Electric motors power nearly every industrial facility. When one fails, downtime and lost productivity can cost thousands of dollars per hour. That’s why choosing the right approach to electric motor repair and maintenance is critical.
Business owners and plant managers typically have two options:
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In-house motor repair and service (if staff and equipment allow).
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Partnering with a reputable electric motor repair shop accredited by industry standards such as EASA AR100.
This guide from KnowerNetwork.com walks you through the motor repair process, inspection steps, rewinding, and testing so you can make informed decisions about extending the life of your motors.
Why Electric Motor Service Matters
Regular electric motor maintenance helps prevent failures, reduces repair costs, and maximizes motor efficiency. The U.S. Department of Energy’s Office of Industrial Technologies (OIT) and EASA (Electrical Apparatus Service Association) have published guidelines to ensure motors are serviced properly.
When selecting a service provider, always verify that the shop follows EASA AR100 standards, which outline best practices for inspection, testing, and rewinding.
Step 1: Motor Inspection
A proper motor inspection identifies early signs of damage and determines the repair scope.
Key inspection steps include:
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Visual check for broken components, cracks, and contamination.
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Winding integrity tests for insulation resistance.
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Shaft rotation check for binding, warpage, or bearing wear.
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No-load test at full voltage to measure vibration and current draw.
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Resistance measurements to document winding condition.
Step 2: Dismantling the Motor
Once inspected, the motor is carefully disassembled:
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Bearings are checked for wear or thrust damage.
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Electrical connections are cleaned and tested.
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A core-loss test identifies electrical losses within the stator core.
Step 3: Preparing the Core
A core flux test reveals structural or insulation issues. Common defects include:
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Core waviness or cracks
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Loose vent fingers
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Lamination displacement
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Groove or wedge damage
If core losses exceed OEM specifications, the stator core may need grinding, re-insulation, or full replacement before rewinding.
Step 4: Diagnosing Winding Failures
Winding failures are among the most common motor problems. Causes include:
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Turn-to-turn shorts
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Coil-to-coil or coil-to-ground faults
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Phase-to-phase breakdown
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Open circuits
Technicians look for overheating, moisture damage, foreign debris, or insulation deterioration to determine the true cause of failure.
Step 5: Rewinding the Motor
Once diagnosed, damaged windings are removed:
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Motors are placed in a burn-out oven (max 650°F) to loosen varnish.
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Stators are cooled, stripped, and prepped for new windings.
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New coils are wound using magnet wire with enamel insulation, then taped and reinforced to OEM specifications.
Step 6: Bearings and Precision Parts
Motor bearings are precision-engineered and often fail due to:
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Lack of lubrication
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Improper installation
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Excessive wear
Replacing or reconditioning bearings ensures smooth operation and longer motor life.
Step 7: Reassembly and Final Testing
After rewinding and bearing replacement, the motor is reassembled and tested:
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No-load test run verifies balanced current and acceptable vibration levels.
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Final electrical testing ensures compliance with EASA AR100 and manufacturer specs.
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Motors are painted, documented, and prepared for shipment.
Choosing the Right Electric Motor Repair Shop
Not every shop follows industry best practices. When selecting a service partner:
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Verify EASA accreditation.
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Ask for documented test results.
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Confirm that repairs follow DOE and manufacturer guidelines.
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Request maintenance records for warranty protection.
Final Thoughts
Your electric motors are vital assets. Whether you perform service in-house or outsource to a trusted repair center, following a structured inspection, testing, rewinding, and reassembly process ensures maximum reliability and return on investment.
At KnowerNetwork.com, we provide actionable resources to help you maintain, repair, and optimize electric motors. By choosing the right repair partner and adopting a proactive maintenance strategy, you’ll keep production moving—and avoid the costly impact of motor failure.
