Re: HV Voltage Dividers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Eastern Voltage Research Corporation" <dhmccauley-at-easternvoltageresearch-dot-com> 


Marc,

You probably responded to the wrong address.  I recently changed to
dhmccauley-at-easternvoltageresearch-dot-com

Anyways, for PSPICE i used resistors and capacitors which included the
parasitic inductances and capacitances in each.

PSPICE will give you a ballpark idea of how the thing will work.
Also, yes, you can replace various components to get a perfectly flat
network.

However, in the real world this isn't the case.  Once you build the divider,
you will need to use a network analyzer, or similar and get the plant
response of
the entire unit, and then recalculate compensation values.  Its a lot of
trial and error and its the same way for the professional vendors as well.
Even the epoxy used in these things greatly affects the frequency response.

Dan


 > Hi Dan,
 >
 > I posted once this to you privately but you didn't answer. Here we go
 > again.
 >
 > I had a look at your voltage divider. I am wondering what model for the
 > resistors and the capacitors you are using in your PSpice simulations.
 >
 > I use MicroSim and the plain models that come with the evaluation
 > version. With those, I get a perfectly flat response just removing your
 > compensation network and replacing your C100 (25.3nF) with a 5.86 nF
 > value. Just using the RC=constant usual method.
 >
 > If you used some "real" models, could you please give me some
 > information on them? Maybe you had a run on a RLC analyzer on each R and
 >
 > C and made an equivalent network for them?
 >
 > Best Regards
 >
 >  > -----Original Message-----
 >  > From: tesla-at-pupman-dot-com [mailto:tesla-at-pupman-dot-com]
 >  > Sent: 1. huhtikuuta 2004 07:17
 >  > To: tesla-at-pupman-dot-com
 >  > Subject: Re: HV Voltage Dividers
 >  >
 >  >
 >  > Original poster: "Eastern Voltage Research Corporation"
 >  > <dhmccauley-at-easternvoltageresearch-dot-com>
 >  >
 >  >  > Instead of a HV probe, couldn't one just wire several resistors in
 >  >  > series, read the drop across one of them and just apply Ohm's/
 >  >  > Kirchhoff's law? Maybe those 10M resistors used for
 >  > draining the primary
 >  >  > caps? Three resistors will give 1/3 of the applied voltage
 >  > across any
 >  >  > single resistor; 4 resistors-1/4.  If you think the 4000V
 >  > label might be
 >  >  > correct, go with 5 resistors, a 1000V meter could do that
 >  > one.  I don't
 >  >  > know why I haven't done this myself, I have been putting
 >  > 120VAC into the
 >  >  > HV windings and measuring the output of the low voltage
 >  > side, and figure
 >  >  > my ratios.  I'm not sure how accurate this is, but it
 >  > seems to be pretty
 >  >  > close.
 >  >
 >  > If you are measuring DC or very low frequency (like 60Hz),
 >  > this might be
 >  > okay.
 >  > However, you won't get any type of good frequency response out of a
 >  > resistive
 >  > divider like this.
 >  >
 >  > To get an idea of some high voltage dividers I've built, see
 >  > the following
 >  > link:
 >  > http://www.easternvoltageresearch-dot-com/hv_divider.htm
 >  >
 >  > Dan
 >  >
 >  >
 >  >
 >
 >
 >
 >
 >