Motor Rewinding Training
Technical Assistant, Department of Electrical and Electronics Engineering Industry, National Training and Productivity Centre, Fiji National University National Training and Productivity Centre, Fiji National University.
What is motor rewinding? Electric motors, or industrial motors as most started referring to them, are a part of our daily life.
Our computers, air conditioners, refrigerators, and many other products use industrial motors to transform electrical energy into mechanical energy.
In addition to being a part of our daily life, industrial motors play a significant role in many industrial operations.
In factories, a wide range of goods are created, and almost all of them eventually require the use of an industrial motor.
Low insulation resistance is a problem that develops over a motor’s lifespan and is brought on by pollution, vibration, and power surges.
Rewinding an electric motor can increase insulating resistance
while also increasing the motor’s efficiency.
Preserving the stator core’s electrical integrity is the most crucial part of the rewind process.
In addition to increasing core loss, insulation degradation can also raise the temperature of the motor, which may lead to the motor failing early.
Here at National Training and Productivity Centre, the Department of Electrical provides specialised courses to train students in fields of maintenance planning and later on motor rewinding.
These training enables the participants to successfully repair and rewind motors which is a more effective method to rejuvenate the dead motors.
This training is both for single and three phase AC motors.
The following fundamental procedures are involved in rewinding an electric motor will be part of the trainee practical tasks in our motor rewinding module for single and three phase motors:
Burnt winding connection and data record
Stripping and cleaning of burnt motor stator
Rewinding of new coils Placement or insertion of new coils
Connection of new coils Binding of new coils
Testing of new coils
Vanishing of new coils.
Why each winding very important:
procedures is
Even though motors have the same horsepower, speed, and voltage, their windings typically differ significantly, thus a technician will need to collect winding data. Included in this information are the quantity of slots, wire size, coils, turns per coil, essential dimensions, bracing, and insulation characteristics.
The original motor is replicated using this information, and it is also used to suggest design changes that could enhance performance and increase the mean time before failure.
The current motor windings are taken out of the motor core once all the important data has been acquired.
The process begins by placing the motor’s stator in a high-temperature furnace known as a burnout or burn off oven.
To prevent the motor from overheating and damaging the core insulation, you must ensure that the oven is recording both part and oven temperatures.
A water suppression system ought to be included in the oven as well to prevent the heat from rising too high.
The insulation is practically burned to ash during this burnout stage, which can take several days for bigger units.
After it has cooled, the windings are physically removed from the stator core, a process known as stripping.
The majority of the time, winding data is gathered both before and after stripping.
To check the integrity of the core iron insulation, a core-loss test should be done both before and after the oven operation.
The actual creation of the coils comes next.
Placement, wire tension, and taking note of the coils number of turns are important aspects of this procedure.
The coils are made, placed in the slots of the stator, and then connected.
The procedure for inserting coils differs depending on whether you are orking on a form coil winding
or a random wrapped winding, but the fundamental steps involve placing coils and insulation into the motor core.
The coils must then be joined to create the whole winding.
A crucial point to keep in mind during this procedure is the blocking and bracing of the winding. A winding might fail due to mechanical movement if it is not adequately braced.
The integrity and caliber of the coil windings are tested repeatedly during the whole rewinding procedure. varnish dip, often known as varnishing or dip and bake, is a process that involves preheating the new wires, dipping it in a pool of varnish (which might be waterbased or epoxy-based), and then baking it in a furnace to thoroughly cure the varnish or resin.
After a rewind is finished, repair shops often proceed in this manner.
Employment opportunities:
Over the past 20 years, most of our electrical trainees have used the skills and knowledge leant from
this training programme to start their own private motor rewinding business locally or have joined the big electrical companies doing motor rewinding.
Fiji at present are in shortage of good competent motor reminders, so do not miss this training opportunity and get yourself enrolled! NTPC is the only technical training provider in Fiji who can transform you to be a competent and reliable motor winder.
For more information or queries on NTPC short courses, email info. ntpc@fnu.ac.fj
Disclaimer: The views expressed in this article are of the author and do not In Any wAy rEflECt or rEprEsEnt the position of the Fiji National University.