Hello Ian,
What is a power factor correction? What is its purpose?
While looking for info about constant-voltage transformers I found a
thread
on this same mailing list dated May 2003. It said that classically, a
ferro-resonant transformer has a separate winding with a capacitor
across
it. The "bucking" winding as KA1XO said. However, the xformer I am
trying to
investigate has no separate "bucking" winding. The capacitor is wired
directly across the primary winding. It is a
500 V, 10 uF oil filled cap.
So I still do not know if I what I have is a ferro-resonant Xformer. I
will
check for air gaps, magnetic chokes and winding resistance.
Many thanks to all who answered my questions
and Vy 73 de Angel Vilaseca HB9SLV
"Ian White, G3SEK" wrote:
> Angel Vilaseca wrote:
> >
> >I am taking apart an old HV power supply made in the late '40s,
> >probably in Germany. From its size, the power transformer should be
> >rated for approximately 1 KW. It has an HV secondary winding 800-0-800
> >Volts and two 12 V for filaments. It has a vacuum rectifier.
> >
> >It has tuned chokes and I also found that a 10 uF cap is wired across
> >the primary winding of the power transformer.
> >
> >So I guess that this must be a tuned-primary power trnsformer. I never
> >saw this before. How does this work? What are the properties of a
> >tuned-primary power transformer? Does it prevent current inrush at
> >power-on like a tuned choke?
> >
> >Of course, I will replace the vacuum rectifier with solid-state diodes.
> >Should I leave the 10 uF cap acros ethe primary or remove it?
> >
>
> The capacitor is probably for power factor correction.
>
> There are a number of unusual things about this power supply, so you
> should be a little bit suspicious about the transformer.
>
> If you can, try to see if the core configuration looks normal - look
> particularly for any deliberate gaps or magnetic shunts. Measure the
> primary and secondary DC resistances to check if those appear normal
> too, as compared with similar transformers - a few tens of ohms for the
> secondary; a few ohms maximum for the primary.
>
> If you intend to use the whole secondary with a full-wave bridge and
> capacitor input (should give about 2kV on load), test the transformer
> with an existing power supply before you build it into a new one.
>
> --
> 73 from Ian G3SEK
> http://www.ifwtech.co.uk/g3sek
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