How do you check a 3 phase motor?

Answer 1

Depends firstly on the type of motor and secondly what your testing for.

If you are the manufacturer, you test according to the IEC/AS Codes for electromechanical machines.

Considering just one type of 3 phase motor, the Squirrel Cage: if you are testing it electrically, then first of all you have to check the insulation resistance of each phase to earth with an appropriately sized megger (insulation tester). Then you measure the stator's winding resistance between each phase. (You don't check the phase-to-phase on the rotor as it's basically a dead short for Squirrel Cage motors.)

If you are load-testing, depending on the codes you are following, you start it up and run it for around 8 hours. During this period you take temperature measurements on the windings and the bearings and vibration measurements of the bearings. For the stator windings, you just measure the temperature of the stator housing unless the motor is big enough to have its own set of built-in RTDs. (Remote Temperature Detectors.)

Answer 2

You use a megger. This allows you to check what the condition of the insulation of the motor windings are. It is an insulation test to see is the insulation has been injured in any way to cause a short circuit when normal power is applied to it. On my megger there are 3 ranges 300V, 750V, and 1000 volts. Applying the proper voltage is essential to not damaging the device you are testing. Working voltages up to 240 volts should use the 300 range. Working voltages up to 600 volts use the 750 volt range and working voltages above 600 use the 1000 volt range. As you can see if you used the 1000 volt range on a device that had a working voltage of say 24 volts you could damage the insulation just by testing it. Connect one lead of the megger to the frame of the motor and the other lead to the end of the coil winding. If the motor has a start and run winding both coils must be checked.

Answer 3

If by using the word "check" it is meant to establish the condition of the motor in an operative state, then there are a couple of things that can be done. The very first thing is to measure the amperage that the motor is drawing and compare that value to what the manufacturer recommends on the motor's nameplate. The second and important thing to do is establish the condition of the motors windings to ground. This is done with a megger. Continuous readings over the life time of the motor will show a continuous degrading of the insulation capacity of the motor' internal windings. When the readings get low enough, at some point in time the decision has to be made as to whether it is time to replace the motor before the windings short circuit and there is a total motor failure. In large industrial installations this type of preventative maintenance prevents production line shut downs.

Answer 4

To check a 3-phase motor, you can perform tests such as checking the continuity of windings, measuring resistance values across phases, and inspecting for any physical signs of damage or wear. Additionally, you can use a multimeter to assess the voltage and current levels during operation to ensure they fall within the expected range. If the motor is not functioning properly, consider consulting a professional for further diagnostics and repairs.

Answer 5

Go to your local marina, and connect to the 3 phase shore power there. If the motor spins at proper speed, you should be good.

Answer 6

how to test starting and running windings

Answer 7

with a muiltermeter.