I Need Better Capacitor Understanding

[klind]

I have been having trouble acquiring an exact match for a capacitor that apparently activates a motor in my spa valve control. The schematic details a 35uf 100V 83c non-polar cap. On Line I have found many close to these specs but none are exact. Accordingly, I need to know how much these values can fluctuate. I did find a capacitor with the values 35uf 50V 83c non-polar and I have also noticed that the schematic diagrams indicate that this circuit operates using 24VAC. So can I use a 50V cap? I have also found many that are rated at 33uf and up to 250V. I know that having the capability of 250V being more than 100V would be OK (except maybe for the size), but is it safe to replace a 35uf capacitor with one that is rated 33uf? I also know that most, if not all, capacitors are rated plus or minus so a 35uf will probably be OK if it returns 33uf, but a 33uf might fall below minimum for the circuit. I've studied the net a bit, but I still feel I need just a bit more education. Where do I go to learn more?

[budm]

1) Attach the circuit diagram for us to look at.
2) Attach good clear pictures of the whole top and bottom side of the board.
3) What is the reason for suspecting bad "35uf 100V 83c non-polar cap"?

[klind]

1) See uploaded file.

2) There is no circuit board.

3) Tested bad.

[budm]

AC feeding is only 24VAC? 33uF will be fine since the cap is +/- 20% tolerance.
The sch shows 120V rating for the cap, using higher Voltage will be fine.
BTW, is the old oil-filled type and rated at 120VAC printed on it?
Pictures of the old cap?

[klind]

First, just a reminder that, as previously stated, I am trying to learn.

I kind of don't understand concerning the +-20% thing for two reasons. First, I don't know where that tolerance came from... I didn't list it and I don't see it in the schematic drawing. Second, if the tolerance of a 33uf capacitor is at minus 20%, that would make the capacitor rating below the schematic requirement.

Concerning the voltage, I do understand that a higher voltage capacitor can be used to replace a lower voltage IF it fits the space allotted. However, I still do not understand why I would need a 120V capacitor in a 24V circuit.

I have attached a photo of the existing capacitor.

Thank you very much for your responses. I apologize for being a slow learner.

[budm]

The capacitor you have is 33uF (336, http://kiloohm.info/3-digit-capacitor/336), K = +/-10% tolerance, 100 = 100V. It will be rare to find this type of cap rated <100V.
This looks to be polypropylene film capacitor for AC motor.
What capacitance dopes your cap meter show?

[klind]

I cannot answer you last question as the existing capacitor does not function.

Yes I do believe the capacitor is for the AC motor.

So that leaves me with finding a replacement.

Like I mentioned, I have found similar capacitors rated at 50V, so as this is being placed in a 24V circuit why do I need a 100V capacitor?

Can you recommend a capacitor that would be suitable as a replacement? In the current state of quarantine I need to order on line.

Thanx...

[budm]

"I cannot answer you last question as the existing capacitor does not function." So how do you know if it is bad then if you cannot measure the capacitance?

The kick back Voltage from motor winding can be higher than 24VAC.
Show us exactly what you found on line?
Did you check the motor windings, check the switches? What measurement have you done to conclude that the cap is the problem? Does the motor even try to turn at all?
That motor looks to be gear drive motor with reversible directions.
What does the toggle switch for forward/reverse, that what it looks like to me? What AC V do you have on those Clack, Red, and White wires? Do they go to step down transformer winding?

[budm]

BTW, what info do you have on the motor? It should have some kind of make and model printed on it.
Typical 3-wire AC reversible motor wiring, I redraw your motor wiring as shown in second picture.
I do not have time to search for Axial lead 33uf 100v motor run Polypropylene capacitor.

[R_J]

This looks like a Pentair Compool CVA-L24 Valve Actuator. The cap is nothing special and is nla from the manufacture. Are you sure the cap is bad and not the limit switches?

[budm]

Originally Posted by R_J

This looks like a Pentair Compool CVA-L24 Valve Actuator. The cap is nothing special and is nla from the manufacture. Are you sure the cap is bad and not the limit switches?

+10
I still like to know how he comes up with this answer: "I cannot answer you last question as the existing capacitor does not function.", and still cannot tell us what the capacitance reading is out off circuit.

Hard to help.

[klind]

R_J:

It is a spa valve actuator. However the model number I have is PE24VA. I believe it is identical to the Pentair CVA-L24.

Budm:

I am sure your drawing of the motor is accurate as it is a reversible motor.

Concerning the question in your second drawing the wiring goes to the spa control panel.

Concerning my wording "does not function" what I mean is that I have determined that the capacitor is bad and does not produce a reading on my meter. I apologize for not being more clear. I believe I can cause this valve actuator to work properly simply by replacing the capacitor with a known good capacitor of equal or sufficiently close specifications. So all this is to just find a suitable replacement capacitor.

[budm]

Clarification needed:
So it shows no capacitance at all your capacitor meter? It is pretty rare for that type of cap to show 0 capacitance.
Did you test the capacitor without having it connected to the circuit?

[klind]

My meter would not read this capacitor so I had someone else read it (out of the circuit). I was told it was not within tolerance. Sorry, but I do not know the actual reading.

I still have the capacitor though and if that is important I can have it read again.

[budm]

Your post #5 you ask about the tolerance "I kind of don't understand concerning the +-20% thing for two reasons. First, I don't know where that tolerance came from... I didn't list it and I don't see it in the schematic drawing."
Post #14 : "My meter would not read this capacitor so I had someone else read it (out of the circuit). I was told it was not within tolerance"

So how does the person know if it is out of tolerance when you/ or the person do not know what the tolerance of the cap is? I point out what the value and the tolerance are after you show me the picture of the cap. The person that tests the cap should have been able to tell what the value and the tolerance of the cap are since it is printed right on the body of the cap.

At this point you also need to verify if the toggle switch and the two micro switches are OK or not and if the motor windings are getting the AC Voltage.
Or just buy a new cap and see if it fix the problem.

[R_J]

The 35µf/150 volt (NP) non polarized will work, here is a similar valve

[budm]

So that one they BP Electrolytic cap for running cap in that product? I have never seen lytic cap used in any of my motor repair works.