yes, as you see there is a part beside its contacts and as far as I got it was a big magnet which creates a force to open the contacts, what I cant understand is why is this guy so big? It is an old technology to what seems but for a current like 400 Amper how can be modern guys(contactors) more little? Or are they still as big as this one?
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The magnetic force will close the contacts, not open them.
These old timers needed a lot of physical travel to extinguish the arc in the arc chute. With three poles, it is probably for AC use.
Never contactors with double break and de-ion plates are able to interrupt the current with much less separation and less physical travel.
Bill
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"Why not the best?"
Jimmy Carter
Those old-time contactors are still made and although they're expensive and clunky they are great for very heavy starting or plugging duty, and there are variants for DC where they are still the norm for DC switching over about 100A and 200V.
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