High speed motors, with their characteristics of high speed and high power density, are widely used in fields such as machine tool spindles and precision transmission systems. However, during operation, if the temperature rise exceeds the rated range (usually 40-60 ℃ higher than the ambient temperature is considered abnormal), it can easily cause insulation aging, bearing damage, power loss and other faults. The process of "emergency stop loss root cause investigation system repair" needs to be followed to accurately solve the temperature rise problem and restore normal motor operation.
1、 First, take emergency measures to avoid the escalation of the malfunction
When the temperature rise of the high-speed motor is detected to be too high (such as through temperature sensor alarm or obvious overheating of the shell touch), emergency measures should be taken immediately:
Immediately stop the machine and cut off the power, allowing the motor to cool naturally to ambient temperature to avoid further damage to the insulation layer or bearing jamming caused by high temperatures; During the cooling process, it is forbidden to directly rinse the motor casing with cold water to prevent deformation of the motor casing due to excessive temperature difference; At the same time, check the surrounding environment of the motor, remove debris that hinders heat dissipation (such as dust accumulation and obstructions), and create a safe environment for subsequent inspections. If the motor has experienced serious malfunctions such as abnormal noise and smoke due to high temperature, the main power supply should be disconnected to avoid the risk of short circuit or fire.
2、 Root cause analysis: finding the reason for the imbalance between heat generation and heat dissipation
The essence of excessive temperature rise in the motor is that "heat generation exceeds heat dissipation", and it needs to be investigated in both directions from the heat generation end and the heat dissipation end:
1. Abnormal heat generation end: excessive load and internal losses
Firstly, load overload is a common cause. If the actual operating load of the motor exceeds the rated power (such as excessive cutting of the machine tool spindle or stuck transmission system), it will cause an increase in stator current, intensified copper loss, and rapid accumulation of heat; Secondly, internal faults in the motor can cause additional losses, such as inter turn short circuits in the stator winding and broken rotor bars, which can result in uneven current distribution and local high temperatures; In addition, bearing wear (such as ball peeling and lubrication failure) increases frictional resistance and generates frictional heat, especially during high-speed operation where the frictional temperature rise is more pronounced.
2. Failure of heat dissipation end: unable to effectively dissipate heat
A malfunction in the cooling system can lead to heat accumulation. If the built-in cooling fan of the motor is damaged (such as broken fan blades or motor jamming), or if the cooling air duct is blocked (dust or oil covering the cooling fins), it will block the forced air cooling path; For water-cooled high-speed motors, if the cooling water pipeline is blocked or the water pump fails, it will cause interruption of the cooling water circulation and a sudden drop in heat dissipation efficiency; In addition, poor ventilation in the installation environment of the motor (such as enclosed spaces and high-temperature environments) can also lead to high ambient temperatures, reduced heat dissipation temperature differences, and inability to naturally dissipate heat.
3、 Targeted repair: Develop solutions based on the causes
1. Solve the problem of heat generation: reduce losses and loads
If it is a load overload, it is necessary to recalculate the actual load of the motor, adjust the operating parameters of the equipment (such as reducing the cutting depth of the machine tool, reducing the transmission speed), and ensure that the load is controlled at 80% -90% of the rated power; If the load cannot be reduced, it is necessary to evaluate whether to replace the motor with a higher power to avoid long-term overload operation.
If it is an internal fault of the motor, the motor needs to be disassembled for inspection: when the stator winding is short circuited, measure the winding resistance with a multimeter, replace the damaged winding coil, and re coat the insulation with paint; The broken rotor bar requires replacement of the rotor assembly; If the bearing wears out, it needs to be replaced with high-precision bearings of the same model, and high-temperature resistant lubricating grease (such as lithium based grease) should be supplemented to ensure smooth operation of the bearing and reduce frictional heat generation.
2. Repair the cooling end: restore the cooling channel
For air-cooled motors, replace the damaged cooling fan, blow the heat sink and air duct with compressed air to remove dust and oil stains; If the heat sink is severely corroded, it can be sprayed with heat dissipation coating to improve the heat conduction efficiency.
For water-cooled motors, disassemble the cooling water pipeline and use high-pressure water guns or specialized cleaning agents to clear blocked pipelines; Check the operation status of the water pump and replace the faulty water pump or motor; At the same time, check the quality of the cooling water. If the water is turbid, replace the coolant to avoid the deposition of scale that affects heat dissipation.
In addition, optimize the installation environment of the motor: install exhaust fans or industrial air conditioning in enclosed spaces to ensure that the ambient temperature is below 35 ℃; Avoid placing the motor near heating equipment to reduce the impact of external heat sources.
4、 Verification and Prevention: Ensuring Long term Stable Operation
After repair, no-load and load tests are required: run the motor without load for 30 minutes, use an infrared thermometer to detect the temperature of the motor housing, bearings, and windings, and confirm that they are all within the normal range; Load to rated load and run for 1 hour, monitor temperature rise changes to ensure no abnormalities.
In daily prevention, it is necessary to establish a regular maintenance mechanism: check the status of the cooling system (fans, water pipes, water pumps) every week, measure the insulation resistance and bearing temperature of the motor winding every month, replace the bearing grease every quarter, and reduce the occurrence of high temperature rise faults from the source.
Through the closed-loop process of "emergency investigation repair prevention", the problem of high temperature rise in high-speed motors can be effectively solved, the service life of motors can be extended, and the overall stability of equipment operation can be guaranteed.