Re: Wiring two 15KV 240V/50Hz Transformers in Series for use with 110V (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 16 Jun 2007 08:48:23 +0800
From: westland <westland@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Wiring two 15KV 240V/50Hz Transformers in Series for use with 110V
    (fwd)

Gary:

Thanks so much for the insight.  I would never have known this.  Is 
there a particular reason for having a tap in the middle of the secondary?

I suppose I could grab 230v off of the mains, but my setup is less than 
1KVA, so I probably will just buy a step up transformer here (they are 
much cheaper here) and put it in with the transformers.  Or maybe just 
buy some new transformers when I'm in the US

Thanks again

Chris

Tesla list wrote:
> ---------- Forwarded message ----------
> Date: Fri, 15 Jun 2007 09:42:34 -0400
> From: "Lau, Gary" <Gary.Lau@xxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: RE: Wiring two 15KV 240V/50Hz Transformers in Series for use with 110V
>     (fwd)
>
> Hi Chris:
>
> Sorry, but you can't do what you propose.  15kV NST's are made with the
> secondary midpoint connected to the case.  If you connect the
> secondaries in series, the two cases will have 15kV between them.  The
> primary-to-case insulation is not designed to sustain that and will
> fail.
>
> Most US households have 240V available in the breaker box to power
> electric stoves, dryers, and other large appliances.  You'll have to use
> the NST's at their rated input voltage.  If you're in an apartment that
> doesn't have 240V available, your only alternative is to get a 120/240
> step-up xfmr.
>
> Regards, Gary Lau
> MA, USA
>
>
>   
>> Date: Fri, 15 Jun 2007 14:10:05 +0800
>> From: westland <westland@xxxxxx>
>> To: Tesla list <tesla@xxxxxxxxxx>
>> Subject: Wiring two 15KV 240V/50Hz Transformers in Series for use with
>>     
> 110V
>   
>> I have an interesting variant on one of the questions that just came
>>     
> up
>   
>> about series wiring of transformers.  I'll be moving to Chicago in two
>> months, and from 220V to 110V mains.  I currently have two 15KV
>> 240V/50Hz/0.03A Transformers wired in parallel (for .060A) that power
>>     
> my
>   
>> TC.  I'm wondering if there is any problem switching leads around for
>> 110V/60Hz ... running the secondary in series, and the primaries in
>> parallel.  I figure since its a 50Hz transformer, it's already about
>>     
> 20%
>   
>> overengineered, and the secondaries takes 15KV at .03A, so I should
>>     
> end
>   
>> up with output of 15KV at .03A (rather than the 0.03A I get in Hong
>>     
> Kong).
>   
>> I'm looking for a sanity check on my logic, just to make sure that I
>> don't bring them to the States only to burn them up.  Clearly, I can
>> keep the current arrangement, and just precede them with a 110 to 220V
>> stepup transformer.
>>
>> Chris Westland
>>
>> --
>>
>> ___________________________________________________
>>
>> J. Christopher Westland, PhD CPA
>> Professor, ISMT, University of Science & Technology, HK Clearwater
>>     
> Bay,Kowloon,
>   
>> Hong Kong
>> Tel: 852 2358 7643
>> Fax: 852 2358 2421
>> Mob: 852 9528 1745
>> URL: ihome.ust.hk/~westland
>> Mobile e-mail: chris.westland@xxxxxxxxxxxx
>>
>>
>>     
>
>
>
>   


-- 
____________________________________________________

J. Christopher Westland, PhD CPA
Professor, ISMT, University of Science & Technology, HK Clearwater Bay,Kowloon, Hong Kong
Tel: 852 2358 7643
Fax: 852 2358 2421
Mob: 852 9528 1745
URL: ihome.ust.hk/~westland
Mobile e-mail: chris.westland@xxxxxxxxxxxx