Start Capacitor Voltage Rating, 120v stenciled, Motor Wired for 230v Nominal

[UptownSport]

Gents,
Failed Start Cap, I'm assuming it's stenciled 120v, although you can't really tell.
The motor is rated for 120/240v operation, and voltage wiring instruction say nothing about swapping out capacitors.
Is this just for one circuit (120v)? IOW, am I OK with replacing like with like?

Second question, is the corrosion common with Cap failure??

Thanks in advance!

 

[eKretz]

A 120V/240V single phase motor will usually use a 120V cap for the starting circuit (that's in there just to kick the motor to get it started). So yes, you can just replace it with one of those. The question will be what mfd size you need. I guess that's not at all legible on the old one? And they don't always leak like that, but sometimes they do. These types of capacitor contain a liquid or gel electrolyte, so they can corrode steel pretty readily if they leak.

 

[Joe Gwinn]

I bet Leeson can tell one what kind of capacitors to use.

https://www.regalrexnord.com/produc...5-208-230-v-1800-rpm-56c-frame-tefc-112136-00

 

[EPAIII]

A quick search for "start capacitor size for motors" showed many returns for figuring the capacitor size.

start capacitor size for motors - Google Search

There is nothing magic or super precise about the start capacitor. It just provides a phase change to the start windings for the first few seconds after the power is applied. Any capacitor in a wide range of sizes will function. So just pick one from one of the on-line tables or calculators and use it. Chances are it will last for many years.

Like most electric/electronic components, cooling would help extend it's life. The apparent leakage in your photo tells me that heat was likely involved in the failure. The first thing would be to not box the motor in, preventing air flow. Leave some space around it for natural air currents to cool it. A heat sink on the outside of the capacitor's enclosure would also help. And, of course, a fan.

 

[UptownSport]

Thanks, as always Gents!
xxx- 708 uf was legible, and going back and forth on search terms it's 99% certain the first numbers are 590.
Yep, @EPAIII , I always worry why something failed. I have zero idea motors history, it's certainly not original on a 75 yo lathe, so it may have been over heated before it went on the Sheldon.
I doubt it'll ever get warm even being in the cabinet.

Thanks again, hopefully the new cap does it, and it has a long life.

 

[Gordon Heaton]

I don't know why the stinking manufacturers don't put the cap value on the data plate. Some do, and it is nice when it occurs.