Capacitor Question

[outlaw....1]

I have a Kubota AE4500 that had  one of the two capacitors go down..
The caps are hooked in parallel.
The markings on the case are sh-mpp 300 vac 10uf u-conn j . Kubota part # 18600-0283-0
I have yet to find one. my questions is could I use a  20uf start or run cap in place of the oem .Witch one to use or what do you recommend  .

Thanks Ken

[deeiche]

rm /

[mobile_bob]

always use "run" type capacitors, the start types are not made for anything but very intermittent service.

bob g

[deeiche]

rm /

[mobile_bob]

i am not positive, but i would bet a dollar to a dog turd that the OP genset uses the two capacitors
in the excitation of the generator, and as such are in continuous duty use.

start caps are not meant to be used under continuous duty and will soon overheat and fail
run caps on the other hand are meant for the run winding of a motor where they see continuous use.

so for a generator i would choose the run caps over the start caps, because i think the start caps will just overheat
and fail, sometimes spectacularly.

run caps are generally more expensive, but i don't think this is the place to save a few bucks.

iirc surplus center has a wide assortment of either type of cap, and the prices are quite good.

bob  g

[rcavictim]

A motor run cap may be used to replace a motor start cap in any application.  The reverse is not true.  Motor start caps are designed to be used intermittently and they consist internally of two inexpensive electrolytic caps inside wired back to back.  On the other hand a motor run cap is usually a foil, plastic dielectric of very high quality like polypropelene and oil.  I have gone to using motor run caps in my very high end DIY vacuum tube amplifiers and loudspeaker crossovers because of their super quality.

Motor start caps and electrolytic caps in general use a thin coating of insulating aluminum oxide inside as the dielectric.  This actually forms in an electrolytic process when the cap is first formed at point of manufacture by applying a increasing voltage to the terminals over time. The caps contain a moist chemical paste to facilitate this process.  If motor start caps and electrolytic caps in general sit for many years, even brand new, this dielectric coating breaks down and placing such a new cap into full voltage service can have spectacular results. The coating can often be 're-formed' by slowly applying a rising voltage over time. Motor run caps on the other hand do not have this formed dielectric inside and you can clobber them with full nameplate voltage even after 50 years in storage without any problems.

[outlaw....1]

I did some more digging and found these.http://mefastparts.com/cbb6120uf450vaccapacitor.aspx

that should get it up and running..
Thanks
Ken

[rcavictim]

I did some more digging and found these.http://mefastparts.com/cbb6120uf450vaccapacitor.aspx

that should get it up and running..
Thanks
Ken

That doesn't look right to me.  It seems way too small for a capacitor with those ratings.  2uF @ 450 VAC is more like it.

Here is the real deal for $3.99
http://www.surpluscenter.com/cart.asp?catname=electric

if that link dono for work try this page.
http://www.surpluscenter.com/sort.asp?keyword=EMRC&catname=electric&PAGELEN=20&PageNo=3