Capacitances of various coil sizes for AC hipoting
Capacitances of various coil sizes for AC hipoting
(OP)
I realize that with an infinite number of coil geometries, wire sizes, designs, voltages, etc that it is impossible to know the capacitance of a coil to estimate the AC voltage charging current necessary to hipot it, but, does anyone have any rough rules of thumb that might define even a dozen typical sizes of coils, probably stators mostly? Possibly someone has worked out a few examples of motor or generator coils based on voltage rating, MWs, HP, diameter, # of turns, etc for a few voltage sizes: 2400V, 4160V, 13.8 kV, etc. Also, do many motor shops perform power factor testing on rewinds? Thanks.





RE: Capacitances of various coil sizes for AC hipoting
Energize the coil through a high value resistor with a fairly low DC voltage. Measure the time constant and from that calculate the capacitance. Don't forget the discharge diode.
Bill
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"Why not the best?"
Jimmy Carter
RE: Capacitances of various coil sizes for AC hipoting
RE: Capacitances of various coil sizes for AC hipoting
Another thought would be to test with low voltage power frequency ac if that is readily available.
Rough estimate can be made using parallel plate capacitor model C = epsilon * A / d
Area is the total area of all core slots.
d is ground insulation thickness
epsilon between 2 and 4 times epsilon0. I think epoxy mica vpi insulation system would be towards 4.
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(2B)+(2B)' ?
RE: Capacitances of various coil sizes for AC hipoting
thread237-278636: How to calculate motor capacitance?
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(2B)+(2B)' ?
RE: Capacitances of various coil sizes for AC hipoting