Re: Xfrmr shunt theory

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Peter,

I would take out laminations before I would play with air gaps.  Lamination
packs do often have their own air gaps in the pack of laminations but I
assume the maker knew what they were doing.  

The real way to adjust the NST for high power is to sort the outputs with
an ammeter and take out or adjust the packs until the current you want is
reached.  Us a variac to bring the voltage up slowly.  Incase it is not
right, you can catch it before doing damage.  Since the output is shorted,
high voltage is not an issue.  However, be extremely carful in any case...

Cheers,

	Terry


At 12:07 PM 5/4/2001 -0700, you wrote:
>Terry,
>      I have a 7.5-30 and a 9-30 NSTs that I have de-potted.
>      
>The 7.5 has two shunts (which are stacks of lams) which don't quite completely
>fill the gap, and in fact one of the stacks is one lam short and has a larger
>gap than the other. Is this by design, or a manufacturing defect.
>
>The 9-30 has 2 shunts (which are stacks of lams) that are stacked the other
>way, if I leave some out the rest of them will still completely cross the gap
>between the legs of the "E".
>
>What would be the difference in operation, will one of them not have the
>"linear" current limiting that NSTs are known for, when the shuntage is
>decreased? Will there be some other kind of difference?
>
>-Peter Lawrence.
>
>
>>Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>>
>>Hi Peter,
>>
>>Shunts are usually made of many metal plates and you can easily take a few
>>plates out.  So #1 is by far the best.  Air gaps have a very extreme effect
>>and it would be very hard to adjust NSTs with air gaps.  Definitely #1 is
>>best.  Some current limited transformers meant for very low current do use
>>air gaps but those are very carefully made.  A little filing in such a case
>>may do the trick.  However, almost all NSTs will use plates and not air gaps.
>>
>>Cheers,
>>
>>	Terry
>>
>>
>>At 10:45 AM 5/4/2001 -0700, you wrote:
>>>
>>>I've gotten zero response in a week, I'll try asking one more time...
>>>
>>>
>>>Xfrmr Folks,
>>>            seems to me there are two ways to decrease the shunt-age in an
>>>NST.  1) remove something so that the shunts have a smaller cross
section but
>>>still bridge completely across, 2) remove something so that there is an air-
>>>gap to the shunts but they still have their original cross section.
>>>
>>>Which is prefered and why.
>>>
>>>
>>>Thanks,
>>>-Peter Lawrence.
>>>
>>>
>>>(another Q, has anyone ever tryed to "increase" the shuntage in a MOT to
>>>lower the current and make it usable with a static gap?)
>>>
>>
>>
>