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Re: Capacitor Safety Discharge Method (fwd)



---------- Forwarded message ----------
Date: Wed, 8 Aug 2007 12:55:37 -0700
From: Ray von Postel <vonpostel@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Capacitor Safety Discharge Method (fwd)

Bart:
"What he said."  Thanks for saying it. Perhaps some one will take it to 
heart.
Ray

On Aug 8, 2007, at 7:27 AM, Tesla list wrote:

>
> ---------- Forwarded message ----------
> Date: Tue, 07 Aug 2007 01:41:31 -0700
> From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Capacitor Safety Discharge Method (fwd)
>
> Hi Ray,
>
> Shorting caps is to keep you safe, yes. But shorting "charged" caps
> without bleeding them down causes plate forces within the cap =
> disforming the plates which reduces the caps integrity and C tolerance.
> Bleed charged caps first, then mechanically discharge in some fashion.
> The reasons are clear. Bleeders are not safety devices. So don't think
> of them that way. However, in numerous equipment they are often 
> inserted
> by engineers as an attempt at safety (buyer beware). They are never the
> final word. If you rely on them for safety all can quickly go bad. None
> of this indicates they shouldn't be used, they just shouldn't be used 
> as
> your safety line.
>
> The only reason I posted to this thread was that someone said bleeders
> should never be used. That was probably not what was meant. He probably
> meant they should never be used as a safety line. However, I just 
> didn't
> want coilers to think bleeders were a bad thing, because their not. 
> They
> are often necessary.
>
> In most of our TC circuits, our tranny's provide the bleeding action 
> and
> only a shorting safety action is required before touching anything.
> There are "some" circuits that can retain a charge and then bleeders 
> are
> definitely a good idea (not for safety, for cap health). Pretty simple
> logic.
>
> Take care,
> Bart
>
> Tesla list wrote:
>
>> ---------- Forwarded message ----------
>> Date: Mon, 6 Aug 2007 21:45:35 -0700
>> From: Ray von Postel <vonpostel@xxxxxxxxxxx>
>> To: Tesla list <tesla@xxxxxxxxxx>
>> Subject: Re: Capacitor Safety Discharge Method (fwd)
>>
>> Guys:
>>
>> You are shorting out capacitors to keep from frying yourselves. What 
>> is
>> the safety logic of putting some resistors in the circuit?
>>
>> Ray
>>
>> On Aug 6, 2007, at 7:54 PM, Tesla list wrote:
>>
>>
>>
>>> ---------- Forwarded message ----------
>>> Date: Mon, 06 Aug 2007 20:38:11 +0000
>>> From: nancylavoie@xxxxxxxxxxx
>>> To: Tesla list <tesla@xxxxxxxxxx>
>>> Subject: Re: Capacitor Safety Discharge Method (fwd)
>>>
>>> Hi, Chris. Thats exactly what I was trying to get an answer to in the
>>> previous posts and I think that if you kind of read between the lines
>>> in
>>> Bart's reply, you can see that its probably okay to do if you use
>>> bleeder
>>> resistors and discharge the cap after the charge has bled off. What I
>>> wanted to use was a Ross Engineering relay rated at 40 kv (normally
>>> open
>>> contacts) and wire it across the terminals of the capacitor and
>>> resistors.It would then just be a simple matter of flipping a switch
>>> and
>>> doing the work of the screwdriver in a much safer fashion.Anyone see 
>>> a
>>> problem? Wyatt
>>>
>>> -------------- Original message --------------
>>> From: "Tesla list" <tesla@xxxxxxxxxx>
>>>
>>>
>>>
>>>> ---------- Forwarded message ----------
>>>> Date: Mon, 06 Aug 2007 01:53:57 -0400
>>>> From: Crispy
>>>> To: tesla@xxxxxxxxxx
>>>> Subject: Capacitor Safety Discharge Method
>>>>
>>>> Hello,
>>>>
>>>> In light of the recent discussion about the necessity of a manual
>>>> discharge for the tank capacitor in addition to bleeder resistors,
>>>> I've
>>>> been considering an easier method of manual discharge than the
>>>> stick-a-screwdriver-in-the-spark-gap method for my coil. I was
>>>> thinking
>>>> about an electronic method, and here's the idea. Would it be 
>>>> possible
>>>> to have a linear pull-style solenoid with an electrode that, when
>>>> powered, would retract its electrode from another static electrode, 
>>>> to
>>>> act as the safety discharge? The normal state (no electricity 
>>>> applied)
>>>> would be to have the contacts together, and the capacitor shorted. 
>>>> Of
>>>> course, the electrodes would have to be insulated from the solenoid.
>>>> Also, would it be possible to immerse this under oil, if the gap
>>>> provided by the solenoid was insufficient to prevent sparking over 
>>>> in
>>>> normal operation, or would the oil coat the electrodes and somehow
>>>> prevent safety discharge?
>>>>
>>>> Thanks,
>>>> Chris
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>