WAY OT! Re: [SEL] Early Switchboard Meters and Switchgear

[Listerdiesel]

On 7/18/05, Curt <curt at imc-group.com> wrote:
> John,
> Since you have changed from DC circuits to AC circuits,  I gotta ask,
> why use a solid state device for energy absorption when a simple rugged
> RC circuit does well?
> I've not seen these quenching/spike diodes you mention used anywhere on
> contacts or coils. Are these simply zenors?
> On your tubes.....5Y3GT 's? I think I've still got a few of those.....
> Curt Holland
> Gastonia, NC

There are practical limits, especially on voltage, for discrete surge
suppression devices. Diodes and RC snubbers are great at low voltage,
we use RC snubbers on our thyristor stacks, but at high voltage with
inductive loads, you cannot beat an arc chute type circuit switch.

Magnetic arc blowouts are also quite common.

ABB in France still make old-fashioned clapper contact switches, and
we use them in the big high voltage battery charges.

Peter
-- 
Peter A Forbes
Email: listerdiesel at gmail.com
Web: www.oldengine.org/members/diesel