Re: Homemade Voltage Divider

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Dr, all,

Yes, this is true, but when you're measuring the
voltage of a charging capacitor bank at the
capacitors' terminals while charging the caps
up, the measured voltage will be considerably
lower than the applied voltage until the caps'
charge voltage reaches equalibrium with the
charging supply voltage. This is due to the
heavy load that the caps place upon the power
supply while charging and also the reason that
the power supply's voltage must reach higher than
the desired charge voltage of the caps. Otherwise
it would take an excessive period of time to fully
charge the caps if the maximum available supply
voltage was only about equal to the max charge
voltage of the caps. Since the power supply's
voltage must reach higher than the caps' rated
voltage, the measured DC voltage at the capacitors'
terminals must be measured and the power supply
immediately shut off when the voltage at the caps'
terminals reaches their rated voltage to prevent over-
volting of the caps, thus my reason for measuring the
DC voltage at the caps' terminals.

Also, I was wanting to know if I would need some
type of HV resistor in series with the HV DC input
to the caps since the bombarder transformer supply
isn't current limited? I would gradually ramp up the
voltage input to the bombarder with a variac while
monitoring the voltage at the caps' terminals but the
bombarder can act almost like a dead short while
charging >400 µFd of capacitor towards 10 kV
until the capacitors' charge gets close to the applied
voltage. I have a ~250 watt, 3 kOhm resistor that I
could use. Would this be about the right size and
resistance for this purpose?

Thanks,
David Rieben



----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, January 31, 2006 10:35 PM
Subject: Re: Homemade Voltage Divider


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


You never need to measure the DC voltage.  It's
always 1.414 x the Erms, so you are actually
measuring Erms and then just recalibrating the
meter face to reflect the actual measured DC
potential.  No messing around with HV resistors, etc.

Dr. Resonance



When I mentioned the NST method I was thinking he
wanted to measure the AC input to the DC filter -
didn't engage brain. Transformers don't work well at DC.
Jim
----- Original Message -----
From: <mailto:tesla@xxxxxxxxxx>Tesla list
To: <mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx
Sent: Saturday, January 28, 2006 12:00 PM
Subject: Re: Homemade Voltage Divider

Original poster: Yurtle Turtle <<mailto:yurtle_t@xxxxxxxxx>yurtle_t@xxxxxxxxx>

An NST will work for AC, but not DC.

Adam

--- Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:

 > Original poster: "James Zimmerschied"
 > <<mailto:zimtesla@xxxxxxx>zimtesla@xxxxxxx>
 >
 > I am pondering a way to reliably measure 10 KVDC
 > across the terminals of (2) 100 µFd energy dis-
 > charge caps Original poster: "David Rieben"
 >
 > David
 > Richard Hull showed the use of a NST is reverse
 > to measure high voltages. This might be bulky but
 > reliable.
 > Jim Zimmerschied
 >
 >
 >