Signs your permanent magnet motor needs rewinding
- The motor runs hotter than usual under normal load.
- There is a drop in efficiency, meaning it draws more current for the same output.
- You notice a burning smell or visible discolouration on the windings.
- The motor's torque output feels weaker than when it was new.
- There is unusual noise or vibration during operation.
- The motor trips protection devices more frequently than before.
Because permanent magnet motors rely on the rotor's magnets as well as the stator windings, it is worth having both checked together, since a rewind will not fix a demagnetised rotor.
How a permanent magnet motor works and why the windings fail
A permanent magnet motor uses fixed magnets mounted on the rotor instead of an electromagnetic rotor field, which means the stator windings only need to create a field that interacts with the rotor's existing magnetism to produce rotation. This design tends to be more efficient than motors that need to generate a rotor field electrically, since less energy is spent maintaining the rotor's magnetic field.
Winding failure in permanent magnet motors usually comes down to the same core causes as other motor types, insulation breakdown from sustained heat, contamination in the operating environment, or mechanical stress on the winding connections over time. One additional consideration with permanent magnet motors is that running the motor well beyond its rated temperature can also begin to weaken the rotor's magnets, which is a separate problem from the windings and will not be resolved by rewinding alone.
What rewinding a permanent magnet motor actually involves
The stator is removed and its existing windings are stripped, then the core is checked for lamination damage before proceeding. New wire is wound to the original manufacturer specification, matching turns count and wire gauge to preserve the motor's rated torque and speed characteristics.
The stator is then insulated and the windings are dipped or impregnated with varnish, followed by curing to lock everything in place. As part of the process we also check the rotor's magnet strength, since a rewind paired with a demagnetised rotor will still leave the motor underperforming. If the magnets have weakened significantly, we will discuss the options with you before completing the job.
Once reassembled, the motor is run tested to confirm current draw, torque, and temperature are within expected range.
Our rewinding and repair process
- Initial inspection of windings and rotor magnet condition.
- Full strip down and testing of the stator core.
- Rewinding to the original manufacturer specification.
- Insulation testing and varnish curing.
- Reassembly and full load testing before dispatch.
- Delivery or pickup coordination to suit your schedule.
Frequently Asked
Questions
Can rewinding fix a permanent magnet motor that has lost torque?
Only if the cause is winding related. If the rotor magnets have weakened from heat or age, rewinding the stator alone will not restore full torque, and we will let you know if this is the case.
Do you check the rotor magnets during inspection?
Yes, we assess magnet condition as part of every permanent magnet motor inspection, since this affects whether a rewind will actually solve the performance issue.
How long does a permanent magnet motor rewind take?
Turnaround depends on motor size and complexity. Contact us for a current estimate based on your specific motor.
Is a permanent magnet motor more expensive to rewind than a standard motor?
Cost depends on motor size and winding complexity rather than motor type alone. Contact us for a quote specific to your motor.
Your Local Auckland Based Motor Rewinder
When rewinding an electric motor, it is important to find a reliable service provider in order to ensure proper maintenance and repair of the equipment. A reliable service provider will have experience in the field, offering quality workmanship and specialized services.
They should also be licensed and certified, so customers have the assurance that they are dealing with a professional who meets industry standards. Finding a reliable service provider can help prevent damage or loss of equipment, saving time and money in the long run.
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