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Re: [Amps] 3 phase transformers on single phase - advice pls?

To: "Keith E. Spainhour" <KSpainhour@wilkes.net>, <amps@contesting.com>
Subject: Re: [Amps] 3 phase transformers on single phase - advice pls?
From: "Carl" <km1h@jeremy.mv.com>
Date: Mon, 17 Nov 2008 23:16:34 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Multi purpose industrial xfmrs are rather easy to find at scrap dealers 
and surplus stores.

I use a pair of 5KVA Westinghouse  240 to 480V units to feed the garage 
and step down again. Cuts losses in half in the 150' run of 10/3. In 
your case you will need to find a 460V motor for a rotary phase 
converter, that may be very expensive even on the surplus market as that 
usually means 25 hp or more.

Best bet, return the cutter and buy something compatible.

Carl
KM1H


----- Original Message ----- 
From: "Keith E. Spainhour" <KSpainhour@wilkes.net>
To: <amps@contesting.com>
Sent: Monday, November 17, 2008 9:08 PM
Subject: Re: [Amps] 3 phase transformers on single phase - advice pls?


> Hello,
> This question could not have come at a better time. I am currently 
> trying to
> do the same thing with a plasma cutter I purchased this weekend. It 
> turns
> out the unit I thought was 220v single phase was actually 460v 3 
> phase. The
> transformers are the same 3 bobbin type. I found this page that 
> explains
> some of it, but I am still trying to find the best way to run these
> transformers from 220v single phase.
>
> http://www.basler.com/downloads/3phXfmrs.pdf
>
> Take Care,
> Keith Spainhour, KT4XW
>
>
>> I'm sure I should know the answer to this, but just can't seem to 
>> find
>> anything in my literature or on the web. A friend (G7ODR, cc'd on 
>> this
>> email) and I have scratched our heads, but the more we discuss the
>> problem, the more complex it becomes.....
>>
>> If I use a 3 phase transformer (either a 380v or 415v primary) on a 
>> 240v
>> single phase power supply, then what will happen in the secondaries?
>>
>> I think the transformers that I have access to are delta input and 
>> star
>> output. They're open 3-bobbin jobs rather than potted or enclosed.
>>
>> Can I wind the secondaries in series without overloading the 
>> insulation?
>> Could I wind them in parallel? Would I hit core saturation problems?
>>
>> So, to put a few figures on it, if it's a 12kva 3 phase 380v in, 6kv 
>> out,
>> what would happen with the various permutations if I try to wire it 
>> onto
>> 240v single phase?
>>
>> I'm actually looking for 4.5kv RMS out at 10kva and can get a single 
>> phase
>> one custom wound, but at a price (£950 from TEC). Anyone in the UK 
>> know of
>> a cheaper but quality source?
>>
>> Phone a friend, ask the audience etc.... ;-)
>>
>> Any ideas appreciated.
>>
>> cheers
>>
>> Dave G0OIL / K2MOO
>>
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>
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