3-pole or 4-pole contactor

simone said:

Let's take the case that you have four one-phase circuits that you have to switch together. ¿Wich one of the following devices would you use?

1) A four-pole contactor, connecting each pole to one of the four circuits

2) A three-pole contactor, in order to switch the three phases, thus the four circuits downstream will be also switched

Dear Simone ;

As I understood, you have ” 4 Single Circuits ” and you want to switch ” On & Off ” together, if yes, you should define if these 4 circuits will be supplied by ” 3 phases + neutral ” or ” 1 pahse + neutral ” .

If the sypply is ” 1 phase + neutral “, you can choice a power contactor usning 2 of the main contacts to switch On & Off the supply, then the output of these 2 contacts will electrify the 4 circuits via ” 2 poles circuit breaker ” for each circuit. Noting the the nominal current of contactor should be equal or bigger than the total current value of these 4 circuits.

If the supply is ” 3 phase + neutral “, you can choice a 4P power contactor usning the main contacts to switch On & Off the ” 3 phase + neutral supply “, then the output of this contactor will electrify the 4 circuits via ” 2 poles circuit breakers ” for each circuit. Noting the nominal current for contactor should be the current value for 2 circuits, because you have 2 circuits on the same phase.

Regards.