[Prev][Next][Index][Thread]
Re: Ballasting ..... Again
In a message dated 98-10-23 00:22:45 EDT, you write:
<<
> I also noted with *great interest* the comments suggesting no difference in
> performance with slotted vs non-slotted cores - obviously not having to cut
> the core would save a lot of effort.
> Cheers,
> Mark
>>
Mark,
I've never slotted a variac core yet, but I know the unslotted cores can
waste half the power into the system, can saturate, and cause other
problems. When the core is slotted, the variac will have less inductance,
but will not saturate. So it's necessary if make sure the variac will still
have enough inductance after the core is slotted. Use a large enough
variac, or use an additional fixed inductor in series with the variac. This
could be switched in or out to change the range.
Those who saw no improvement after cutting the slot may have
experienced the result of the drop in inductance from the slotting
procedure. The slotting will not improve the current limiting, it will
actually give less current limiting. The slotting is important for
preventing saturation however, and the drop in inductance is a
necessary tradeoff, thus the need for a larger variac if it's slotted.
This is my present understanding of the matter, based on my
limited experience in the area, and from reading various posts.
There seems to be such controversy in the ballasting area. I do
like to get the true facts in these issues.
John Freau