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RE: Ballasting the secondary side of transformers



Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Hello All,

Capacitive reactance is effectively greater on the HV side yes? Quoting Bert
Hickman from 2002:

"Original poster: "Bert Hickman by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

When used on the LV side, capacitive ballasting may not work nearly as
well as inductive ballasting. It also gives you a leading power factor
(current leads voltage) which may cause problems elsewhere in your
home's power distribution system.

Where capacitive current limiting really seems to pay off is in the HV
side in DC coils that use the voltage doubling circuit originated by
Marco and discussed by Greg in a recent posting (See the "How to tame a
Wild MOT" thread).

Best regards,

-- Bert --
--
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Friday, April 06, 2007 10:53 PM
To: tesla@xxxxxxxxxx
Subject: Re: Ballasting the secondary side of transformers

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

Hi Bart,

Ballasting on either side should be equally effective at limiting the
current.  Of course, on the HV side, the inductance value needs to be
the turns_ratio (n) squared times larger because it has n times the
voltage to deal with and needs to limit the current to 1/n times the
current on the primary.  This assumes an ideal transformer between
the LV and HV ballast points.

LV ballasting:      + smaller inductance needed, lower voltage stresses.
                           - larger current means larger guage.
                           - core is needed to get the inductance and
saturation needs to be considered.

HV ballasting:      + smaller current.
                           - HV insulation needs to be considered.
                           - inductance needs to be n^2 larger.
                           - core is needed to get this larger
inductance and saturation needs to be considered.

These are all of the plusses and minuses that I could think of.  If
others, maybe someone else could chime in and comment on what is said.

Gerry R.


>Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
>
>Can someone please tell me why we are still ballasting on the LV
>side of Pigs and PT's? This should be easy enough to do for a fixed
>current limit. The costs associated with a LV ballast almost demands
>we do this. The LV side is starting to appear very silly to me at
>the moment. Granted, there are HV concerns, but is it really a big
>deal? I get the feeling LV ballasting is simply convenient. However,
>it is also expensive (unless one builds a ferrite ballast).
>
>Just curious is anyone else has contemplated a high side ballast.
>
>Take care,
>Bart
>
>Tesla list wrote: