missing a phase due to aging, wear or other reasons. Check whether one phase winding of the motor is open-circuited or whether one phase connection in the junction box is loose.

Load and mechanical fault troubleshooting

Load condition check: If the motor operates under overload for a long time, it will cause excessive current, generating a large amount of heat and leading to motor overheating and shutdown. Check whether the load borne by the motor is too heavy and whether it exceeds its design range. If the motor overheating is caused by excessive load, the load should be appropriately reduced to bring it back within the design range. This can be achieved by changing the transmission device or reducing the force on the motor to lower the load.

Mechanical fault detection: Motor vibration can lead to problems such as bearing wear and loose fasteners. In severe cases, it may even affect the normal operation of the motor, causing it to overheat. Check whether the mechanical parts are stuck or have excessive friction, such as whether the motor bearings are damaged, whether the rotor is unbalanced, and whether there is a poor match between the stator and rotor, etc. If the bearing is severely worn, it will cause significant friction and generate heat. It is necessary to check whether the bearing is loose and replace the worn bearing in time.

Troubleshooting of the heat dissipation system

Heat dissipation condition check: Poor heat dissipation inside the motor may be caused by reasons such as fan damage or blocked ventilation ducts, which can lead to ineffective heat dissipation and cause the motor to overheat and shut down. Observe the working environment of the motor, including ventilation conditions and surrounding temperature, to see if it has an adverse effect on the motor's heat dissipation. Make sure there is sufficient space around the motor for air circulation and clear any obstacles that may impede air flow.

Heat dissipation equipment inspection: If the motor is equipped with a heat dissipation fan, check whether the fan is operating normally. If there is a fault, it should be repaired or replaced in time. Add ventilation equipment or adopt other heat dissipation measures, such as adding cooling fans or setting up heat sinks around the motor. Check whether there is any dirt blocking the air inlet or outlet of the motor and whether the heat dissipation fins are damaged or not.

Troubleshooting of internal motor faults

Winding problem inspection: Inter-turn or phase-to-phase short circuit or grounding of the stator winding of the motor will cause the current of the motor to increase and result in a temperature rise. Check the insulation resistance between the two-phase windings with a megohmmeter or multimeter. The current of the three-phase windings can be checked by the current balance method. The phase with the larger current is the short-circuit phase. A short-circuit detector can also be used to check whether there is a short circuit between the turns of the windings. If there is a short circuit, insulation can be added to the center or the winding can be directly replaced. If the bars of the squirrel-cage rotor of the motor break or the coil joints of the wound rotor become loose, it will cause an increase in the current of the maintenance network and lead to temperature rise. The solution is to weld and repair or replace the rotor.

Insulation condition inspection: Aging or damage to the insulation performance of the motor will directly lead to heating problems. Regularly inspect the insulation condition. The insulation to ground should be measured weekly and be greater than 0.5MΩ. The three-phase unbalance degree in a quarter should be less than 2%, and the annual partial discharge should be less than 20pC. Replace aged components in a timely manner.

Investigation of operation and maintenance conditions

Operation status monitoring: Install temperature sensors and current monitoring devices to monitor the motor temperature and operating current in real time. These data can help identify potential problems in a timely manner and take measures to intervene.

Maintenance condition inspection: Regularly inspect and maintain the motor, including checking bearing wear, lubrication conditions, insulation status of windings, etc. Regularly carry out cleaning and maintenance work to ensure that the motor is in good working condition. For instance, during monthly inspections, clean the dust accumulated on the heat sinks (shorten the cycle when the dust concentration is high), and during quarterly inspections, replace the bearing grease.