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Re: Contactor question

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 03:46 PM 8/14/2005, you wrote: 
Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi all,

Just a quick question about relay contactors. Let's say that I have
a 4-pole, 30 FLA inductive per pole rated contactor. Does this mean
that I will have up 120 amp inductive rating of the contact points if I
use all 4 of the poles in a parallel or series parallel fashion in a single
circuit to switch my pole pig transformer under a load?

Thanks,
David Rieben


yes sort of..

The problem is if you have them in parallel, and, you're flowing 100Amps, and you open the relay, and not all the contacts open at the same instant. The last set to open will be carrying the full current.

Practically speaking, though, it will work. The rating is mostly determined by the heating, which is a "slow" effect compared to the pitting from open/close.