I understand your need for simplicity but I think you should try out the clamp on ammeter method on a variety of motor types before recommending it to beginners in this field. Because excess capacity improves the overall power factor you are liable to finish up with too much capacity and excessive partload phantom phase voltage. Jim
I explained why I thought the ammeter approach may not work. Trouble is, as you suggested, the ferroresonance of the circuit could produce dangerous voltages under light loads.
The way I always heard it done was a light capacitor phase shift circuit to start the first three phase motor and then larger and larger ones cut in / started from the resultant phantom phase stability created from each successive larger motor load.
--------- A simple AC voltmeter would probably do the same thing.
When L1-2 = L2-3 = L3-1 are the same voltage you have 60 or 120 degree displacements depending how you want to look at it.
The currents may be different in the unit unless the 3 phase motor is totally isolated and run on it's own.
-------------
Have something to add? Share your thoughts — no account required.
Ask the community — no account required