Re: From Member: using Digital Equipment Corp Transformers

Thanks to all for replying on the DEC transformers. For anyone interested
here's a link to the wiki, the ferro item is half way down on the page:
http://en.wikipedia.org/wiki/Voltage_regulator.
cheers
Denis

On Saturday 25 April 2009 08:30:50 Jon Elson wrote:
> Doug Pollard wrote:
> > dcassyc1 wrote:
> >> Hi All,
> >> I have a DEC power transformers which uses an oil filled capacitor on
> >> one of the windings, I suppose to provide Power Factor correction. The
> >> capacitor is missing and I don't know what value it should be.
> >> Is there a method I can use to determine the capacitor value?
> >> Is it possible to use this transformer without the capacitor?
> >> cheers,
> >> Denis
> >
> > I'm no expert on this stuff but I believe the only reason to use a
> > capcitor is to supply a jolt of electricity to something like a motor
> > that needs to start under a load.
>
> No, the "oil filled" capacitor he is talking about is clearly associated
> with a ferroresonant regulating transformer.
> We haven't seen stuff like this since the late 1960's, as they are
> expensive to make, heavy, and very inefficient, as part of the
> regulation scheme requires running a section of the iron at saturation,
> and due to hysteresis loss, the core runs hot.
>
> This is totally different from the usual DC power supply capacitors you
> are thinking of, which are connected after the rectifier, and would be
> electrolytic type instead of oil-paper type. The ferroresonant cap is
> connected directly to a special winding on the transformer.
>
> Jon