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Re: Xfrmr shunt theory
Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>
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?
>Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>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.
>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...
>> 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.
>>(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?)