Cost ranges by generator size
| Generator size | Stator rewind | Full rewind (stator + exciter) | Emergency surcharge |
|---|---|---|---|
| 5 to 25 KW portable / small | $1,500 to $2,800 | $2,500 to $4,000 | +25 to 40% |
| 25 to 75 KW commercial | $2,500 to $5,000 | $4,000 to $7,000 | +25 to 40% |
| 75 to 150 KW commercial | $4,500 to $7,500 | $6,000 to $10,000 | +25 to 50% |
| 150 to 500 KW industrial | $7,000 to $15,000 | Quote individually | +25 to 50% |
| 500 KW+ large alternator | Quote individually | Quote individually | Negotiated |
Ranges are for US shops at standard turnaround. AC synchronous generator stators. DC generator armature rewinding priced separately, submit your details for a quote.
What affects generator rewinding cost
- Winding scope
- Stator-only rewinds are the most common and least expensive. If the exciter or rotor also needs rewinding, add 40 to 80% to the stator cost.
- Voltage class
- Generators above 600V require form-wound coils, specialized insulation, and elevated hi-pot testing, significantly more than random-wound low-voltage stators.
- Manufacturer and parts availability
- Common brands (Kohler, Generac, Stamford, Leroy Somer, Marathon) have established rewind specs. Obscure brands may need reverse-engineering before work begins.
- Urgency
- Critical backup units (hospitals, data centers, utilities) often command a 25 to 50% premium for priority scheduling and overtime.
How generator rewinding differs from motor rewinding
Not all motor repair shops do generator rewinding. The key differences:
- Output voltage testing. Generators must be tested at rated output voltage and frequency, often with a load bank, not just a no-load spin.
- Exciter and AVR expertise. AC synchronous generators have an exciter and AVR. Missing related faults can cause early repeat failure.
- Winding configuration. Generator stator coil pitch, slot fill, and leads differ from typical motor stators.
When submitting your request, specify that your unit is a generator (not a motor) so we match you to shops with confirmed generator rewind capability.
Get a generator rewind quote
Submit KW rating, manufacturer, failure symptoms, and urgency, matched to shops with generator rewind capability in your area.
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Frequently asked questions
- How much does it cost to rewind a generator?
- Generator rewinding typically costs $1,500 to $15,000 depending on the generator's KW rating, winding configuration (stator only, rotor/armature, exciter), and whether emergency turnaround is needed. Small portable generators (5 to 25 KW) run $1,500 to $4,000. Medium commercial generators (25 to 150 KW) run $3,000 to $8,000. Large industrial generators above 150 KW are quoted individually and can exceed $15,000 for large alternators.
- What parts of a generator can be rewound?
- The stator (main winding), rotor or armature (on DC generators and some AC brushed types), and exciter winding can all be rewound. Most generator failures involve the stator winding due to insulation breakdown from heat, moisture, or voltage surges. Exciter failures are less common but require specialist capability.
- Is it worth rewinding a generator or should I replace it?
- For generators above 25 KW, rewinding is almost always worth it, replacement costs and lead times for industrial generators far exceed the rewind cost. For small portable generators under 10 KW, replacement is often cheaper. For standby generators in critical applications, rewinding with a full test protocol provides a documented known condition that replacement with a used unit cannot.
- How long does generator rewinding take?
- Standard generator rewinds take 7 to 14 business days depending on size and parts availability. Large alternator rewinds requiring custom coils take 3 to 6 weeks. Emergency rewinds are available at many shops for smaller generators, turnaround of 3 to 5 days at a premium rate.
- What testing is done after generator rewinding?
- A proper generator rewind includes insulation resistance (megohm) testing, winding resistance measurement, high-potential (hi-pot) testing per IEEE standards, and a no-load run test at rated voltage and frequency. Output voltage regulation and waveform quality are verified before return. Request a written test report, professional shops provide this as standard.