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Registered Member #2563
Joined: Mon Dec 21 2009, 10:17AM
Location: Australia
Posts: 280
Hello all, if anyone has any larger DC capacitors rated 1Kv upwards, that are suitable for fast discharge, i wish to buy them. can pay by paypal or money order. Regards.
Registered Member #1886
Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73
I have a big maxwell energy discharge cap rated at 3.5KV 50uf. I've discharged it about 20 times blowing stuff up with no ill effect on it. Measured it with my multimeter and it showed 48.0uf. It can be yours for $80 shipped assuming that you live in the US. Pics:
Registered Member #1628
Joined: Wed Aug 06 2008, 08:48PM
Location: Huntsville, AL USA
Posts: 95
:-DI have 30 sangamo dc filter caps rated 2.25uf 15kvdcw. They weigh about 60 lbs each. Was planning to put them in parallel for 67.5uF at 15kvdc. About 7600 joules. Wasa gonna make a huge quarter shrinker, but if anyone is interested in them they can be for sale.!amazed
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Bamacoiler wrote ...
I have 30 sangamo dc filter caps rated 2.25uf 15kvdcw. They weigh about 60 lbs each. Was planning to put them in parallel for 67.5uF at 15kvdc. About 7600 joules. Wasa gonna make a huge quarter shrinker, but if anyone is interested in them they can be for sale.!amazed
Just out of curiosity, how much would you be selling those each? I do not have money for even shipping, and those are not gonna be cheap. I am, however, interested. If they will fit in one of the flat rate boxes, i will be very interested! I have always wanted a cap just like those, if i have the money i would buy 2. Do you think they would work for awhile as pulse discharge caps? I know that is not their intended use.
EDIT: nevermind about the flat rate, those things have big insulators anyway! But i would still like to know an estimated shipping price to TX and the price you want for each cap...
Also, be careful about those capacitors Coherent offered, they are not made for pulse and they could explode, and they will not last long in pulse duty. They are made for filtering HVDC. I am honestly not trying to keep Coherent from getting a sell!! Only time can tell how long it would actually last.
Registered Member #1886
Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73
Arcstarter wrote ...
Bamacoiler wrote ...
I have 30 sangamo dc filter caps rated 2.25uf 15kvdcw. They weigh about 60 lbs each. Was planning to put them in parallel for 67.5uF at 15kvdc. About 7600 joules. Wasa gonna make a huge quarter shrinker, but if anyone is interested in them they can be for sale.!amazed
Just out of curiosity, how much would you be selling those each? I do not have money for even shipping, and those are not gonna be cheap. I am, however, interested. If they will fit in one of the flat rate boxes, i will be very interested! I have always wanted a cap just like those, if i have the money i would buy 2. Do you think they would work for awhile as pulse discharge caps? I know that is not their intended use.
EDIT: nevermind about the flat rate, those things have big insulators anyway! But i would still like to know an estimated shipping price to TX and the price you want for each cap...
Also, be careful about those capacitors Coherent offered, they are not made for pulse and they could explode, and they will not last long in pulse duty. They are made for filtering HVDC. I am honestly not trying to keep Coherent from getting a sell!! Only time can tell how long it would actually last.
Are you sure about that? The original ebay auction I got it from clearly labeled it as a energy discharge cap and I've used it as such without it failing or anything. I wouldn't recommend it for a SG coil cap or anything, but it seems to work alright for blowing fruit up and stuff. See auctions like this for other caps like it.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
ScotchTapeLord wrote ...
Seems that pulses should be kept under 50kA. "General Purpose Pulse" is a bit misleading. 3.5kV = 50kA(R) R=.07... that's not far from a direct short. Someone correct me if I've overlooked something silly!
1. Thank you for providing reference to the datasheet instead of an Ebay seller claim.
2. Are you saying General Purpose Pulse is misleading because these caps support exceptionally fast discharge (7 us from full rated energy) in regular service?
3. Get used to small resistance numbers in pulse discharge apps. Usually the peak current is limited by inductance rather than resistance. One of these caps could make a pretty nice can crusher demo. Ballpark circuit values with 4 turn coil and -no- can would be R = .04 ohms, L = 2 uH, Zo = 0.20 ohms, peak current 17 kA, voltage reversal 75% - which is awful hard on the cap. With a regular soda can in the coil, if it stayed put (did not crush), the equivalent circuit would be R= 0.10 ohms, L = 1.3 uH, Z0 = 0.16 ohms, Imax 22 kA, voltage reversal 38%. (These based on low-energy measurements I once made with a 52 microfarad can crusher).
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Wanted Large Capacitors
I have 30 sangamo dc filter caps rated 2.25uf 15kvdcw. They weigh about 60 lbs each. Was planning to put them in parallel for 67.5uF at 15kvdc. About 7600 joules. Wasa gonna make a huge quarter shrinker, but if anyone is interested in them they can be for sale.!amazed
