RE: [TCML] Terry filters

[resonance@xxxxxxxxxxxx]

Yes.  Due to high 26 kVA power level we used 12 AWG wire.  At 5-10 kVA
power level a good 16 or 18 AWG PVC covered wire is fine.   A bit of
resistance in using the smaller dia wire is good too as it adds a small
amount of resistance which further squishes the transients.

Dr. Resonance




> DC,
> I seem to remember you using and air core on the HV going out to Big
> Bruiser
> and the rotary. It was like 4"x30" wound with house wire? Is that about
> right?
>
> Thanks,
> Jim Mora
>
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
> Of resonance@xxxxxxxxxxxx
> Sent: Sunday, December 30, 2007 6:21 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Terry filters
>
>
>
>
>
> If you are really on a tight budget using used NSTs and can't afford a
> full Terry filter, there is an alternative.
>
> For almost 20 years I used a simple pair of air core RF choke made of 2"
> ID x 12 inch long PVC tube.  I wound it for 10 inches with #26 AWG PVC
> covered wire.  It seemed to catch especially the very nasty high freq
> transients that could break down the NSTs HV coils as these transients can
> form a "spider-web" like effect, essentially "crawling" over the windings
> until they connect and then the main power flows causes failure.
>
> Using a pair of these simple air core chokes I had only one failure in
> nearly 30 years.  Some of these coils with NSTs and these simple chokes
> are still in daily operation at museums for over 15 years.
>
> The failure I had was also a used NST so that could have entered into the
> factor --- the xmfr might have been ready for a failure from prior neon
> service.
>
> Food for thought anyway.
>
> Dr. Resonance
>
>
>
>
>> Hi Neal,
>>
>> Yes, there are losses with a Terry Filter. It is a trade off for
>> protection. It is also specific to center grounded transformers
>> primarily NST's due to their fragility. It is a one size fits all for
>> NST's for most of the components except the MOV's. When were using
>> MOT's, PT's, PIGs, etc.. there is no such filter added other than basic
>> mains filtering. Terry Filters are not a big loss, but there is some.
>>
>> The problem is that NST's can't handle to much voltage over their
>> ratings (were using NST's for something quite different then they were
>> designed). Most NST deaths are due to one of the secondary windings
>> being over-volted near the outer turns. NST's are also a pain in the but
>> to fix due to the potting compound. So a little protection does help
>> even with some minor filter losses.
>>
>> Take care,
>> Bart
>>
>>
>> Neal Namowicz wrote:
>>> Hello everyone,
>>> Just a question about terry filters, since the topic seems to be
>>> cropping up a lot lately. How much loss is there when using them? I'm
>>> no EE, but any time I see the main power coming in going through
>>> resistors, there must be some loss. Also, are the TF's "one size fits
>>> all", or can the components be sized to correspond with how much
>>> potential power you have coming in? It seems that we endeavor to
>>> eliminate "lossy" components. "Using beer bottle caps? Replace them
>>> with an MMC." Don't use a dimmer switch, too "lossy", etc. Ultimately,
>>> is using a TF a trade-off between loss and protection? Kind of like
>>> driving a newer car that comes with a mandatory explosive device (air
>>> bag) in the steering wheel. "But it's for your protection!" Just one
>>> of a number of reasons my two vehicles are 1964 and 1980 Chevys. The
>>> k.i.s.s. principle, and no bombs staring me in the face. But I
>>> digress, sorry. So, what do you think about the terry filters?
>>>
>>> Neal.
>>
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>
>
> Dr. Resonance
>
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Dr. Resonance

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