Electric Motor: Repair or Replace

When a motor fails in facilities, engineering and maintenance managers will have to face a critical decision: whether to repair or replace it. To solve this problem, several aspects should be considered.


1. Consider the size of the motor.
Efficiency varies by motor size, with larger motors tends to have higher efficiency. Motors are often oversized for their function, meaning that they are not used at the full-load efficiency stated on their nameplate. Thus larger motor can be replaced by a smaller horsepower motor. An alternative is to install an adjustable speed drive (ASD) for the motor, which can yield 10% energy savings for refrigeration applications, 15% for air compressors, and 20% for pumps and fans. Undersized motor shall be replaced otherwise it will run hotter than normal, shorting its service life.
2. Consider the Rewinding Time
Careful rewinding can maintain and in some cases improve the motor efficiency. But in most cases, rewinding results in increased losses, which in turn result in reduction of efficiency, converting to greater energy consumption and increased operating cost. The number of rewinds is often thought to be a maximum of two or three. If a motor has been rewound many times, you might consider to replace the motor.
3. Consider the Downtime
Failed motors can lead to increased downtime and higher maintenance costs. Most motors are stock items and are soon available. But special, non-standard motors may take weeks or even months to be available for a replacement. Considering the huge production loss, it’s better to repair the motor instead of replace it.


4. Consider the Life-cost
Usually the initial purchase price of a motor represents no more than 5% of its life-cycle cost, and the operating cost accounts for over 90 percent. Thus it’s economical to replace an older, inefficient motor with a more efficient model, which will pay for themselves quickly in saved operating costs.
In this aspect, decision can be made by using software tools, spreadsheets and many other resources. Normally the result is a simple payback, which, if less than a specified time, replacement would be economical. With motor horsepower, load, efficiency, energy and demand costs in mind, you can do the calculation simply.
When you make a replacement, how would you deal with the old motor? Maybe you have considered to recover the copper winding but don’t have an efficient method. The truth is that there are equipment special for recycling the motor copper. Use our motor stator recycling machines, you can recycling stator winding.

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