Pool Pump Capacitor

[Zilva]

Is the physical size of a capacitor important? My pool pump is making a habit of blowing it's capacitor ever few weeks. The best price I can see on line for this particular model is $75, however a capacitor with a similar rating, just considerably smaller in size, is around $25.

I'm buying a new pump anyway, however I'd ideally like to get my old one going just once more so I can clean the deep, dark green colour out of the water before running the new pump.

So can someone tell me, as I only need it to work once, would a smaller capacitor of a similar rating do the job?

[Ash]

Heads up boys (and girls) looks like the folks on the other side of the pond are looking to empty the Atlantic and invade the Mother country !

[Rod]

The other side of the Indian Ocean and (maybe) Arafura and Coral Seas as well. (Hint: OP's email address is .au.) Also affects effective meaning of the dollar prices - being not the same as a USD.

[Alang]

There are different types of capacitor. It's quite possible to get identical specced units of different size although a *considerable* difference in size is unlikely. The fact that the installation is blowing capacitors regularly points to a fault that needs investigation.

Try posting the specs of the two caps up here and someone will better advise you

[Bob Minchin]

The capacitor must be AC rated as the same or greater voltage than the old one and of very similar capacity measured in uF or MF (micro farads) They are normally referred to as Motor Run capacitors and something in the range say 5 to 10 uF would cost about 5 UKP here. Some types have tags on the end suitable for push-on connectors or soldering to, others will have a few inches of cable moulded into the body. Most now have an M8 threaded stud on the end for mounting. Of more concern is why the capacitors are failing so quickly. I would expect 10 years plus unless it is running too hot by being in thermal contact with the motor. Maybe consider how/where it is mounted.

HTH

Bob in UK

[Ash]

Aha ... you spotted my deliberate mistake then ?

[Rod]

No - didn't see your deliberate one ... :-)

[Midge]

As per the previous posting, capacitors using the same electrolyte, similar capacitance and similar voltage rating will tend to be a similar can size, so this suggests we're not comparing like with like.

Probably need to be clear on whether this is a start or run capacitor. A start capacitor has different characteristics (and I think a different electroyte) and different range of capacitance. Start capacitors give a short boost to get the motor fired up but don't remain in circuit (whereas a run capacitor does, as its name implies).

If this is a start capacitor, it may be that the mechanism to get it out of circuit once the motor is up to speed isn't working properly (this could be a relay, centrifugal switch, or electronic switch) and voltage is being applied to it for longer than it should be, causing premature failure.

As per previous postings, if you post up the details (rating, manufacturer, part number) it might be possible to find cheaper alternative - $75 seems very steep.

Midge.