Converting to single phase

[ajtoady]

I'll take a look at some of my books and see if I have a generic wiring diagram. If I do i will post it here.

 

[Wookie]

This web page Motor Starter Wiring Diagrams - VintageMachinery.org Knowledge Base (Wiki) has diagrams for a 3 pole starter and a single phase motor. It looks to me like they are breaking neutral and just using a single wild leg, which is not what you want, but anyway, here are diagrams.

 

[abyss_scuba]

Thanks guys. Maybe I did not explain it right. This compressor comes either 3 phase or single phase. The box where the wiring comes in from the disconnect has two wiring plans for either single or three phase so I thought if the wires were arranged as shown it would start right up. If I push the center bar the motor starts right up. I think the problem is the starter relay which is not engaging. Btw I believe the relay was always 120.

 

[Wookie]

Measure the continuity across the coil. If it's open, get a new coil. I believe you either have a burnt coil or a wrong voltage coil. The fact that your compressor picks up manually tells me that the mains are wired correctly. Can you post a picture of the starter showing the wires from the starter to the coil? Most 3 phase starter coils are 240v, most single phase coils are 120V. The coil itself will tell you what the voltage should be.

 

[abyss_scuba]

Success seems we missed moving a relay wire. On 3 phase the relay goes to L2 which is the center post on a single phase L2 is the right post. I missed the most simple answer, human error. Back in business now to button it up and fill tanks. Just in time too as I was on my last full set of tanks for class. Woohoo. Again thanks for all the ideas.

 

[NAM001]

From working things like this. when you have 3 phase often 2 of the legs are used to get 120vac to power the control circuit. if you moved the wireing then you hmay now be using 2 hot lines to power th motr but the control circuit is with out power cause it is still wired to a now unused wire.. send me a eail with the schmetics of both 3 and single phase wireing.

Thanks guys. Maybe I did not explain it right. This compressor comes either 3 phase or single phase. The box where the wiring comes in from the disconnect has two wiring plans for either single or three phase so I thought if the wires were arranged as shown it would start right up. If I push the center bar the motor starts right up. I think the problem is the starter relay which is not engaging. Btw I believe the relay was always 120.