Rewinding an electric motor takes training, skill and it is a bit of an art. Rocky Mount Electric Motor is very proud of our winding technicians. Our electric motor maintenance team has years of experience that you can trust and undergo continual education to stay on top of latest trends. And, we like to share that experience with our customers so they know exactly what to expect when they ask us to rewind an electric motor.
The Process to Rewind an Electric Motor
The steps to rewind an electric motor may seem simple, but we would like to remind our customers of the process to help our customers better understand the work that Rocky Mount Electric Motor performs on your equipment and to better understand the time required to rewind a motor. The time naturally will vary with the size of the motor.
1. Record Winding Data
The first step is to record the winding data. As described in the ANSI/EASA AR100 Standard for Recommended Practices for the repair of rotating electrical apparatus, it states that, “The winding should maintain the same electrical characteristics as the original. Winding data should be reviewed for accuracy.”
2. Removing Old Coils
We first need to remove the old coils within the motor. To accomplish this, the stator is put into a burnoff oven. The temperature in the oven has to be maintained not to exceed 700°F and a chart recorder is used to record the temperature. This is done to be sure not to degrade the interlaminar insulation or cause distortion of any part. This process takes 8 hours.
3. Stripping of Windings
Then, the windings have to be removed from the motor. After windings are removed, the core slots are inspected to ensure they are free of sharp edges and foreign material. Then the inside of the stator is painted with anti-tracking paint.
4. Insulating the Stator
Having removed the old coils, we then need to cut new insulation that will go inside the motor. We carefully cut insulation paper into uniform pieces, then push them into the clean slots of the stator.
5. Creating new coils
To make the process of creating new coils simpler, we create a test coil from a piece of wire that we can use as a guide for the necessary length for creating the coils. We apply this size to our winding machine to ensure uniform coils. Once the first coil completes, we use this as a first sample to ensure our measurement is correct and it is the right size for the motor. Ensuring the proper size means the motor operates correctly, so we carefully check this on every rewinding project. Once we check and confirm we have the correct size, we then create the rest of the new coils.
6. Coil Assembly
We then insert each of the new coils into the motor, evenly spacing them apart from one another. After they are in place, we insulate the ends of the wires before connecting them at a later stage. We then wedge epoxy glass into each of the coil slots to keep everything firmly held in place. This completes the first stage of rewinding, with each separate coil group ready for phase installation! Depending on the size of the motor, this process takes hours.
7. Insulation of Phases
On larger motors we then insulate each separate phase with insulation paper. Without it, any contact between them can lead to a shortage. So, we have to make sure that we carefully insulate each one properly. Then, we tie together the wiring and insulation paper for a tight grip. After, the insulated wire ends from the previous step are trimmed to length for connecting to the start and end of the phases. They are then wound in the same way that the original wiring was. Wiring patterns are important to get right. This is the most critical part of the process and why it’s important to leave the overall process of rewinding a motor to a professional team like Rocky Mount Electric Motor.
8. Preparing Wire Ends
Once wound together, the wire ends are then soldered together. After soldering, we then insulate the ends as well, cutting the insulation to the proper length. Then the wire ends are laced to the rest of the system, keeping things clean and uncluttered. Then the start and end phase wires are pulled through the terminal box.
9. Careful Testing
With everything put together, we then put the wiring through some careful testing. We test wiring to make sure everything has been properly insulated. Then, we discharge anything that may have built up in them. Next, we check the system with measuring equipment to ensure there are no open circuits.
10. Finishing Touches
After testing, if the motor needs a new layer of paint at the end, we submerge the motor in varnish, then bake it at specific temperatures to set the varnish on the whole piece of equipment. This process can take up to 8 hours. We then test wires once again to ensure the circuits are properly working. After this, we place new bearings on the rotor and place it back into place within the stator. We also re-insert the drive end cover.
After everything has been put back into place, we then test the motor to make sure everything works as intended. Depending on what the motor attaches to, all other parts are then reattached, with smaller components replaced as necessary. This includes parts like pump ends, cooling fans, the terminal box cover, and more. Then, the whole system gets a new paint job to further protect it.
As you can see this is an involved and careful process that takes many hours to complete correctly. If you have an emergency situation we call “Rush Jobs”, we work overtime to get your motor back to you as soon as possible.
Trust Us to Rewind an Electric Motor
Rocky Mount Electric Motor works on electric motors of all sizes for any industry. Our extensive knowledge of electric motors and their working components helps to diagnose and repair your motor, and this includes rewinds. Rocky Mount Electric Motor is an EASA Accredited repair shop, so you know your motor will be repaired following stringent industry guidelines. Reach out and give us a call today to learn more, or reach out on our contact page! We’ll happily help get your motor back running even better than new.
Also ask us about predictive maintenance services to “Keep your motor running.”