Dennis,
Discharging directly into a low inductance short can cause the caps to experience reversal, currents, and prolonged ringing which may exceed the capacitors specifications and reduce life expectancy.
This is esspecially true with the larger energy storage caps. But the standard TC cap probably wouldn't have any issues. Good practice to avoid such occurances if you can.
So you discharge through a resistor. You ground one end of the resistor, such that if something strange is happening, it's just another layer of saftey. You do need a decent power rating. But 100ohm 100W resistors are plentiful.
Once everything is grounded happily, a storage short is placed on the cap to keep it from charging back up again, as can happen with the right conditions.
-Jay
Sent from my Verizon 4G LTE Smartphone
------ Original message------From: dennis otmaskin Date: Tue, Feb 13, 2018 6:26 PMTo: Tesla Coil Mailing List;Cc: Subject:Re: [TCML] Fwd: Bleeder resistor for Maxwell cap
re: Bleeder resistor for Maxwell capAgain, thanks everyone for the info.Jay I have a final question on your method shorting the capacitor through a*grounded* 100ohm 100w resistor. Not sure I understand why you'd need toground the resistor. Wouldn't it work to just put the resistor across thecapacitor terminals to short it? Do you have it grounded for extra safetyin the event the resistor fails?Thanks, Dennis Hopington MAOn Sun, Feb 11, 2018 at 5:07 PM, jhowson4 wrote:> Dennis, I may have a suitable resistor in my stash if you can't find one.> I just short my cap to ground through a grounded 100ohm 100w resistor on> the end of a insulating stick when im done for the day. Putting a gator> clip across it for storage. Been working for me for years.> Contact me off list of you want me to look for a resistor for you.> -Jay>> ------ Original message------From: dennis otmaskin Date: Sun, Feb 11, 2018> 4:37 PMTo: tesla@xxxxxxxxxx;Cc: Subject:[TCML] Fwd: Bleeder resistor for> Maxwell cap> Subject: Bleeder resistor for a Maxwell capThanks guys for your helpful> responses. To answer Gary's question, myMaxwell cap is .03uF (not .003uF> which was a typo in my earlier email).Here are the key points I take away> from your suggestions: - To keep it simple, I'll attempt to duplicate the> values of Gary'sbleeder resistor configuration: 78Meg, 1/4W. Since this> works for his.04uF cap it should also work for my .03uF cap...right? - I'll> use 2 or more separate sets of bleeders across the cap to act as asafety> back up. - I will also use use a bang stick each time for added safety> measure.I do have a question: in lieu of putting together a string of 39> resistorsas Gary has, I'd like to see if I can safely get the same value in> a singleHigh Voltage resistor. I've tried checking the product specs on> DigiKey's& Mouser's websites, but honestly it got a little confusing for me> with allthe additional specifications to choose from. Could one of you> suggest aspecific type of resistor that would do the job? If possible a> part numberwould also really be helpful.Thanks, Dennis MAOn Sat, Feb 10,> 2018 at 3:01 PM, dennis otmaskin wrote:>>>> Begin forwarded message:>>> *From:* Gary Lau > *Date:* February 7, 2018 at 10:30:18 PM EST> *To:* Tesla> Coil Mailing List > *Subject:* *Re: [TCML] Bleeder resistor for Maxwell> cap*> *Reply-To:* Tesla Coil Mailing List >> Hi Dennis,>> The specs for a> bleeder resistor are anything but critical. Was your cap> .003 uF or> .03uF? I use a .04uF cap. I constructed a bleeder out> of thirty nine> 2.0Meg 1/4W resistors (78Meg total). I calculated that with> my .04uF cap,> the time constant (R*C) is 3.2 sec. Five times the time> constant is> generally regarded as how long it takes to completely discharge> the cap.> My bleeder is pictured here, 5th photo from the top:>> http://www.laushaus.com/tesla/sync_gap.htm> 1/4W resistors are normally> not recommended for HV, but having so many in> series keeps the voltage per> resistor to acceptable limits. The important> thing is to make sure that> it's soundly constructed and wired to the cap.> 78 Meg is higher than most> multimeters can read so you need to be creative> in verifying that> sub-sections of the series chain are intact, thereby> implying that the> entire chain is wired intact.>> source=link&utm_campaign=sig-email&utm_content=webmail>>> Virus-free.> www.avg.com> source=link&utm_campaign=sig-email&utm_content=webmail>>> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>>> On Wed, Feb 7, 2018 at 1:40 PM,> dennis otmaskin > wrote:>> I would appreciate some guidance on the proper> bleeder resistor for a 35kV>> .003uF Maxwell pulse capacitor (#367667) or> where I can go to find this>> info. Thank you!>>> Dennis, Hopkinton MA>>> _______________________________________________>> Tesla mailing list>>> Tesla@xxxxxxxxxxxxxxxxxx>> https://www.pupman.com/mailman/listinfo/tesla>>>> _______________________________________________> Tesla mailing list>> Tesla@xxxxxxxxxxxxxxxxxx> https://www.pupman.com/mailman/listinfo/tesla> >_______________________________________________Tesla mailing> listTesla@tedward.pupman.comhttps://www.pupman.com/mailman/listinfo/tesla> _______________________________________________> Tesla mailing list> Tesla@xxxxxxxxxxxxxxxxxx> https://www.pupman.com/mailman/listinfo/tesla>_______________________________________________Tesla mailing listTesla@tedward.pupman.comhttps://www.pupman.com/mailman/listinfo/tesla
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