Thanks, LRT, I have had a friend (electrician) look at it because I couldn't see any marks, nor could he. I suspect somewhere around 100mfb. I pulled the top off and being original it's filled with paper, or what was paper, now attacked by water and various insects. I'l attach photos. I'm assuming that I will need a run/start capacitor & not a start capacitor - any clues on that? There are plenty on eBay, but few admit to being both run and start Thanks again John
It's just a start Capacitor as if there were two then the other would be a run cap. I feel you're going to have to speak to someone of a technical nature as to what the uf (microfarad) value should be.
Cheers, BB.
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.
See if this formula gets you fairly close; although, if someone actually knows what was used would be better. I usually leave this up to the engineers that designed the motor.
(I * 1000000) / (6.2832 x Hz x V) = �F (mfd)
The 6.2832 is Pi x 2
I = current draw of motor from Id plate Hz = your local line frequency, I suspect yours is 50 Hz where mine is 60 Hz V = Line voltage applied to motor.
Capacitor voltage needs to be at least a plus 25% of applied voltage for safety and capacitor life. example 220 vac would around 275 vac or higher. Also make sure you use a non-polarized capacitor
From the above formula using 8 amps @ 50 Hz , 220 Vac I get 115.75 �F so I round up to next available size.
You'll find most of the Caps you'd require are in the 450 volt mark, this isn't an issue at all as it has plenty of headroom and will be much cheaper and reliable than a 230 volt unit. Most appliance manufacturers that are using electric motors are using 450 vac caps.
Also you don't have to be super accurate on the uf figure either.
The following unit will be a good reliable component as made for Whirlpool in the USA,
It voltage rating might be more safety as AC does have peak valve of 1.414 x the RMS (assuming 60 hz) value that most of us are usually see it listed as. Here our 240 vac is the RMS value with a peak value of 339.36 volts and the is the peak to value that is twice that. Our line voltage is supposed to be 240 here but it actually measures 260; just a way the electric company got to push a little more electricity thru the line so we use more. So 450 vac rating is within a 25% safety factor reason. They actually back in the 70's were calling it 220 when I was learning electronics.
And from what I understand you're right on the starters. It's the run capacitors that the value needs to fairly close as it controls how much current is used; too little motor won't produce the rated hp and too much just wastes it as excess heat.
Boy I haven't used any 450V caps in a while since vacuum tubes went away like the dinos. Sure help make good foot warmers in the radio shack on cold days. I always like the blue glow of the those horizontal output tubes when things were tuned right. But my longest radio contact was a fellow in Queensland on 1 watt. I had fellow operator running 2KW couldn't even make contact.
Thanks very much for the input. I am guessing from this high tech talk (which is way over my head) that I need a capacitor that is start only (?) and run/start as usually advertised is not that important. Thanks again. I shall follow that link you posted BB
