24V Coil Packard Contactor

Korishan

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I think "Definite Purpose" refers to the special use case of a contactor which is switching large loads on and off. This is just what they are called, they are DP contactors instead of general purpose contactors, if there is such a thing, or general purpose relays.

Contactors, by design, are usually normally open. Unlike relays which often have NO and NC contacts. You have to apply the control voltage to the coil to close the contacts. When the coil is de-energized the contacts return to their NO state, usually by spring force.
 
Ahhh, ok. thanks. So to use this with a 48V setup, could you use 2 of them with the coils in series to split the 48V into 2x24V loads in the coils? The logic here would be, one it'd be more efficient (i'm guessing than bucking the voltage to 24V) and if one of the coils failed for what ever reason or there was a trigger of some sort, "both" coils would disengage at the same time.



Here's what I'm thinking:

Battery -> Contactors -> Inverter
The contactors are controlled by the BMS. If the BMS detects a fault, it could disengage the contactors. The contactors could be powered through a relay that is controlled directly from the BMS, unless using a FET would be a better option. It should be low current.
 
I guess you could do it but I'm not sure if it's a good idea. I don't know about the specs of the contactors regarding 24/7 operation and opening only on a fault which might never happen. Contactors are made to switch on and off large loads remotely so you don't have to waste large amounts of copper and energy by transferring high currents over long distances.

Typical example of a use case for a contactor for personal use would be an air compressor in your workshop or some other form of a big electric motor. To reduce the noise you've put the compressor somewhere where it doesn't bother you too much, maybe in another room / behind a wall / outside. To turn it on and off you could go there and flick a switch or use long and thick enough cables to switch it on while standing at your workbench. Or you could use a contactor that can be operated remotely with low voltage and low currents to switch the high voltage and/or high current side.
 
I aggree with Darkraven, a contactor will fail when activated 24/7 for weeks or even months... the contacts need to be "slammed" together ever so often to make a decent contact again, and not stick together.
The coil might overheat also, this depends on the quality of the contactor, but i would not be trusting a ebay contactor.


The contactor in the link you posted, has a 24VAC coil, ( i read 24V50-60Hz in the discription ... so AC i beleave)

You will be better of with a latching relais, or even better, a breaker with shunt trip of a good and known brand, then you have also the "fuse" funktion.
 
Ok, thnx. That clears up the murky water a bit :)
 
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