Motor maintenance skills

 Motor maintenance skills

The motor maintenance skills include the following aspects:

Visual inspection method:

Observe whether there is any leakage, bulging or bursting phenomenon in the electric motor, whether there is any fracture, wear, detachment, misalignment or looseness in the mechanical components, whether the wire joints are in good condition, whether there is a lot of dust, whether the connections are correct, whether the joints are disconnected, and whether the electric motor ignites or smokes when powered on.

Listen: Listen with your ears to see if there are any abnormal sounds from the motor during operation, such as a uniform and continuous slight buzzing sound from the rolling bearings, a smaller sound from the sliding bearings, and no noise. If there is an abnormal sound, it may be due to the rupture of the bearing steel ring, scars on the ball bearings, impurities such as sand mixed in the bearing, or mild wear on the bearing parts.

Touch: Use your hand to check if the screws of the motor are loose and if the casing is overheated. If the casing is found to be overheated, cut off the power supply.

Smell: When powered on, use your nose to smell the electric motor for any burnt smell. The burnt smell inside the motor is mainly caused by the burnt terminals or windings of the motor.

Dismantling inspection:

Before disassembling, understand the basic data of the motor, check the condition of the motor, understand the winding principle, voltage, current, power, wiring method, number of poles, and speed of the motor. Use a multimeter to check whether the winding resistance value is within the normal range and whether the ground resistance is qualified.

When disassembling, make a record of the installation sequence and position of each component. Determine the cause of the burnt out winding based on the condition. Before disassembling, record the wiring method of the junction box, the installation position of the outer shell, and make marks.

Winding maintenance:

When dismantling a winding, it is necessary to record the wiring method, lead out position, insulation condition, number of slots, number of coil poles, wire diameter model, number of turns, span of each turn, stator core length, and inner diameter size of the winding.

When embedding the winding wire, determine whether to use a single or multiple seven wrapped wires according to the wire diameter model. The sum of cross-sectional areas must be consistent with or very close to the original wire model. The length of the wire mold should be appropriate. Cut the insulation paper, wind the wire, and lay it down. Be careful not to damage the insulation paint on the surface of the enameled wire.

Wiring should be done according to the method recorded during disassembly. The joints need to be welded and insulated with insulating sleeves. When installing and tying the wires, attention should be paid to ensuring that the rotor does not touch the coil during installation.

Soak the insulation paint, dry it, and after binding the winding coils, first use a megohmmeter to measure the insulation resistance to ensure that there is no problem with the insulation. Then pour the insulation paint and dry it in the oven.

Bearing maintenance:

When the temperature of the rolling bearings of the electric motor exceeds 95 ℃ and the temperature of the sliding bearings exceeds 80 ℃, it is considered that the bearings are overheated. The reasons and countermeasures include bearing damage that needs to be replaced, insufficient or excessive lubricating grease for rolling bearings, or impurities such as iron filings. The capacity of the lubricating grease should not exceed 70% of the capacity of the bearing and bearing cover. If there are impurities, it should be replaced, and the fit between the bearing and the end cover should be too tight or too loose.

Fault diagnosis and handling:

Classify and handle motor faults based on their type, severity, and complexity of maintenance methods. First, eliminate simple problems that are easy to troubleshoot, such as poor contact and insufficient power input.

For faults such as internal open circuit, output short circuit, and bearing wear in the motor, different treatment methods need to be taken, such as replacing the motor, replacing the carbon brush, and cleaning carbon deposits.

Safety precautions:

During the process of motor maintenance, special attention should be paid to safety issues. For example, when disassembling the motor, the power should be cut off first to ensure the safety of personnel and equipment.

By using the above techniques, motor maintenance can be effectively carried out to ensure the normal operation and service life of the motor.