Medium Voltage Motors Coils Data

How about a digital multimeter set to ohms?

Actually that can be useful for a motor you cannot open up, but a more correct way is to use a lower voltage AC supply and calculate the impedance or Henries......especially if you can pop the coil off the stator or whatever, not always possible though.....

The size or better said the thickness of the winding wire and the number of turns can also be useful info.....again, not easy to do.

I feel we need more info as to why you need to do his....

If is just to identify like components, then the Ohmeter method will be just fine, provided it goes down accurately under one Ohm......Micro Ohms in fact as a lot of motors have very low resistances...

dear sir

thank you to your interest and i will take your advise seriously but there was a mistake from me because i mean by measuring the coils is not test it but i mine the dimension data of it (length-width-angles.........)that i mean by measuring .

then i hope you understand now my needs and i hope you help me in that .

not:

i have a data sheet for the coil dimension and i didn't now how i can use it.

dear sir

thank you to your interest and i will take your advise seriously but there was a mistake from me because i mean by measuring the coils is not test it but i mine the dimension data of it (length-width-angles.........)that i mean by measuring .

then i hope you understand now my needs and i hope you help me in that .

not:

i have a data sheet for the coil dimension and i didn't now how i can use it.

Assuming Medium Voltage = 1 to 15 kV it is good to have in your "motor inventory card" at least two values:

R (resistance in Ω ohms) measured by accurate Ohmmeter (at least 0.% accuracy)

Z (impedance in Ω too) = V/I (Voltage / Current in V/A),the value received from technical method as mention before having simple measurement of applied voltage (by Voltmeter) and the current in the each of phase winding (or two-phase in series in common point is not accessible - rear situation). Be sure your V and A meters have good accuracy too.

Doing these measurement periodically you monitor and eventually locate motor malfunctions as shorted coils or leakage to the metal construction of the motor.

Also each phase insulation should be checked by Mega-Ohmmeter (or so called Megger). For kV rating motors it is recommended the 60 sec HighVoltage test. For prevention.

Old type winding insulation materials were easy to drop their R isol because of humidity.

dear sir

thank you to your interest and i will take your advise seriously but there was a mistake from me because i mean by measuring the coils is not test it but i mine the dimension data of it (length-width-angles.........)that i mean by measuring .

then i hope you understand now my needs and i hope you help me in that .

not:

i have a data sheet for the coil dimension and i didn't now how i can use it.