cachehiker
New Member
IIRC, R is usually chosen to be around 2 times √(L/C) for nearly critical damping. That's why a decent estimate of the winding inductance is needed. Without it one is shooting from the hip but I think paralleling two 300W 10Ω resistors would be in the ballpark.
With the resistors dissipating a good chunk of the first cycle's worth of ½LI² energy, the cap won't heat up quite so much.
Once upon a time, I worked through the gory details for the 50Ω / 10µF arrangement mentioned above. Nowadays, I'll just plug the values into LTSpice to verify the estimated power and voltage requirements but one still has to follow up with a scope.
10-20% errors here and there are no big deal. My LCR meter here at work has a 100mA test current option and the resulting estimates seem to be pretty close. My personal LCR meter at home uses such a small test current that inductance measurements on big motors (and large iron core inductors for loudspeaker crossovers) always come up low.
With the resistors dissipating a good chunk of the first cycle's worth of ½LI² energy, the cap won't heat up quite so much.
Once upon a time, I worked through the gory details for the 50Ω / 10µF arrangement mentioned above. Nowadays, I'll just plug the values into LTSpice to verify the estimated power and voltage requirements but one still has to follow up with a scope.
10-20% errors here and there are no big deal. My LCR meter here at work has a 100mA test current option and the resulting estimates seem to be pretty close. My personal LCR meter at home uses such a small test current that inductance measurements on big motors (and large iron core inductors for loudspeaker crossovers) always come up low.