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Variable HVDC supply

Variable HVDC supply

Variable HVDC supply

(OP)
Does anyone know how to build or buy a variable high voltage DC supply up to 30kV for charging capacitors?

RE: Variable HVDC supply

Suggestion: KWs will affect the technology and principle selection.

RE: Variable HVDC supply

Just curious, why does an automotive engineer want to charge a cap to 30kV?

RE: Variable HVDC supply

There may be some extra big gap spark plugs.

RE: Variable HVDC supply

There are lots of suppliers for this specific kind of equipment. It is a quite common application to charge a capacitor to a high DC voltage. I wouldn`t try to build a supply myself unless there are special requirements.

Please post some more data:

capacitance to be charged
repetition rate
input voltage

RE: Variable HVDC supply

Capacitance is 0.2 microF, 6kV

Never fully discharged, short pulses at hundreds to thousands of Hz.

RE: Variable HVDC supply

I wouldn't try to charge a 6KV capacitor up to 30 kV unless I want to test it !

RE: Variable HVDC supply

Suggestion: There will be a significant difference in the dc power supply wattage for 6kV (72Watts plus some design margin) and for 30kV (1800Watts plus some design margin); required to charge 0.2microF capacitor.

RE: Variable HVDC supply

jB,

I can't follow your reasoning on the power requirements: the steady-state power consumption of a capacitor is zero, other than dielectric leakage resistance. Ergo, a power supply of any practical power rating whould eventually charge up the capacitor to supply output voltage. A PS with a lower output current would take longer to charge the capacitor than one a more powerful PS, but the required charging time was never stated.

How do you get such specific power ratings for the power supplies from the information psted?

-----------------------------------

Start each new day with a smile.

Get it over with.

RE: Variable HVDC supply

Ideally an adjustable 30kV supply, but 6kV will do for some tests. I have had some success and am building circuits presently.

RE: Variable HVDC supply

Suggestion to ScottyUK: Visit

http://www.aerovox.com/technical/T11.html
for: storing high electrical energy in capacitors

http://www.aerovox.com/technical/T8.html
for: high energy storage capacitors

etc. for more info

Capacitor Energy in Wattseconds or Joules = (1/2) C x V x V
where
C is capacitance
V is voltage
Therefore, capacitor energies will be 36 Joules or Wattseconds and 900 Joules or Ws in my previous posting.
Since:
Energy = (1/C) x integral from 0 to Q of QxdQ=(1/2)x(1/C)xQ^2=(1/2) x C x (V1-V2)^2=(1/2) x C x V^2, in Joules or Ws, for a plate capacitor.

RE: Variable HVDC supply

jB,

Thanks for the reply. However, your earlier post explicitly used the word 'watts' not 'watt-seconds', making your initial statement meaningless.

-----------------------------------

Start each new day with a smile.

Get it over with.

RE: Variable HVDC supply

ScottyUK,

As regards answering my initial posting, your point-scoring attempt at jbartos makes your last reply meaningless. I hope you have youth as an excuse...

cculley

RE: Variable HVDC supply

cculley,

Point-scoring, or correcting inaccuracy? Interpret as you will.

Regarding buying power supplies, it would help immensely if we had some idea where you were located. I could name several possible suppliers in the UK, but that would be of little use if you are in the US or Australia, or wherever. Personally, I would have some serious thinking to do before building such a unit if it was to be used by others in a work environment, purely from a liability point of view.

Some of the best lab-type HV power supplies were made by Kingshill, although my quick look through Google doesn't pick them up. Perhaps they are no more. There are definitely quite a lot of their supplies out there on the surplus market. Your later posts seem to indicate you're really after a high frequency, high voltage pulse generator rather than a normal DC power supply.

From the fairly pulse rate you need, a transformer circuit with the control done on the LV side sounds most feasible. The high repetition rate seems to rule out the tripler circuits. What circuit topology are you trying to use at present?

Haefely used to (still do?) make HV testing equipment which might be closer to what you are after, provided they can achieve the repetition rate.



As for youth? More than some, less than others.

-----------------------------------

Start each new day with a smile.

Get it over with.

RE: Variable HVDC supply

Thank you ScottyUK,

I will websearch the suppliers you mentioned and I will be more specific about my testing purposes in my next posting.

Regards,
cculley

RE: Variable HVDC supply

Two more companies in the HV laboratory PSU market, after a quick phonecall to a colleague to jog my memory:

http://www.glassmanhv.com/products.shtml

http://www.brandenburg.co.uk/

I had a look at the Haefely website after posting. They seem to have gone quite specialist in the ultra-high voltage testing field, and into EMC. I should have checked prior to posting - sorry for the bad info.

-----------------------------------

Start each new day with a smile.

Get it over with.

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