Many kinds of electrical issues can cause a motor to overheat. These include voltage imbalance, low voltage, low power factor, and waveform distortion. With the right test equipment, you can easily identify these problems.
But correcting them may be another story. Doing so will often require an investment of time and money, plus some downtime that may be hard to obtain. At least for the short term, simply increasing motor ventilation may reduce the excess heat enough to prevent premature motor failure.
This leads to another point—the motor ventilation may be inadequate to start with. Even if there are no electrical issues causing excess heat, the fact the generated heat stays there instead of dissipating may lead to premature motor failure in an otherwise good system.
So before you make the hookups to test for power, look at the thermal landscape. You may be able to spot some issues with the unaided eye. For example, the motor may be so buried in the equipment that there’s no airflow (air supply ducting can correct this) or if it has air supply ducting, the filters may be dirty. Such issues are worth noting, but don’t take corrective action until you’ve used thermal imaging to determine exactly what’s going on.
Having a thermal image of a motor and all the surrounding area will, for example, help you pick a good source for the cooler air you’ll duct in. The imaging may show you that, instead of running a lot of bulky duct across the equipment to the motor, what you really need to do is hood and vent one particular heat source.
Thermal imaging of the entire area, in other words, prevents expensive guesswork when developing a solution. And after you've made the corrections, thermal imaging lets you see if the solution works as intended. That sure beats waiting for another motor failure to tell you that, oops, it wasn’t enough.