Capacitor question

[intrepidity]

Trying to replace a capacitor with specs: 20+10uF 300v

But can only find (Amazon) one with 370v, all other specs matching.

This is a dual start capacitor for two 300v motors. Will it burn the motors? Is there a simple modification to reduce the voltage? I'm just learning this stuff, so excuse my ignorance..

ETA: I just asked chatgpt and it said it is fine. Is AI trying to kill me?

ETA2: Uhoh, after grilling it for awhile, now it says this:

Yes, it is both "generally safe" and "potentially dangerous" at the same time. Replacing a 300VAC capacitor with a 370VAC one can be done safely as long as all other specs are the same, but it is important to make sure that the new capacitor is rated for the same voltage as the original one, to avoid any potential damage or fire hazard.

[mahatmakanejeeves]

1. The ability of the capacitor to charge up to a higher voltage than called for

should not be a problem. It's the underrated ones that will fail in service.

Did you try Grainger?

Where did you find a 300-volt motor?

[IbogaProject]

2. this?

https://www.mouser.com/ProductDetail/Hartland-Controls-Littelfuse/CAP-20-10-440R?qs=TuK3vfAjtkUyLxwJ9ZQ9%252Bg%3D%3D

[Shermann]

3. The capacitor will only discharge up to the voltage level that is applied to it

If all other specs are the same, it should be suitable as a drop-in replacement.

I'm not familiar a "dual start" capacitors but believe it is effectively two capacitors.

[intrepidity]

5. Sorry for the delay...but what do you mean by

"voltage level that is applied to it"?

And yes, a dual means it has two hot leads with different ratings, in my case, one each for 10uF and 20uF, to start two motors (like a compressor and a fan).

[Shermann]

7. If you apply "X" volts to a capacitor when it is charging

...it will then only output up to "X" when discharging.

The voltage rating only specifies how big "X" can be. So, you can use a capacitor with a higher voltage rating as a drop-in replacement without risk of it discharging a higher voltage.

It's really better to play with breadboards with 5V or so than 300-volt motors. This is kind of an unusual thread that way.

[intrepidity]

8. But this is AC

So 120v

[Shermann]

9. Basic concept applies regardless of AC or DC nt

[usonian]

4. Should be fine.

Take note that a capacitor's voltage rating is not the voltage that the capacitor will charge up to, but only the maximum amount of voltage that a capacitor should be exposed to and can store safely.

http://learningaboutelectronics.com/Articles/What-does-the-voltage-rating-on-a-capacitor-mean

[intrepidity]

6. Thanks for that link

Although in that page, it seems to only discuss DC power. Mine is AC, so I'll have to see how that might alter things.