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440 to 220 Conversion

1943Monarch

Plastic
Joined
Jan 22, 2021
Of course a coil and heaters for 220 volt operation are rarer than hen’s teeth. Rather than just buying a new contactor with a thermal overload relay, I took the following approach:

Coil
Convert 220 volts to 440 volts using the center topped primary of a 480/240 to 120 volt, 50 VA transformer (like an auto transformer).

Thermal Overload
Buy a new, adjustable thermal overload relay with an automatic reset to replace the original.

Start Button Lamp
Use the 120 volt secondary to power a 120 vac LED pilot light.

Total cost was around $100.
 

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You can operate a 480V coil on 240 by connecting a capacitor in series. The capacitor cancels part of the impedance of the coil, making it draw more current. I have a 3hp dust collector that has a 9 wire motor, so no problem there, but a 480V coil on the starter. It has run for many years with a 2 mfd oil filled one capacitor.

Bill
 
I'm converting a '67 Monarch 612 from 440 to 220, pretty much the same thing, two thermal overload relays from WolfAutomation for about $30 ea including the mounting bracket (since I'm not replacing the old Westinghouse contactors). The transformer just needed to have a few leads swapped, primary in series instead of parallel, all of the switch/coil circuits in this one are 120V. Happily the overload relays are for the pump and traverse motor, converting the main motor from 20HP to 10HP (using the 20HP as an RPC idler) means that heater was re-usable.
 
You can operate a 480V coil on 240 by connecting a capacitor in series. The capacitor cancels part of the impedance of the coil, making it draw more current. I have a 3hp dust collector that has a 9 wire motor, so no problem there, but a 480V coil on the starter. It has run for many years with a 2 mfd oil filled one capacitor.

Bill

Thanks for the advice. That would have been a better solution.
 








 
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