Re: [CAD_CAM_EDM_DRO] Re: LARGE DC MOTOR speed control question

In a message dated 7/16/00 7:44:29 AM Mountain Daylight Time,
SMCDONAL@... writes:

<< I out the cap on the input of the
rectifiers instead. >>
NO, they will blow up.
The purpose of the caps on the output is to store electrons between input
pulses from the rectifiers, they call them filters.
It is like using a hand pump to fill a bucket of water with a pipe running
out the bottom of it, the bucket acts as a surge pond and allows the pipe to
drain water with a smooth flow, the filter capacitor does the same thing. It
should only be placed on the output. The other variable is are you using
half wave or full wave rectifiers, as this also makes a difference.
Capacitor size can be computed but not by me, I would hang enough on to do
the job, make sure the voltage is higher than the output of the rectifiers,
and that the correct polarity is observed.
The correct output voltage is Input Volts (RMS) x 1.414 equals voltage the
capacitor will see, however use a higher voltage, about 3 times the input
voltage minimum.
bill