Mag Starter - Sanity Check - Nema Square D 8536sbg2s

[Brian Holcombe]

On this starter, is it typically that both coil leads should receive 120v power? It seems typical that only one side of the coil receives 120v via the start switch and the other side goes to an override?

[Bill Dufour]

One side of coil is direct return to neutral. its just like a light bulb power in one wire, power out the other. Start switch bypasses any relays and sends power direct to the coil input. When the relay latches closed it takes over and supplies power to that same terminal on the coil. A contactor will close and run the motor as long as the start button is held down, even with a bad stop switch
Bil lD

[Matt Mattingley]

One side of coil is direct return to neutral. its just like a light bulb power in one wire, power out the other. Start switch bypasses any relays and sends power direct to the coil input. When the relay latches closed it takes over and supplies power to that same terminal on the coil. A contactor will close and run the motor as long as the start button is held down, even with a bad stop switch
Bil lD

in most three wire control situations there will be a jumper to the electro magnet, which is always hot. To complete the circuit the stop button (which is normally closed, NC) transfers power to the start button. A bad stop switch with open contacts should never allow a machine to start. This is just my opinion.

Sure, if you add 120 v to one side of the coil and a alternate 120 v to the other side of the coil, this would have a complete circuit of 240 V. if either of the legs were dropped, it would be in incomplete circuit, And nothing would happen.

[Brian Holcombe]

Thanks fellas.

[Bill Dufour]

https://www.theautomationstore.com/c...-stop-circuit/