Compressor fettling, & capacitor question.

[dobbslc]

I picked this old German v twin compressor up last year and have finally had a go at fixing it. It weighs a ton! And has a massive 3hp motor, it's more motor than compressor in fact!
It sounds slow on start up and sometimes stalls and pops the thermal overload.
The unloader valve was assembled wrong with the needle upside down so it wasn't letting the pressure out of the pipe when it got up to pressure, I've cleaned and fixed that and it's now working well.

Someone has had a mess about with the capacitors and has replaced one with a physically smaller but same spec one.

The motor plate says 40mf on it so do they both need to be 40mf or 20mf each?
Could I replace the start cap with a bigger or smaller one to give it a bit more kick to start it?
If so which way, bigger or smaller?

 

[Seadog]

They're in parallel, so one 40 or 2 x 20.

 

[Bornfree]

That looks an incredibly large motor for 1.2kw.

 

[dobbslc]

It is ******* huge!

 

[Domdom]

40uF is about right for that size of motor, although as noted above, it's big for a 1.2kw. Physically it looks more like a 2kw, or 3hp. Those tend to use 60uF capacitors which you could try. But the thing is, if you go too big the capacitor will never charge up properly to the point where the discharge rate is enough to start the motor. Larger value will discharge for longer but smaller value will give a bigger shunt for a shorter period of time.

 

[500e]

Thought it might be a flame proof due to size and weight but only IP44

 

[grim_d]

At 1.2kw it's a 1.6hp motor, 3hp is 2.2kw.

It's just big boned.

 

[Bornfree]

At 1.2kw it's a 1.6hp motor, 3hp is 2.2kw.

It's just big boned.

They say " inside every fat person there's a skinny person trying to get out" maybe motors are the same

 

[brightspark]

At 1.2kw it's a 1.6hp motor, 3hp is 2.2kw.

It's just big boned.

its an oldie thats why. i have a mint 3hp brooks motor and can hardly lift it its that heavy

 

[grim_d]

its an oldie thats why. i have a mint 3hp brooks motor and can hardly lift it its that heavy

Yeah the 2ish hp in my Elliot mill is a monster as well.

They say " inside every fat person there's a skinny person trying to get out" maybe motors are the same

There once was a skinny person in me...but I ate them.

 

[dobbslc]

At 1.2kw it's a 1.6hp motor, 3hp is 2.2kw.

It's just big boned.

Yeah I realize that now. It just look like a 3hp motor