All in all, electric motors are some of the most reliable equipment around. They are used in almost every environment, including some very extreme environments. As a result, they can be damaged by getting contaminated by dirt, moisture, oil or grease. They can be installed incorrectly, mishandled, or even run in conditions that go beyond what they were built for. These situations can impact the motor control and cause many different types of problems which may require some troubleshooting.
One of the common problems encountered while diagnosing a motor for an electric motor repair is single-phasing in a three-phase motor. This occurs when one of the phase voltages has been lost due to a problem such as a blown fuse, a failure within the switching equipment, or when this happens with a variable speed drive, an open connection between the motor and the drive. This causes the other two-phase windings to take on more of the current load, which creates excess heat and which ends up stopping the motor (via blowing a fuse, or overheating and causing damage to the motor).
Because in most cases the motor still ends up running, you might not notice that there is an issue until it is too late. One way it might be seen is through the use of an infrared thermographic study. The overheating created by a motor which has lost one of the phase voltages is easily detectable by one of these infrared thermographic studies. Another way to diagnose this issue is to take current measurements on all of the phases using a digital multimeter.
The motor generates a current that can cause a “flashover” if the motor shaft voltage exceeds the insulation capacity of the bearing grease, to the outer bearings. This often results in the motor making loud noises and generating a lot of excess heat because of the increased friction in the bearings. If the flashover is creating excess heat, it can easily be detected through an infrared thermographic study, but the best way to quickly narrow down the problem is to use a portable oscilloscope to look at the voltage amplitude. This can reveal the problem by seeing an inconsistent pattern in the peaks of the waveforms.
Then get in touch with us here at Tekwell Services. We are electric motor service experts and can help you troubleshoot your stubborn electric motor control issues. Give us a call at 1-800-829-7454 or fill out our simple online form on our Contact page or for more information.