What is the coil on the main contactor supposed to be? 1977 Modular Drive

TheOldCar · Jul 15, 2020

Ugh.
I'm an idiot.
You can set the wires to 120V or 240V on the coil of main contactor, labeled "PC". Since mine was missing, I installed a Square D size 0, just a single phase one after the 3 phase pump motor starter. WHICH setting should it be?

Did I mention I'm frustrated with my electrical stupidity?

Monarch sent me the schematic AND wiring diagram, but diagram doesn't show actual wires.

TDegenhart · Jul 15, 2020

Best way is to measure the voltage at the wires that go to the coil. Next way is to trace the wiring to devices and note how they are connected. wire two 120 volt light bulbs in series and note the brightness. Wire the coil for 240 and observe how smoothly it operates. How is the new contactor connected with the pump motor. Note there is no 3 phase 120 volt.

Tom

TheOldCar · Jul 15, 2020

New contactor takes L1 and L3 from the pump contactor (which, by the way is a size 1 but only size 00 supposed to be there).
I have been inventive (read:stupid) enough to hook the coil both ways. 120 and fan & light turn on. 240 and neither.

Both ways motor runs if I force fwd/rev contactors.

Holy freak it’s humbling to not understand electrical systems despite the repair I do at work.

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What is the coil on the main contactor supposed to be? 1977 Modular Drive

TheOldCar

Stainless

TDegenhart

Diamond

TheOldCar

Stainless

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