Field flux plot test
Field flux plot test
(OP)
I have yet another question. Can anyone please explain how a field flux plot test is done and why? Thank you.
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RE: Field flux plot test
To clarify, this application is on a non-sailent pole type rotor?
Yes, I can explain.
RE: Field flux plot test
Actually its for salient pole hydro electric generator. But if you could explain the non salient pole rotor.... that should give me some idea.
Thank you.
RE: Field flux plot test
The first thing you need is a search coil that can be placed on the rotor preferably near the active center of the rotor. This search coil is usually about 2 inches in diameter and has about 200 to 400 turns of fine wire wrapped around its wooden or air core. The leadsare fed to the input to an oscilloscope.
You now need a 60 Hz (or 50Hz as available) connected to the slip rings of the rotor. This is usally done through a variac, to adjust the current/voltage to the rotor circuit. Also place an AC volt meter across the scope terminals to accurately measure the search coil voltage. With AC exciting the rotor winding, start at the edge of the pole. Adjust the scope such that you have 2 full cycles on the screen. As you move the search coil around the the circumference of the rotor you will note the magnitude and direction of the search coil will change by reading the phase angle on the second zero crossing on the scope.
Do this at the first edge of the pole, center and the other edge of the pole, jump to the next pole and the direction changes, i.e. N and S.
RE: Field flux plot test
Do you know of a web link that may contain information on this test procedure.
Thanks a million for taking the time to write the procedure.
RE: Field flux plot test
I would further add if you are trying to determine shorted turns on your generator/synchronous motor there is an easier way that is fool-proof.
RE: Field flux plot test
Sarg
RE: Field flux plot test
Remember that when you use ac, you are dealing with the impedance of the circuit of which the iron is part. The dc test is only the wire of the winding.
To go deeper, it is very easy to calc what the resistance drop should be. For example 120VDC and 10 poles gives 12DCvolts per pole. Typical mfg tollerance was +/- 2% as a go / no go.
RE: Field flux plot test
Thanks.
Sarg