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Re: PFC Question



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Dmitry,

I hope you're correct, however, the performance curves from powerstat may suggest otherwise. I'm having a hard time understanding how there can't be any series inductance when, say, the setting as at the midway point. Maybe you or someone else can explain this.

Gerry R.

Original poster: "Dmitry (father dest)" <dest@xxxxxxxxxxx>

you wanna say that if there`s a number of "toroid turns in series with
the load", then these turns  are "seen" by the load as some
inductance? it`s wrong too - variac isn`t an inductive divider, the
voltage on the load doesn`t depend from the current through it, so
load doesn`t "see" any series  inductance.

> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

> Hi Dmitry,

> YES, the mains see the variac inductance that is in parallel with the
> load. This inductance is very high however.  What I was trying to
> say, was when variac_out = variac_in, the wiper is at the power in
> point on the toroid so there are no toroid turns in series with the
> load for this case.  Hope that is clearer.

> Gerry R

>>Original poster: "Dmitry (father dest)" <dest@xxxxxxxxxxx>
>>
>> > Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>>
>> > PFC caps can also be placed upstream of the variac as well to
correct > for
>> > the inductance added by the variac itself.  However, the variac
>> > inductance will be a function of the variac setting (zero inductance
>> > when variac_out = variac_in)
>>
>>it`s wrong - when "variac_out = variac_in" the coil "sees" zero
>>inductance from the mains side, but the mains "sees" the full variac
>>inductance.


----- Neon transformers are doomed in Tesla service! I should know, I've killed more of 'em than many pople have ever even seen in a life time. 25-03-96 (c) Richard Hull, TCBOR