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three phase selector switch wiring help

niterider40

Plastic
Joined
Jun 28, 2020
I cant seem to figure out what posts the hand/auto wires go to on this furnas three phase magnetic starter with pressure switch I think the wires that are connected in the pic are ok, I just need to figure out where the wires go that arent connected. This is for a 25 hp quincy air compressor powered by a 15kw military generator.
 

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Well, that's an oldie-but-a-goodie.

Tying the "V" terminal to neutral or to another phase (depending entirely on the coil voltage - which by the way, don't be so stingy and share it with us please) should pull that sucker in.

I'm guessing that based on the age, and how the jumper bars are installed, we are looking at a 240 VAC coil. If that is the case, then it needs to be connected phase to phase for 208 - 240 three phase.
 
This is a FURNAS Part number D71221-32 Dual voltage coil 60 Hz 208-240V, 50 Hz 190-220V, 25... 115V and 60 Hz 440-480v, 50 hZ 380-440v, 25...230V. The wires are set up and the relays for the higher voltage as it is to run a 3 phase motor on an air compressor. The magnetic starter is wired with a selector switch as Auto-(Pressure)- OFF- Hand (manual) with contacts as normally open. The pressure switch is normally closed. I am having trouble wiring in the switch/starter. I am not sure which screw on the relays that I should be tightening, V or W. I believe it should be wired as L1 to the off on the selector switch which controls the pressure switch on the auto side. The Hand (manual) and the load side of the auto switch should go to the coil, after that I am confused as to where the L2 and thermal overload relay are in the box to complete the circuit to start the magnetic coil.
 








 
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