If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529
For my rail gun project, i am using 3 cap banks of 900v 2750uf (its multistage). I was reading up on bleeder resistors, but i dont get the RC time constant. I want a resonably fast discharge rate, no more then 5min. charge is not an issue, im going to have a switch to disconnect the resistors while the cap bank is being used.
Registered Member #191
Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720
I assuming you are putting some lytics in series, if you plan on having a toggle-able bleeder, you should still have balancing resistors on the caps to keep the voltage even.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Backyard Skunkworks wrote ...
And if the R-C thing doesnt work out you can always start an emo site called bleeder network
What's the best thing about an emo lawn? It cuts itself.
BTW, half of the point of bleeder resistors is that you don't disconnect them. Having them always there is a good safety feature. For decent sized electrolytics running at hundreds of volts, I'd just connect a 100k resistor across each capacitor in the bank, to function as both bleeders and balancers.
And no, the discharge isn't linear, it's exponential. :P
Registered Member #158
Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282
If you want to discharge them quickly you can install a relay/contactor with resistors for a 'dump' option to discharge in 5 minutes or much less. And smaller valued resistors that take a little longer time to bleed down can be left permanently hooked up. I need to do this myself, so far I've gotten away with not using any bleeders/balancers and the biggest difference in voltage across 4 series stacked banks has been about 5V. But on my next project I want to start employing better practices. I think I'll make the dump a modular setup that I can use on various projects so long as the specs are fairly close.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
rp181 wrote ...
1 "bank" is 2 caps in series =). How can i calculate balancing resistors?
Balancing resistors are chosen so that the current running through them is at least 10x the leakage current spec of a single capacitor. This is a general rule.
If the leakage current is specified as 100uA for a cap, than the resistor should be chosen so 100uA*10 = 1mA is flowing through the resistor.
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
For the electrolytics commonly used here (e.g. 3000uF 400V) the leakage current tends to be around 1mA. If you'd want 10mA balancing current you probably be better of with 47k across each cap, especially since the caps leak a lot more if they are charged only intermittently.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
bleeder network
