Pump capacitor

[sophie999]

Greetings,

I have century 1.5HP pump. Pool is about 6 years old, sparingly used until this year. This year we ran it 4-5 times a week. Summers only.
Indoor pool, so no visible debris, quite clean. Turn the pump and heater for a few hours a day, then shut off.

Pump went bad a few days ago. Humm but no water movement. Company is asking for $600 for parts and labor to replace the pump.

I am trying the new run cap first. 370VAC, 30 microF. A few (silly) questions:

1. Can I use 35microF cap, as it is all I can find now locally. Will this work long term or should I replace it with 30microF ASAP to avoid overheating?
2. The service man said the reason for cap failure is a bad pump. So, even after replacement, it would not last for more than a few months. Is that likely? If it is, I would rather replace the pump now.
3. He also said intermittent use (on/off cycling) is more damaging to the pump that constant use. Is that true? I do not need to run the pump and filter much as it is quite clean and warm indoors. Only use it for a few hours on days I use the pool.
4. Those caps are without polarity, right? Any lead can go to either cap terminal? Also there are 4 individual attachment points on each capacitor terminal. Can I use any of them? Why are there 4 individual "bumps" on each terminal at 90 degree angles.

Thanks very much.
Sincerely,

Sophie

 

[Chasarms]

Are you sure it is a run cap and not a start cap? You will cause stress on the motor if you use the over-sized capacitor as a run cap. I would not recommend it. You can probably get away with that much over if it is a start cap.

The service man is trying to sell you a pump. A capacitor is is an electrical component, and they fail. Sure, it is possible that there are other issues that may have caused it to fail, but it is very reasonable that the cap just failed, and replacing it will allow you to get plenty more life out of the pump. It's a $15-20 experiment. I would certainly try it before I bought a new pump.

It is true that frequent cycling can stress certain parts of electrical motors. You want to guess the most common part(s) that it stresses? Yup, capacitors. They have a limited number of times that they can be charged and discharged before they fail.

You are correct. There is no polarity to those types of capacitors. The reason they have multiple spades on the terminals is to allow multiple wire connections to the same lug if application demands it.

Finally, capacitors are dangerous. They can discharge voltage even after being unplugged. PLEASE be very, very careful, and make sure you are 110% confident you know what you are doing before you start.

 

[sophie999]

Thanks!

I have removed the cap after discharging it. No sparks at all. Unfortunately, my meter does not have the ability to measure the capacitance, but like you said, relatively cheap experiment.
The reason I think it is a run cap is the cap value. I read that start caps have more than 70microF, and anything under 40 is the run cap. Is that true?

 

[Chasarms]

Not all motors have both a run and start cap. If there is just one, I would replace it with a new one of the same value.

 

[sophie999]

Makes sense.
Thanks much.

 

[sophie999]

Thanks everyone for help.
Replaced the run cap. Worked great, at least so far. Will see how long it lasts.

 

[JamesW]

I have removed the cap after discharging it. No sparks at all.

Pump motor capacitors are rarely charged because they discharge through the windings.

If you ever find a charged capacitor, the motor is probably bad.

In any case, it's always safest to discharge the capacitor before handling. Use a 10,000 to 15,000 ohm, 2 watt resistor across the terminals to safely discharge the capacitor.