Domestic water pump sometimes "sticks" on starting - new capacitor needed or what?

There's a pump which boosts pressure to the cold circuit (taps, bog etc) in our house when a tap is turned on.

About 1 time in 5, it won't spin, but just sit there humming. As I suspected, the electric meter spins pretty quickly when it's stuck like this!

The main plate on top says: OSIP Electropompe Tpe VCB45/42

0.33Kw 220-240v 2.5a 8=B5F Vc:450 Hz:50 IS.CL:F

Inside, there's a capacitor. It says: Italfarad - 05/90 (date of manufacture, I'd guess) RP-3 10040 =B5F: 10 =B15%b

450V~ DB HPFPU 400V~ DB HPFNT

------------------------------

500V =B1
Reply to
lardconcepts
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There's a pump which boosts pressure to the cold circuit (taps, bog etc) in our house when a tap is turned on.

About 1 time in 5, it won't spin, but just sit there humming. As I suspected, the electric meter spins pretty quickly when it's stuck like this!

The main plate on top says: OSIP Electropompe Tpe VCB45/42

0.33Kw 220-240v 2.5a 8=B5F Vc:450 Hz:50 IS.CL:F

Inside, there's a capacitor. It says: Italfarad - 05/90 (date of manufacture, I'd guess) RP-3 10040 =B5F: 10 =B15%b

450V~ DB HPFPU 400V~ DB HPFNT

------------------------------

500V 120/10 400V H250 25/85 360V

So, there it all is! Do capacitors fade over time? Anyway of testing with yer standard =A35 Maplin yellow multimeter? Any ideas greatly appreciated. Thanks!

Reply to
lardconcepts

Yes, although it's sometimes obvious due to the guts spewing out. The capacitor failing will result in reduced (and eventually no) starting torque.

Yes (actually, don't even need a meter). Impedance of an 8µF capacitor is about 400 ohms (at 50Hz). That's also about the resistance of a 150W mains light bulb. Temporarily remove the capacitor from the motor. Find a 60W or 100W light bulb (filament), and wire it up to the mains in series with the capacitor. (If the capacitor has a metal case, for safety's sake, assume it could be live during the test.) The bulb should light up at significantly reduced brightness, and if left on for a while, the capacitor should not get hot. The capacitor is dead if the light doesn't light at all, lights at full brightness, or the capacitor gets very hot.

Reply to
Andrew Gabriel

A non exact test is to use an ohms range - when you probe the cap out of circuit (make sure its discharged first) you should see a reading that starts low and then rapidly rises, swap the leads round and it should repeat. Much more satisfying on an analogue meter it has to be said. It won't give you a reading of the actual capacitance some posh analogue meters can do that for small caps, or a LCR meter is needed for larger ones), but it will give you an indication that it is at least functioning - and you can compare the behaviour against a known good one.

Reply to
John Rumm

They generally fail rather than fade. It is a motor run capacitor on that motor, not a motor start, so it is in circuit all the time and if faulty you would also get a lot of motor vibration when running as well as starting problems.

If the fault is intermittent starting I'd look first at the pump and bearings - is it binding at all? Induction motors have relatively poor starting torque and a small obstruction can prevent them starting reliably.

Reply to
Peter Parry

Well, thanks all - capacitor checked out fine, and I learnt why a capacitor is used to run an induction motor - to create an offset voltage so it knows which direction to twiddle! I'd forgotten all about that...

Anyway, turns out to be stickyness - the cooling fan on the end was running, so I pulled the fan back to where it looked like it used to rest on the shaft, then it started leaking water. An hour later, I'd taken the whole damn lot out, plumbed it straight through, and without all the gubbins in the way, the water flow is better anyway! (Still not quite pumped level, but perfectly acceptable).

The whole thing was a complete bodge anyway - no idea who did it, but it's gone now!

Thanks for all the help and advice.

Reply to
lardconcepts

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