Re: Contactor question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jerry Chamkis by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jchamkis-at-bga-dot-com>

You'll definitely increase the life of the contacts with a 'snubber' across
each individual pair of contacts.  Each snubber consists of a series
connected R - C network.  There are optimum values for a given inductance and
current draw, but those probably assume better-behaved loads.  I'd start with
a .05 uFd cap (at 1 Kv at least- because I'm the paranoid type- and remember,
you're suppressing an ARC) in series with 100 ohms or so at 1 or 2 watts.
Remember there is going to be leakage current through the capacitor when the
contactor is open so be -extra- careful about shock hazards.

Cheers-

Jerry

On Wednesday 25 June 2003 11:46 am, Tesla list wrote:
 > Original poster: "Richard W. by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > <potluck-at-xmission-dot-com>
 >
 > Hey List,
 >
 > Scenerio:
 > Variac stack feeding a 10Kva pig 240vac at 35 amps.
 > 2 poles on the contactor are being used (red and black wires)
 >
 > Contactor
 > Arrow Hart Size 3
 > 240v 25hp 1 phase
 > 120 FLA
 > 720 LRA
 >
 > Under the above conditions the contactor opens....
 > Do I need some kind of arc protection and if so how?
 >
 > Thanks

-- 
Jerry Chamkis
jchamkis-at-bga-dot-com