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RE: [TCML] Bypass Capacitor



Hi Gary,

Yes, I was aware of the RC impedance but hadn't thought of parallel gap
stresses. Maybe I'll just re-shelve the TDK's for another project though
they are UHV-9AT's.

Jim Mora

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Lau, Gary
Sent: Tuesday, December 23, 2008 4:50 AM
To: Tesla Coil Mailing List
Subject: RE: [TCML] Bypass Capacitor

The resistors in the Terry filter perform an important function.  The R's
and C's form an R-C low pass filter, which works much better if you have the
R's (although having just the C's will still attenuate some high frequencies
- just not as well).

But more importantly, the R's limit the discharge current through the C's.
Without the R's, the bypass caps are directly in parallel with the main gap.
Every time the gap fires, the charge in the bypass caps is directly shorted
out by the gap - pretty stressful for the bypass caps.

I don't know if pole pigs and PT's actually benefit from Terry filters, but
the bypass caps will clearly benefit from the use of resistors.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Jim Mora
> Sent: Monday, December 22, 2008 11:15 PM
> To: 'Tesla Coil Mailing List'
> Subject: [TCML] Bypass Capacitor
>
> Hello All,
>
> I have decided to put my 5KVA pushed to 7500, 15kv Potential transformer
in
> a transformer cabinet per Dr. R's advice and ground one side to RF ground.
> The transformer will have a Joslyn 17KV protection gap from hot to ground.
> Hopefully, it won't fire in this range. GE said grounding either side
would
> be fine.
>
> Here's the question: I am thinking of using (3) or (4)  2nF caps in series
> to ground as a RF bypass along side the Joslyn. They are 40KV TDK's. A
> 500Mohm bleeder string using 2 watt resistors per cap will be applied. The
> gap is a rotor type and there will be a horn gap on that end. Has anyone
> tried this type of configuration? It is basically a Terry Filter sans
MOV's
> and resistors and a lower Cap value.
>
> This is a NICE transformer and I want to protect it.
>
> Thoughts?
>
> Jim Mora

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