An electric motor on your production line has burned out and you face the classic decision: should I have it rewound, or buy a new one? At first glance this question looks like "which is cheaper", but the right answer cannot be given by looking at the invoice alone. The post-rewind efficiency loss, the absence of warranty, the delivery time and the motor's frame size change the decision completely. In this article, from the perspective of a business owner making a purchasing decision, we explain with clear criteria when rewinding makes sense and when buying a new motor from stock makes sense.

As HEM Motor, we have manufactured electric motors since 1979 and, with our strong stock in Turkiye, we can ship most standard powers on the same day. Our goal in this article is not to push you to one side; it is to help you make the right electric motor decision with data. In some cases rewinding really does make sense; in others, a new motor is both faster and, in the long run, more economical.

To make this decision correctly, you need to look at four axes: the motor's frame size (its physical size and therefore the relative value of a new motor), whether the rewind can preserve the efficiency class, your warranty and assurance needs, and how long the line can stay down. In this article we address these four axes one by one and, at the end, give a practical decision summary. This way, before going to the rewinding shop, you will have clarified which direction to lean. We do not give a specific monetary figure because every motor, brand and environment is different; but the decision logic is the same in every case.

Comparison of rewinding a burned electric motor versus a new asynchronous motor

The First Criterion That Determines the Decision: Frame Size

There is a common and justified rule in the industry: for small-frame motors (roughly frame 100 and below), rewinding is usually not sensible. Because in these motors the rewinding labor and material approach the value of a new motor; on top of that you get no warranty, you experience efficiency loss, and you also wait out the delivery time. For motors below frame 100, the wise choice is to replace them directly with a new motor from stock.

For high-power, large-frame motors (for example frame 132 and above, high kW), the picture changes. In these motors, if the frame, shaft and cast parts are sound, a quality rewind can be more economical than a new motor. Even here, though, the critical question is whether the rewind preserves the efficiency class. Because high-power motors generally run continuously and at high load; this means even a small efficiency loss creates a big difference in the annual bill. So although rewinding is more often sensible in a large frame, the "is efficiency preserved" question is decisive here too.

How do you determine the frame size? The number written on the motor nameplate or on the frame (for example 80, 90, 100, 112, 132) indicates the frame size. This number expresses the shaft center height of the motor in millimeters. The shaft of a frame-90 motor is 90 mm above the base. As the frame size grows, the motor physically grows, contains more copper and heavier casting; so the rewinding labor increases but the relative value of a new motor also changes. That is why the "new below frame 100, rewind above depending on condition" rule is a good starting point in practice. To see frame size and power matching in more detail, our article on frame size and power matching will be useful.

The Hidden Items of Rewinding Cost

When making the rewind decision, looking only at the rewinding fee is misleading. The total cost also includes the following:

  • Labor and disassembly-assembly: Disassembling the motor, cleaning the old winding, rewinding and reassembly.
  • Transport and downtime: While the motor goes for rewinding, the line stops; in most businesses this stoppage is more expensive than the rewinding invoice.
  • Side parts: Parts such as bearings, terminals and cover gaskets are usually renewed.
  • Second-rewind risk: If the rewind quality is low, the motor may burn out again in a short time and the process starts over.
  • Excess consumption from efficiency loss: This item, which we will detail below, is usually invisible but the most expensive.

When these items come together, especially at small and medium powers, the "cheap" appearance of a rewind quickly disappears. That is why, when deciding, you need to consider not just the figure the rewinder gives but the total cost of ownership.

Let us think with an example: a frame-90, 1.5 kW motor has burned out. When the rewinding fee, bearing replacement, disassembly-assembly labor and a few days of line stoppage pile up; it is often both faster and, overall, smarter to buy a new motor that is zero-hour, warranted and in the IE3 efficiency class. Moreover, a new motor also resets the bearings and seats of the old motor, which had already reached the end of their life. By contrast, in a frame-160, 15 kW motor; if the frame and shaft are sound, a quality rewind can provide noticeable savings compared with a new motor. The decision must be made separately for each motor, according to frame size and continuity conditions.

The Most Critical Issue: Risk of Efficiency Class Dropping in a Rewind

Modern motors are produced in high efficiency classes such as IE3 and IE4, with precise winding geometry and quality core laminations. When a motor is rewound, if the original winding data cannot be preserved exactly, the motor's efficiency can drop. In other words, an IE3 motor may effectively behave like IE1/IE2 after rewinding. The result of this is that the motor consumes more electricity for every operating hour.

In a motor that runs continuously (S1), this efficiency loss turns over the years into an electricity bill far above the rewinding cost. Moreover, the IE3 efficiency class is legally mandatory at certain powers; a rewound motor with reduced efficiency also raises a question mark in terms of regulatory compliance. If you want to see the effect of efficiency classes on operating cost numerically, you can review our IE3 or IE4 investment analysis.

There is an important detail here: a qualified rewinding shop can largely sustain efficiency by preserving the original winding data. However, this requires measured equipment, the correct wire cross-section and experience; an ordinary rewind cannot guarantee it. So whether a rewind preserves efficiency depends on who the work is given to and cannot be predicted in advance. With a new motor, on the other hand, the efficiency class is documented on the nameplate; you know exactly what you are buying. On continuously running lines where efficiency is critical, this certainty is one of the strongest reasons that make a new motor attractive.

Post-rewind efficiency loss and the advantage of a new IE3 IE4 motor from stock

Warranty and Assurance: The Weak Point of a Rewound Motor

When you buy a new motor, you get a manufacturer warranty; if a problem arises, your point of contact is clear. With a rewound motor, there is usually no warranty, or it is limited to labor only. If the motor burns out again, you spend both money and time again. On a motor running on a critical line, this uncertainty is in itself a reason in favor of a new motor. We recommend evaluating what the warranty covers and what should be asked before purchasing together with our article on exact matching by nameplate information.

Delivery Time: When the Line Is Down, Time Is the Most Expensive Thing

A rewind can take days because the motor goes to and from the rewinder and the process is completed. In the busy season or at high powers, this period can even reach a week. If your production line is down during this time, the loss is often many times the difference between a rewind and a new motor. By contrast, supplying a standard power from stock is often possible the same day or the next day. Fast delivery from manufacturer stock, especially in an unplanned failure, turns the decision in favor of a new motor. We also cover the process of finding an emergency replacement motor in our reducer and motor supply content.

The Advantage of Buying a New Motor from the Manufacturer's Stock

When you decide on a new motor, buying directly from the manufacturer provides additional advantages:

  • Current efficiency class: A brand-new motor already comes in the IE3/IE4 class; it is compliant with regulation and economical in terms of energy.
  • Fast delivery: Standard powers can be shipped the same day from Turkiye stock.
  • Exact matching: An exact equivalent is found from the old motor's nameplate using power, speed, frame and flange information.
  • Warranty: You buy with manufacturer assurance.
  • Zero-hour mechanical parts: The bearings, shaft and seats come brand new; you do not continue with tired parts as in a rewind.
  • Opportunity to move to the right power: If the old motor burned out due to overload, you can solve the problem at the root by moving up one power level in the new motor.

HEM's standard electric motors and, for heavy duty, cast iron frame electric motors can be supplied from stock in a wide power range. If you want to replace an old-brand motor exactly, our second-hand or new stock motor comparison also sheds light on your decision. To see the whole motor family, you can take a look at our high-efficiency electric motors category.

Why Does a Motor Burn Out? Find the Real Cause Before Rewinding

Before the decision of rewinding or buying new, you need to understand why the motor burned out. Otherwise, whether you buy new or rewind, the same problem will recur. The most frequent burnout causes:

  • Overload: The motor power being insufficient for the application; running continuously above the rated current.
  • Phase loss: One of the three phases dropping out, the motor straining on two phases and burning its winding.
  • Lack of protection: The absence of a thermal or motor protection relay or its incorrect setting.
  • Bearing failure: A seized bearing straining and heating the motor.
  • Environmental conditions: Running with an insufficient protection class (IP) in an overly hot, dusty or humid environment.

If the motor burned out due to overload or wrong power selection, rewinding the same power or buying the exact same does not solve the problem; you may need to move up one power level or to the correct speed. For this reason, a new-motor decision is also an opportunity to review the right power and speed selection. Planning the protection equipment together with the motor prevents a second burnout.

The Annual Reflection of Efficiency Loss on the Business

How much electricity a motor consumes depends not only on its power but on its efficiency class. A continuously running motor has high annual operating hours; that is why even a small efficiency difference reaches a meaningful amount by the end of the year. A motor whose efficiency has dropped after a rewind, even if it apparently does the same job, draws more every hour. The business does not notice this at first because the bill increase is insidious and scattered; but as the number of motors increases, the total effect grows. That is why facilities undergoing an energy efficiency audit prefer new motors with a documented class over rewound motors with uncertain efficiency. If you want to draw up your facility's motor inventory by efficiency class, this process guides you in terms of both regulatory compliance and savings.

Decision Summary: Which One in Which Situation?

A practical summary:

  • Rewind: If it is a large frame (roughly 132 and above), high kW, the frame/shaft/casting is sound, a quality rewind is guaranteed and the efficiency class can be preserved.
  • Buy new: If it is frame 100 and below, a continuously running critical line, fast delivery is needed, and warranty and a current efficiency class are wanted.

This summary is a starting point; the final decision is determined together by the motor's condition, the criticality of the line and the delivery urgency. Rewinding some motors and renewing others in the same facility is completely normal. At the point where you are undecided, it is enough to send us the old motor's nameplate; we can evaluate together whether both rewinding and a new motor make sense. Remember, this decision is risk management as well as a financial calculation: continuing on a critical line with uncertain warranty and uncertain efficiency may look like a short-term saving but can cost more in the long run. At standard powers, a new motor from stock is the most predictable and least risky option for most businesses.

Frequently Asked Questions

Up to which frame size does rewinding a motor make sense?

The general consensus is to buy new rather than rewind for motors around frame 100 and below. Because at these powers the rewind cost approaches the value of a new motor, you get no warranty on top of it, and you face the risk of efficiency loss. At high powers of frame 132 and above, if the motor's mechanical parts are sound and a quality rewind can be done, rewinding can be considered. Even so, on a continuously running critical motor, most businesses prefer a new motor for reasons of efficiency and warranty.

How many years is the lifespan of an electric motor?

A correctly selected industrial electric motor, running in a suitable environment and maintained, has an average lifespan of around 15 years; in some applications it can be longer. For this reason, when a motor burns out for the first time and is still at the start of its life, replacing it with a new motor in a small frame; or, in a large frame, making use of the sound parts and rewinding, can make sense. For a motor that has burned out repeatedly, a new motor is generally more economical than continuous rewinding.

Does a rewound motor preserve its old efficiency?

In most cases it does not preserve it exactly. If the original winding geometry and wire cross-section are not applied identically, an IE3/IE4 motor can run at lower efficiency after a rewind. This means extra electricity consumption for every operating hour, and on continuously running motors the annual bill difference can exceed the rewind cost. On continuously running lines where efficiency matters, buying a new IE3/IE4 motor from stock is generally a smarter investment.

I burned out the same motor twice, should I rewind it again?

For a motor that burns out repeatedly, the real problem is usually not in the motor itself but in the conditions it runs in: overload, phase loss, lack of protection or wrong power selection. In this case, rewinding continuously wastes money and time. First identify the cause of the burnout; if necessary move up one power level, complete the protection equipment and start over with a warranted new motor in the right class. On a motor that has burned out twice, a third rewind done without solving the root cause will most likely bring a fourth.

Get a Quote

Send us the nameplate information of your burned motor (power, speed, frame, flange and brand); let us quickly inform you of both the exact equivalent new motor and the delivery time. With manufacturer assurance since 1979 and our Turkiye stock, let us make the right decision together. Call our line at +90 (532) 345 49 86 right away, or reach us through our contact us page.