The pressure on businesses to operate more efficiently both in terms of internal processes and environmental commitments is growing. For those working in energy management, a very real concern is the efficiency of their electric motors.
Even with preventative methods in place, electric motor failure is common — and when it happens, it has a huge impact. As machines grind to a halt, productivity ceases and losses and repair costs mount. Given the severity of the situation, it’s very easy to make a panicked decision over whether to rewind and repair or replace your motor.
So what should these motor owners do? With new high-efficiency motors available, do they take the plunge and invest in a whole new motor that promises higher efficiency levels but with significantly greater costs? Or, do they commit to a motor repair or rewind? While the cost is often lower, many are concerned about the potential inefficiencies that an electric motor rewind can bring — yet are these worries grounded in fiction?
This widespread misconception is centred around a small study of smaller motors . It is claimed that carrying out a rewind can drop efficiency by between 1% and 5% each time it is rewound. Considering the associated expense and sheer volume of energy these motors use, this is naturally concerning. However, more recent research has countered these findings.
A different study was carried out by EASA and AEMT in association with Nottingham University and involved 22 new motors from 50 to 300 hp. Overall, the results found that when electric motors were rewound using good practice, there was no significant change in the efficiency of the motors. However, in some instances, efficiency actually increased. This clearly dispels the belief that a rewind is actually detrimental to a motor’s performance.
How to decide whether to rewind, repair or replace
Before you shell out on an expensive electric motor, consider first that it might not be necessary. Of course, in cases of catastrophic failure, this may be your only option. However, it’s very important to fully evaluate your options to make sure that you make the right choice in terms of operation, cost and efficiency. This can be done by considering the following areas, as explained by Houghton International.
The suitability of your electric motor
You’ll know better than anyone how your operational needs have shifted over time, rendering your existing motor unsuitable. Review the scale of the damage alongside the requirements for the motor’s processes and duty cycles. If the motor is no longer suitable or too damaged, your option is to replace the motor.
The stator core and rotor condition
It’s important to check the condition of the stator core and rotor. If significant damage is present, it may be more beneficial to purchase a new motor, as depending on the extent of the damage, repairs can be costly.
When it comes to buying a new motor, thoroughly consider your options. For example, if the lead times for the motor you need are long, you may to decide to repair rather than replace to minimise downtime.
Damage to other mechanical parts
Other parts can become damaged during motor failure, including the shaft, frame, bearing housing and other mechanical parts. Examine the extent of the damage; you may be able to replace the affected parts at a lower cost than replacing the entire motor.
EPAct or Nema Premium motor?
If you have been debating whether to replace your motor for a little while, failure could be the reason you have been looking for. If you are considering making the investment, make sure you fully understand the return you’ll receive from doing so. Consider the energy savings you’ll make alongside the expected life of the motor and its hours of operation. Always consider your overall budget too, to make sure the replacement aligns with your current financial position.
With this in mind, remember than an electric motor rewind will not significantly impact the efficiency of your motor if it is carried out by a qualified service centre. If you are happy with the efficiency your motor delivers, this could be the option for you.
Making the right choices with your needs, budget and timescales in mind can put an end to unnecessary downtime and costs in your business.
