Can't find a source for replacement motor run capacitor, size is the problem

Can you confirm something like:

won't fit if you remove the stud?

Otherwise the Ducati 4-16-18 4uF cap seems about right, but that range has fewer suppliers.

Yes, you're right, the 4.16.18 series is the right size as long as cutting the stud off is OK, it looks as if it's just a plastic stud continuation of the case.

Thanks.

Ah, oops, no. The Ducati 4-16-18 capacitor is only 250 volt at 10000 hours. It is rated to 425 volts (1000 hours) but it's getting a bit near the bone. The existing one is 3000 hours at 450 volts.

Something like:

is listed as 28 diameter, and 56 long. I was hoping that length might include the stud, but having just checked the 16uF one I bought recently that was quoted at 70mm long, it does not appear to.

How many hours is this motor going to run?

I agree the 4-16-10 series is more rugged.

The height dimension is the size of the body and doesn't include the stud.

Yes, there's *loads* that size, that won't fit. :-(

Just noticed that Rapidonline do ICAR motor caps - alas only the ali can versions by the looks of it. It might be worth asking them if they could order you what you need.

snipped-for-privacy@isbd.net wrote in news: snipped-for-privacy@esprimo.zbmc.eu:

Why are motors so particular about the value of the capacitor? Why haven't they been rationalised?

I suspect it's down to optimising starting characteristics required for different applications, and reducing costs where possible.

They aren't. A lower value one would work, providing the motor is not operating near the limit of its starting or running torque. However, it would be very bad if one was chosen which didn't generate quite enough torque to start the motor - it could burn out the motor if left energised for some time with a stalled rotor.

I've no idea what the load characteristics of this application is.

What? Motors?

Just cut the stud off

NT

If this cap is fitted in a sheet metal cover fitted to the motor, can you make a slightly bigger cover?

If all else fails perhaps you could fit the next capacity down, and add a physically small cap elsewehre to provide the remaining capacitance.

NT

No, it's in a rectangular case with the capacitor in a tight fitting moulded section. It's not really modifiable, though I guess I could fit the capacitor externally, that would involve running some extra wires.

They don't change size with capacity except in very big steps. To get a physically smaller capacitor you'd probably have to go down to 1uF.

You're pretty stuck then.

NT