3-wire submersible pump controller specs

[Robert Scott]

25 years ago I bought and installed a Sears 3-wire well pump and controller. It is 1/2 HP and made for 230 VAC. Lately the controller has been acting up, making buzzing noises, etc. So I decided to replace it. I bought the latest 1/2 HP pump controller from Sears, but I don?t know if it is right for my pump. The specs are off and there are some other differences.

The original pump controller advises that the winding resistances for the pump motor should be:

Red to Yellow: 5.2 Ohms (the Start winding) Black to Yellow: 4.0 Ohms (the Run winding)

And sure enough, when I measure my pump with the power disconnectedf, my pump is very close to these measurements. But the specs on the new pump controller call for:

Red to Yellow: 18.5 Ohms (the Start winding) Black to Yellow: 4.7 Ohms (the Run winding)

The Run winding is close enough, but the Start winding is way off. Also, the original controller has two capacitors: a Run capacitor and a Start capacitor. The new controller has only a Start capacitor, which I measured to be 62 uF. Both controllers have a relay to switch the windings and the capacitor, but I find it hard to believe that a pump designed for a running capacitor can run just fine without one, and the big difference on the Start winding specs has me worried.

Before I replace the controller and risk burning out my pump, I would like to know if anyone can shed any light on these differences.

Robert Scott Ypsilanti, Michigan

[lee houston]

See if you can find the specs for the latest pump this new controller is sold for. Sounds like changes in the pump. If so the new controller is of no use at all. that's a dramatic change in the start winding resistance.

Likely a good approach would be to repair your old controller. Capacitors do go bad with age. Is there any ooze leaking from the caps? If you don't know how to test caps with a meter, take controller to a radio tv shop for testing.

Can you run the pump with the controller parts accessible? Where is the buzzing coming from? use a wooden dowel as a stethoscope to listen to the componentss. It could also be the relay. If the parts are accessible, they can likely be replaced.

lee h

[Robert Scott]

The relay buzzes more than usual, and sometimes the 6.2 amp fuse blows. I cannot use a higher rating fuse because of the unique base design, nor do I want to. If the fuse is blowing, it is protecting my pump.

Once after replacing a fuse, I found that if I didn't feel the vibrations of the pump in the water line immediately after turning the power back on, then I could tap on the control box and things would start up OK. Sounds like a slugging relay. But it is a special purpose relay made to work in conjunction with the Start capacitor - probably set to engage at a very specific current to switch to the Run mode at the correct time. I would not know where to get such a relay.

Robert Scott Ypsilanti, Michigan

[dpb]

However, given the age of the pump in the original message, I suspect the occasional blown fuse is a prelude to the pump bearings or other problem(s) indicating higher than normal starting torque and the pump (or at least the motor) might as well be replaced as well. Been my experience, anyway, that once the symptoms start showing as you've noted on the starter, you're simply delaying the inevitable and it's certain the pump will quite at _the_ most inopportune time... :(

And, you're right--many of the newer pumps don't have the external run capacitor and that's what's showing up on the resistance measurement. This starter won't work w/ the existing pump. Again, depending on the OEM for Sears at the time, you may be able to find parts for it (the starter, that is), but of that age it wouldn't be surprising if they're no longer available in the exact match.

[lee houston]

Likely a time delay relay- switches after a period of 'on' time. look at the relay- often there's a mfg name or logo and a part number. If the relay contacts are accessible, you might burnish (polish) with very fine grit wet sandpaper. Also when you have the control box open, give it a good visual for loose contacts, burnt spots, etc. Especially check the caps, visually and electrically.

lee h

[Robert Scott]

Well, here is how it turned out. I returned the new control box to Sears (the one with the incompatible specs) and ordered just the starter relay for my old control box. Then when I took the controller apart I discovered the real cause of my problem. One terminal on the starter capacitor had broken off and was making intermitant contact. When it failed to make contact, then the starter winding was not powered. This prevented the pump from starting up which caused the run winding to take too much current, which blew the 6 1/4 amp fuse. I was able to put an alligator clip on the stub of the terminal to make the connection. And for good measure I installed the new starter relay. Now there are no more buzzes, no more sparks, and no more blown fuses. I will be replacing the starter capacitor eventually too because I don't want to rely permanently on an alligator clip.

Robert Scott Ypsilanti, Michigan