When an industrial motor fails, you have two basic choices: revise the existing motor or buy new. For powers above 22 kW the revision is often cheaper and much faster. This guide gives a decision tree and a concrete 55 kW cost comparison so you can make the right call.
The decision tree in 5 questions
Five questions determine whether revision or new is the right path:
- 1. Is the motor less than 20 years old AND in standard IEC format? If yes, revision is usually possible.
- 2. Is the winding intact (no burn-through)? If yes, revision time: 1-2 weeks. If no: 3-6 weeks (rewinding).
- 3. Is the motor above 22 kW? Revision becomes more cost-effective above this threshold.
- 4. Do you need the motor within 3 months? New motor lead time is minimum 3 months, typically 12-16 weeks, revision is almost always faster.
- 5. Do you have class/ATEX certification requirements? Revision with new test protocols can be certified; new motor needs full documentation chain.
55 kW case study: revision vs new
A typical 55 kW IEC frame 250 motor with bearing damage and intact winding. New ABB M3BP IE3 list price approximately €4,500, lead time 2-4 weeks (or directly from stock). New Dormot Pro approximately €2,800. A Dormot Renew 55 kW (revised as new) is €2,300 from stock.
Revision cost: typical €2,500 without rewinding (strip and inspect, new SKF bearings and seals, test protocol and documentation, output certificate). With rewinding add €2,000-2,500 (€4,500-5,000 total). Marine conversion if applicable adds another €800. Lead time: 1-2 weeks (without rewinding), 4-6 weeks (with rewind).
Comparison: revision without rewinding (€2,500) saves €2,000 versus a new ABB and is 10+ weeks faster. Versus a new Dormot Pro (€2,800) the savings are minimal, buying new often makes more sense. With rewinding, revision typically costs more than a new Dormot. For a ship stranded in port at €15,000/day downtime cost, speed alone often justifies revision regardless.
What's in our revision
Dormot Renew is our revision programme. Every motor goes through: complete stripping, visual inspection, winding test (insulation resistance, DC high-voltage, tan delta), bearing replacement with new SKF/FAG bearings, new seals, rebalancing, marine-grade coating if required, final running test with measured parameters (current, power factor, vibration, temperature rise).
You receive a detailed test report showing measurable differences: before/after insulation resistance, vibration spectra, temperature rise at rated load. This is not a "quick repair", it's a full restoration to as-new specification. Class societies accept our revision for non-essential duty across all 6 major societies
When to buy new
Despite revision being often attractive, some cases favour new: motor older than 25 years (class society may refuse), efficiency upgrade from IE2 to IE4/IE5 as part of replacement, specialty applications (ATEX Zone 1 with outdated design, submersible motors), power above 1500 kW where rewinding is impractical.
We are happy to advise, no commitment. Provide the motor data (type, serial number, power, voltage, current failure mode, required delivery date) and we return a recommendation and quote within 48 hours covering both paths.
Frequently asked questions
How long does motor revision take?
Typically 1-2 weeks if winding is intact, 4-6 weeks if rewinding is required. For motors above 500 kW full revision can take 6-8 weeks. Always much faster than a new motor (minimum 3 months).
Is revision as reliable as new?
Yes,Yes, for a properly executed revision. Our test protocols measure insulation, vibration, temperature rise and running parameters against as-new specifications. Where winding is new (rewind) the motor is functionally comparable to new. No rights can be derived from this indicative guidance, actual results depend on motor condition.
Can revision meet ATEX certification?
Revision can meet ATEX requirements if the original certification is still valid and the revision work does not change the fundamental construction. Certain work (e.g., flame path machining) voids ATEX, discuss before starting.
Need advice on motor selection?
Our sales engineers are happy to help you find the right motor for your application.