How to Replace an Overloaded Motor

So, you think your electric motor failed from being overloaded. After verifying that the failure is due to an overload, you must find the source and correct the issue before installing your replacement motor.

Some common causes of electric motor overload are:

• Too much load on the shaft, whether from misalignment, worn bearings, or not enough torque to drive the output equipment. For example, we’ve seen this happen in an industrial laundry facility. If a particularly heavy load requires more torque than the motor can bear, the motor can only be overloaded for so long before it overloads.
• Too little input voltage, causing the motor to attempt to draw more current, overcompensating so it can provide enough torque at the output.
• Too much voltage, resulting in excessive current within the motor's windings, causing an overload.

Has My Motor Failed Due to Overload?

Verify overload - this is the first point to investigate. Your motor may look just fine, but you’ll smell or hear something unusual. And your motor may be louder and have additional vibration as the shaft works harder to turn the load. The temperature will likely increase. If you already have overload measures in place, you'll find that the motor will no longer start because of a tripped relay, circuit breaker, or blown fuse.

A failed capacitor is a sign that your motor may have failed due to overload. Below is a pair of capacitors taken from an overloaded motor.

In our previous article, What Causes Motor Overload, we go over ways to detect an overload before and after a failure has occurred. And we cover the different mechanical and electrical overload types, such as bearing wear, shaft misalignment, and over- & under-currents. After completing a few electrical and visual checks, you should be able to pinpoint the source of failure on your electric motor. Then you'll be more empowered to make a motor replacement that is sure to last a lot longer, work more efficiently, and make you more money.

How to Test for Motor Overload

Test the input voltage and current of the motor using a multimeter. This must be tested at the motor to ensure that the power source and cabling provide a proper, non-fluctuating voltage and that the motor is not attempting to draw additional current.Your motor should not measure more amps that the FLA (full load amps) indicated on the motor nameplate, unless your motor has a service factor higher than one. In this case, short periods of overload are acceptable.

Testing with a multimeter also gives the opportunity to ensure no faults are coming from any motor controls you may have in the circuit series. This test should be conducted the next day again and on a periodic schedule to give you the chance to catch a fault before it leads to a failure, and it will also help you discover the source of the fault after a failure.

Your electrician will test the input voltage and current of the motor upon installation. This must be tested at the motor to ensure that the power source and cabling provide a proper, non-fluctuating voltage and that the motor is not attempting to draw additional current. This also gives the opportunity to ensure no faults are coming from any motor controls you may have in the circuit series. This test should be conducted the next day again and on a periodic schedule to give you the chance to catch a fault before it leads to a failure, and it will also help you discover the source of the fault after a failure.

Your certified electrician should also ensure that your circuit has overload protection, such as a thermal overload relay, to help protect your valuable equipment. When it comes to specialized electrical testing, it's best to consult an expert like a certified electrician, particularly if you hope to make a warranty claim.

Ensure an Overload Device is in Place

Many manufacturers have Authorized Service Locations; these are your local electric motor rewind and repair businesses approved to carry out warranty services on behalf of the manufacturer. This allows for shorter warranty claim times and faster repairs, as you won't have to send your motor to the manufacturer's location in the US or even further. You'll likely be working with an Authorized Service Location when making a warranty claim on your failed motor.

Your Authorized Service Location will complete an inspection of the failed motor and advise if the damage is covered under warranty or not. Unfortunately, if your motor has failed due to overload damage, it will not be covered under warranty. Manufacturers have it written into their warranty documentation that they will not cover damages due to overload, the only exception being if a manufacturer defect caused the overload. When we receive a warranty request and inspect the motor, we’ll do our best to tell you why the motor failed so that you can avoid overload moving forward.

Manufacturers have been advancing motor and control technology for decades to find a solution to overload failures. You'll find ratings on your motor nameplate like service factorthat tell you the exact allowable limits for overload, along with other motor control technology and relays that help avoid overload damage. When you're running your motor with these manufacturer measures in place, your motor will be within the warranty coverage.

How to Find a Replacement

Summary

To keep your electric motor under warranty, you must avoid damages due to overload situations. No matter the specific cause of the overload, it's highly likely the manufacturer won't cover your motor under warranty. Understanding your application's requirements and your chosen electric motor's ability is paramount in keeping your equipment running efficiently and damage-free. Having a certified electrician perform regular electrical tests and ensuring you have appropriate overload protection in place will save you money and future frustrations.

Not sure how to match your application to the perfect electric motor? Contact our experts, and they will help you get your operation up and running and keep you within your warranty coverage.