According to our company's experience in ABB motor maintenance of the Cambodia Hydropower Eight Bureau Hydropower Station

The main point of daily maintenance inspection of the motor is to find out the abnormal state of the equipment early and handle it in time to prevent the accident from expanding. The maintenance personnel can find abnormal phenomena according to the action and signal of the relay protection device, and can also rely on the experience of the maintenance personnel to judge the accident.

1, the first is the visual inspection

By visually, the following anomalies can be found: whether the external fasteners of the motor are loose, whether the parts are damaged, whether the surface of the equipment is oily or corroded, whether there are discoloration, burn marks and smoke marks at the contact points and joints of the motor. phenomenon. The reason for these phenomena is due to local overheating of the motor, poor conductor contact or burnt of the windings; If the voltmeter is not indicated or is abnormal, it indicates that the power supply voltage is unbalanced, the fuse is blown, the three-phase resistance of the rotor is unbalanced, single-phase operation, and poor conductor contact. If the ammeter indication is too large, it indicates motor overload, bearing fault, winding turn-to-turn short circuit, etc.; motor stalls, caused by: power failure, single-phase operation, low voltage, too small motor torque, excessive load, voltage Falling too large, bearing burned, mechanically stuck, etc.

2, using the auscultation stick to hear the various noises of the motor by hearing

These include electromagnetic noise, ventilation noise, mechanical friction sound, bearing noise, etc., so that the cause of the motor failure can be judged. The causes of noise are mechanical: bearing failure, mechanical imbalance, loosening of the fastening screw, non-conformity of the coupling connection, rubbing of the stator core, etc.; electrical: voltage imbalance, single-phase operation, winding There are open circuit or breakdown failures, poor starting performance, and poor acceleration performance.

3, by smell, you can find burnt smell, smell

The causes of this phenomenon are: motor overheating, winding burnout, single phase operation, winding failure, bearing failure, etc.

4, by touching the surface of the casing by hand, you can find the temperature of the motor is too high and the vibration phenomenon

The causes of vibration are: unbalanced mechanical load, looseness of various fastening components, insufficient strength of the motor base, improper coupling of the coupling, uneven air gap or mixed debris, voltage imbalance, single-phase operation, winding failure, Bearing failure, etc.

The cause of excessive motor temperature is overload, cooling air duct blockage, single-phase operation, turn-to-turn short circuit, high or low voltage, three-phase voltage imbalance, poor acceleration characteristics, long starting time, stator and rotor phases. Bad contact of the wiper, starter, frequent start and brake or reverse brake, excessive inlet air temperature, mechanical jam, etc.

When the temperature of the motor is estimated by hand to estimate the temperature, since each person's feeling is different and subjective, it is determined by experience.

Routine maintenance inspections are divided into daily inspections, monthly or periodic inspections, and annual inspections.

In the daily inspection, the main inspection of the lubrication system, appearance, temperature, noise, vibration and abnormal phenomena, but also check the ventilation cooling system, sliding friction conditions and the fastening of various components, and carefully check the records.

During monthly or regular inspections, check whether the switch, wiring, grounding device, etc. are loose or not, and if there are any damaged parts, if there are plans and repair measures, check the dust accumulation, clean them in time, check the lead wires and match Whether the line has damage and aging problems. Test the insulation resistance of the motor windings and record.

In addition to the above items, the annual inspection contents should also be disassembled to perform the core check, clean or clean the grease, and check the insulation.

Three-phase asynchronous motor small, medium and large repair project

1, minor repair project

(1) The motor is blown clean and a general inspection is performed.

(2) Clean the bearings, check and change the oil.

(3) Dealing with local insulation faults of the windings, performing winding binding reinforcement and wrapping lead insulation.

(4) Tighten all the screws.

(5) Adjust the fan and fan cover and reinforce them.

2. Medium repair project

(1) Contains all minor repair items.

(2) Clean and clean the motor, replace the local coil and repair the insulation of the reinforced winding.

(3) Motor disassembly inspection, handling loose coils and wedges, and fastening parts for each part.

(4) The rotor is subjected to dynamic balance test.

3. Overhaul project

(1) Contains all the contents of the intermediate repair project.

(2) The windings are all rewinded and updated.

For the phenomenon of your current motor, it is because the method is wrong when refueling, which leads to a large amount of oil inside the windings. If it is not treated in time, it will have a great impact on the safe operation and service life of the motor. Due to the accumulation of grease, it will affect the heat dissipation of the motor windings and increase the operating temperature of the motor. Grease will also slowly corrode the windings, reducing the insulation performance of the motor windings. As the temperature of the motor winding increases, the internal and external temperatures of the motor rise, which also affects the operating environment of the bearing.

During the use of the motor, the corresponding maintenance and maintenance is very necessary. I hope that your company will pay attention to it. The corresponding treatment method is: disengage the coupling, the cooling fan, open the front and rear end caps of the motor, clean the grease on the front and rear windings of the motor, clean the winding with toluene, and clean the winding and end cap of the motor. After cleaning, it should be aired for one to two hours. After the toluene is evaporated, the motor can be installed. Finally, the coupling is assembled and the test run is started.

The daily maintenance of the bearings of the motor should be carried out in strict accordance with the requirements of the "ABB Motor Instruction Manual".

No maintenance grease failure, resulting in bearing burnt

Stator terminal block overcurrent burned

If the motor stress is too large, the shaft end load is too heavy, resulting in a short shaft. The belt is too tightly adjusted and the tension is too large.

Broken crack presents spiral, excessive stress, metal fatigue

The open-air motor bearing is damp, causing the grease to oxidize, and the shaft has rust spots and makes a sound.