When it comes to motor troubleshooting your meter likely isn't enough to figure out the issue completely. The usual testing of lead to lead to check resistance and lead to ground to see if there is a short can definitely find some, but not all motor motor-related issues. The problem is the signal that a standard meter sends down the line and between the windings is often too weak to simulate what would normally be happening during operation.
Most meters are only going to put a few volts down the line to test for resistance. In some cases this is fine. In cases where there is a small break in the insulation that only appears under load, it is insufficient. This is when a megohmmeter(also called a megger) comes in handy. These are true insulation testers and send a much higher voltage signal down the line. With this high voltage, they can really test the quality of the insulation that a normal meter would miss.
It's not an everyday tool unless you have a ton of motors in a harsh environment, but there is nothing like it when you need it. A megger will tell you right away if it's the motor or wiring feeding a motor pretty quickly. It's a worthwhile investment, even if you use it just once a year. Figuring out it's a wiring issue and not a motor issue in a few minutes, as opposed to replacing a motor you suspect is bad is an easy win. The other side of that is confirming it's a bad motor quickly without testing all the contactors, feeds, VFDs, or other integrated equipment, which can save so much time, which in a factory is big money.
While they are fairly simple to use, they do need a bit more caution than normal meters. Since they send a higher voltage signal down the line, you have to be especially careful of where the leads are. Most of these devices will send up to 1,000 volts down the line. Be sure to read the manuals and exercise caution.
Hopefully, you've learned something about this wonderful tool and its applications.
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