Maintenance and repairs are a necessity that are required for all motors, but it is particularly important if you want to increase their lifespan.
The AC induction motors are very useful and powerful tools. They are versatile enough to serve as AC motor speed controllers for braking systems & even to provide electricity to complete houses. On the other end, if they are not well cared for, they won’t be of much service. However, taken a number of precautions and continue to monitor the situation on a daily basis, it do not need to be concerned.
Maintain analysing to learn about critical maintenance checklists that should be followed, to maintain an electric motor in good condition.
The following are the two categories which come under maintenance:
1). Restorative Maintenance
2). Protective Maintenance
Restorative Maintenance
It is the most fundamental type of maintenance and repair. There are several drawbacks associated with restorative maintenance, some of which include a decreased amount of time for the machine’s usable life and the loss of important energy. In certain circles, it is also referred to as Corrective maintenance.
Preventive Maintenance
The practise of doing preventive maintenance is known as protective maintenance.
It is the practise of doing routine inspections on the motor on a weekly, monthly and yearly basis in order to ensure that everything is in working order and to identify any problems at an earlier stage.
Some examples of preventative maintenance include tightening the belt, adjusting the tension of the belt, replacing the filters, and changing the oil.
It is important to not wait for anything to fail (or) break before looking into the issue, and this applies whether the motor in consideration is a DC motor or an AC motor.
Safety Precautions of Induction Motor
Safety precautions include the following:
- Visually inspect the motor, pulleys, belts, and machine to be powered for any hazards,
- Listen for odd noises, such as tapping or humming,
- Experience the motor housing to ensure it hasn’t overheated, and
- Visually check to ensure the motor isn’t vibrating excessively.
Overload Protection of Induction Motor
Overload occurs on induction motors by:
- Belts that are overly tight,
- Improper lubrication,
- Worn pulleys, and
- Overloads that cause clogging are examples of improper installation.
Other examples include
- Improper wiring and
- Inadequate voltage.
- Foreign objects being introduced into motor
Overload protection will ensure that the motor circuit has the appropriate fuses installed. Generally overload protection that is built into the motor control through a manual reset switch and starter for the motor that is unique (current-limiting starter).
Vibration levels kept to a minimum. Proper alignment to be checked since misalignment contributes to premature belt & bearing wear and it will serves an element in the overloading of the motor.
Protect against Excessive Oiling
An excessive amount of oil might result in an accumulation of more dust and the damage of the insulation inside the motor.
Dust Accumulate Prevention
Dust accumulation in and on a motor works as insulation & may cause excessive heating of the motor.
Moisture Protection
Since moisture conducts electricity, a wet motor must be properly dried before operation.
Bearing Maintenance
Rolling bearings greased are typically used in motors. Apart from close-type ball bearings, all other bearings are open type to minimise over-greasing by permitting grease injection and outflow.
Inspecting the bearings is more important. Bearing failures are often the consequence of improper lubrication, machine load, or faulty installation. Cleaning the grease from the ball (or) bearings, as well as removing and replacing the grease ball or roller bearings, are critical maintenance.
These do not include regular procedures to do on a weekly basis, but they are necessary every six months. In addition to examining the bearings, one should:
- Clean the motor thoroughly.
- Brushes that are over fifty percent worn should be replaced.
- Brush holders should be cleaned.
- Check and tighten connections.
Additionally, these are not routine tasks of maintenance that must be completed on a weekly basis. If identify any difficulties in the above areas during weekly inspections, correct them right immediately, but every six-month period should satisfactory.
Periodical Maintenance
1).Weekly Maintenance
The weekly maintenance schedule is as follows:
- Examine the commutator and the brushes.
- Examine the starting switch, fuses, & other controls for wear and tear, and tighten any loose connections.
- Check to see whether the machine reached its rated speed in a reasonable amount of time.
- Check the oil level in the bearings.
2). Monthly Maintenance
The maintenance schedule for every 6 months is as follows:
- Clean the motor completely, blowing dirt out of the windings and wiping the commutator and brushes.
- Replace any brushes that are more than half worn.
- Examine brush holders and, if necessary, clean them. Make sure the brushes are free to move about in the holders.
- Drain, clean, and refill the oil in the sleeve bearings.
- Inspect the oil in ball and roller bearings.
- Check that all covers, belt & gear guards are in excellent working condition and properly attached.
- Inspect and tighten motor and control connections.
3). Yearly Maintenance
The maintenance schedule for every year is as follows:
- Clean and re-grease ball and roller bearing housings.
- Remove any magnetic dirt that has clung to the poles.
- Check the space between the shaft & journal boxes of sleeve bearing motors to avoid running with worn bearings.
- Clean out the commutator’s undercut slots. Examine the smoothness of the commutator.
- Inspect the connections between the commutator & armature coils.
- Megohmmeter is used to test insulation.
- Examine the air gap.
