Do I Need A Magnetic Motor Starter?

Normally a contactor is wired with a momentary switch and an auxiliary contact in parallel to latch the circuit on. You can also wire a on/off switch directly to the coil, with no auxiliary contacts. That configuration doesn't protect against restarting after power loss/restoration.

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pstemari said:
Normally a contactor is wired with a momentary switch and an auxiliary contact in parallel to latch the circuit on. You can also wire a on/off switch directly to the coil, with no auxiliary contacts. That configuration doesn't protect against restarting after power loss/restoration.

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Exactly. In basic motor control there is what’s called 2 wire control and 3 wire control. Typically 2 wire control is a maintained switch that will turn on the starter. If the starter loses power the switch is still closed so when power is restored the starter energizes. 3 wire control uses momentary contacts and a holding contact on the starter to energize it. Therefore if you lose power the starter won’t turn back on units you push the start button.


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Some starters employ very simple VFD technology, they will start an unloaded motor slowly with a low starting current and a smooth ramp up speed rather then the all or nothing approach that a simple contactor employs, they cost considerably more however. Often called a Soft Start by electricians.

Soft start pneumatic valves are often used in distributed pneumatic control systems in order to keep many of the actuators from operating wildly upon start up, these are also not inexpensive.

Buy what works for you in a particular situation.
 
BTW. I have a 120v magnetic starter for sale if you or anyone else needs one.
Robert
 
If you find 2 outlets where the small holes do not have continuity between two outlets you can pair them for 220v single phase.
 
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