[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: Bleeder Resistors



Original poster: "Leigh Copp" <Leigh.Copp@xxxxxxxxxxx>

Have to agree with Q here.

Even on AC systems the capacitors have no direct discharge path except
for their own internal leakage resistance. I have inadvertently
discharged capacitors in series resonant tank circuits, and discovered
this the hard way. Interestingly enough, the adjacent, unused taps on a
tapped, oil filled capacitor hold a pretty good charge too - just ask my
erstwhile adjustable wrench :o)

(And, in hindsight this was pretty obviously electrostatic induction, or
capacitive voltage division, depending on where the tap was.)

Bleeder resistors are a must, and the design criteria you must juggle
are discharge time, and power dissipation. Smaller R is faster
discharge, but higher power dissipation. In a resonant circuit this will
also translate into lower Q of course.

Leigh



-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: January 2, 2006 1:32 PM
To: tesla@xxxxxxxxxx
Subject: Re: Bleeder Resistors

Original poster: "Qndre Qndre" <qndre_encrypt@xxxxxxxxxxx>

Bleeder resistors are used to drain remaining charge from the
capacitors in the tank circuit. If the remaining voltage after
shutdown of the NST is too low to make the spark gap fire, the cap
will not discharge into the primary and will hold a potentially
lethal charge. A bleeder resistor across every single capacitor in
the MMC will consume this charge turning it into heat which is better
than having several kilovolts across the capacitors being available
to shock you if you make adjustments to your system without shorting
out every single cap. Furthermore a capacitor can regain charge from
dielectric memory. The resulting voltage can exceed several hundreds
of volts since there are so many capacitors in series in an MMC.

Regards, Q.

----Original Message Follows----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: Bleeder Resistors
Date: Sun, 01 Jan 2006 21:49:01 -0700

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>




Bleeder resistor is not necessary unless you are running DC on this cap.

Dr. Resonance


>I am using a .03 uF / 35,000 v Maxwell capacitor on a 15/60 NST
>powered static gap coil.  Can a bleeder resistor be used on this
>type of cap?  If so, what type of resistor is needed?  I'd
>appreciate specs, brand, part number.  Thanks.  Dennis Hopkinton, MA