Help with motor capacitor wiring

Dangerous assumption. Check with a meter first, see what continuity there is.

4 REAL hp would pretty much force it to be a 240 volt motor. IF so, the 1+2 and 3+4 will pretty much fry > Picked up a "2.98 kW" (4 HP?) 60 gallon Speedaire compressor with a

Yes.

I am thinking.

Terminal one (hot) has one fork. Terminal four (hot) has two forks. Terminal two has one fork. Terminal three has two forks.

i

Pictures of the motor and connection box are here:

A search on the Dayton MC-261 motor has a couple threads that state it is a single phase non reversible motor that use only pins 1 & 4 for the 240 VAC line. It has two capacitors from the photos. Have you tested or replaced them?

Not yet. If only two terminals are used (1 and 4), then why are these terminals 2 and 3?

I will get the cap out tonight, hopefully, and will replace it in any case.

i

Looking at the photos, I'd expect continuity between 3 and 4 and also between 1 and 2.

One direction would be 3 jumpered to 1 and 4 jumpered to 2. Other direction would be 3 jumpered to 2 and 4 jumpered to 1.

But I could be wrong.

they reused an existing part from a different motor because it fit and didn't have pay more design fees.

It's nameplate rated as a 230V machine (not 115/230) So 1 and 4 are line input. 2 and 3 must be the series connection of the start winding, the capacitor and the centrifugal switch.

To double check - there should be continuity between 1 and 4; but 2 and 3 both open circuit to everything else

1+2 and 3+4 for forward 1+3 and 2+4 for reverse

If it's not obviously burnt the switch or the capacitor are likely suspects. Connect 1 and 4 only and rope start it to check that the main winding is OK

Jim

There is no reason to assume that any connections need to be made, other than the connections shown/mentioned on the motor data label. That means earth ground too.

Dayton, or a Dayton motor distributor, may/should be able to supply a diagram for the internal connections (centrifugal, thermal protect switches and capacitor connections).

You should be completely familiar with the troubleshooting procedures by now. Initial live checks are easier to interpret, and likely safer, with the pump belt removed.

See Roy's and others' recent recommendations for Dave's compressor motor which wouldn't start.

-- WB .........

Jim.. Thanks... You are the God of electric motors... I will try to do more tonight, hopefuly before the McMaster order cutoff time, so that I can order an appropriate start cap.

One has to wonder, however, why 1 and 2 has only one terminal blade.

i

OK, that could be.

i

Dayton is owned by Grainger's

Probably not. I am guessing it is a dual-voltage motor, and likely you tie 2-3 and tape up for high voltage, and probably something like line in on 1-2 and 3-4 for low voltage. But, it could be a reverisble motor. Usually, reversible motors do not have 4 leads, but have a terminal board insde where you reverse two wires to change the direction. Is there a nameplate? If not, there might be a paper label somewhere under a cover with the wiring instructions.

Jon

it is not

There is a nameplate:

it says connect to terminals 1 and 4 only. But maybe 2 and 3 were connected somehow in the motor as it was shipped, but now they are not connected to anything as of now.

I know that it is 230v only, and nowhere it mentions that it is reversible.

i

Also, possibly, 2 and 3 are for external operation of the safety thermal reset that is built in the motor.

:

Look closely at the terminals. Use a magnifying glass. Do they all show signs of use?

Paul

I've never seen it mentioned on a motor - and I've never seen a non reversible motor (except really small ones). Who would build a motor in two versions, clockwise and anti-clockwise?

I'm 90% sure there were jumpers inside as shipped.

Did you look at the photos? It is a motor designed for air compressors. Why would you want to reverse one?