Re: [TCML] Series/parallel potential transformers

[Mark X2 <susax2@xxxxxxxxx>]

2013/4/5 Jim Lux <jimlux@xxxxxxxxxxxxx>

> On 4/5/13 9:26 AM, Mark X2 wrote:
>
>> Hi all,
>>
>> I've got two 6kV double pole PTs and I'd like to put the LV windings in
>> series and the HV windings parallel, to get rid of the otherwise needed
>> 230-110V transformer.
>> The thing is that they're not identical. The old one's HV winding has 2,1
>> kOhm resistance and the newer one 2,6 kOhm.
>> I'm not sure if I can get away with this or should take certain measures?
>>
>>  don't see why it wouldn't work.  The resistance difference could be
> something like one is wound with aluminum and the other copper, or with
> different gauge wire.
>
>
> Easy to test.. hook up your 220V (or 110V) to the high voltage windings
> and measure the voltage on the low voltage windings.   This is also a good
> way to check the phasing after you connect them together..
>
> (although if it's marked with the usual X1/X2 and H1/H2, that's probably
> not needed)
>



 Thanks Jim,

had the paralleling variac thing still in mind that kept me doubting.
(glad I decided back then to use bifilar wire for the ballast..)

I hooked them up now just before reading your reply. Checked phasing by
applying 1V and it measured 60V the first try, so same trick the other way
around.

Those markings, where's the DIN when you need it...
One has u-v U-V, the other one a-b A-B and the single poles have u-x U-X
e-n or d-a da-dn.
Can be confusing sometimes without proper documentation.

They're both Ritz / TuR, the older ones are more overdimensioned as it
seems, both bigger and heavier Guess it's the same trend as MOTs and stuff
have gone through.

A while ago I managed to demolish a really old 6kV "Hedgehog", so I took
the core out and milled a quarter of the resin away to find out what's
inside. The LV winding was flat 4x1mm aluminium ribbon with paper/cloth
insulation and the HV winding an 0,32mm enameled copper wire. Between each
layer there's a film of resin applied, so very good insulated, but nothing
to salvage.
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