Re: PFC Question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

I was also surprised to read that. Say you want to
draw 30A at 240V, the ballast reactance is going to be
on the order of 5 ohms which is 26mH in a 60Hz system.
1mH is negligible compared to that.

But, imagine you're using an ungapped variac as the
ballast. Then the ballast inductance is several
Henries until it saturates at which point it's
effectively air cored. It will saturate early on in
each mains cycle: it must otherwise you wouldn't get
any significant power through. So most of the time it
is a few millihenries.

In this situation, adjusting either variac would make
a significant change in the effective ballast
inductance.


>  > This leakage inductance also explains why SRSG's
> need to be rephased
>  > as the variac output is brought  up.
>
> let`s see - 1mH in the primary it`s 1.6H in the
> secondary of my mot stack,
> it`s 4% of my charging inductance, so no -
> absolutely no any rephasing
> needed