Submersible pump problem

[Antony2008]

I have a SIP submersible pump, SUB 2012-FS that has ceased to pump.

The water level had risen with the float switch closing, but the pump just buzzed and didn't pump. I removed the pump, checked the impeller was free to move and there was no debris present. I put the pump back and it ran but wasn't pumping water... . I turned off the power, then back on again but the pump just buzzed.
I removed the pump and, using a multi-meter, measured at the the plug that the winding resistance (22Ω) was constant through a full rotation of the impeller. I disassembled the pump and disconnected the 8uF capacitor and checked with a multi-meter that it charged and discharged OK ; I also connected it in series with a light bulb to see if it failed under load but it worked OK (glowed dimmer).
I replaced the capacitor, re-assembled the pump and plugged in on the bench. On activating the float switch, the impeller jumped slightly but the motor didn't run. A slight tap with a screwdriver started the pump running. Oddly, the impeller jumped both clockwise and anti-clockwise.... . I'd guess that when the pump ran in the water but didn't pump, it was running the wrong direction.

Can anyone who knows more about motors please explain what is happening and what, if anything can be replaced/done to repair, rather than replace the pump.

Antony.

PS - not sure whether another forum would be a better place for this thread ('tho 'electrical' seems to deals with house electrics).

 

[SFK]

A slight tap with a screwdriver started the pump running.

The fact that it does start with a mechanical nudge sounds like a motor starter capaciator issue to me.
I would replace the capacitor with a new one.

(I read your text as you replacing the original capaciator back into the motor after testing it, and did not replace the capaciator with a new one - but happy to be informed if I am wrong on that).

SFK

 

[just pumps]

Sounds like motor windings breaking down when under load if you replaced the capacitor.

 

[Antony2008]

Many thanks for your replies 'SFK' & 'just pumps'.

Given I don't have a replacement, I did replace the original capacitor as I thought the load test with the light bulb staying on suggested it was OK (or am I barking up the wrong tree ... ?).

One thing I didn't mention was that there had been a very slight amount of water inside the electrical wiring area of the motor ; the wires exiting the casing were also damp... . The rubber seal (that seals the electrical area) was unmarked. I subsequently sat the motor on the radiator over night, then applied HA6 marine grade RTV silicon sealant to the inner entry points of the power cord & float switch.
Given this additional info', is it likely that the motor windings have been adversely affected?

I can certainly order another capacitor if the consensus is that it would be worthwhile.

Many thanks again.

PS - Could I ask, what is/could be causing the pump to run in both directions?

 

[HERTS P&D]

Just buy a new pump Ant.

Andy

 

[SFK]

Agree - at that price for an important application I would buy a new one and have this one as a spare.
Especially as a brand name capacitor will be £12inc shipping.

The capacitor might work on a bulb, but its value will be tuned to what is needed for the motor.
So being old it might light a bulb but not discharge correctly to start your motor.

 

[just pumps]

Still say motor windings, getting wet hasn't helped.

 

[Antony2008]

Thanks again for all your input guys.

As for the application, the water level of a sump in the cellar rose to floor level only once (after seriously heavy rain) in several years, which prompted me to buy the pump in the first place. As there isn't a constant necessity to protect (cue the next biblical 40 day downpour...), I'll initially get another capacitor to see if the original pump will run - (seems a waste not to try...). If it doesn't, I've already sourced a provider for a replacement.

Antony.

PS - In trying to satisfy my own curiosity, I came across this website which some might find useful/interesting - Electric Motor Rotation Direction, Which way does an electric motor spin? Do some electric motors reverse direction? (inspectapedia.com)