Ok after lots of searching and reading on here... i think i have a pretty good idea of things, but i want to verify / clarify....
For a start cap on a RPC... you need a single cap, of AT LEAST the line voltage (but more doesnt hurt) and at 60 to 70 uf per HP.... some say 100uf/per hp...
so questions remaining are...
1. Is there a limiting factor on the voltage thing? like if you had a 200v cap, and you needed a 110v cap... do you lose or sacrifice anything going with the larger one?
2. the other side of it... I have a cap rated for 200v, 250v max... would this be dangerous to use on a 220/240v system?
3. to figure out #2 you need to know the voltage your dealing with... in a household "220v" system using 2 hot "110v" lines from the breaker box... is it really 220v? or is it 240v?
4. Why isnt it called 110v 2 phase? as that seems to be what it really is now learning about 3phase... and why is 3phase considered 220v 3 ph... seems to me that it should be 110v 3ph... or 330 3ph... if 2 legs of 110 =220v then 3 legs of 110v should = 330v? no?
5. My original question was can you have too many uf's? like is there an advantage of 70 over 60 per hp? is there anything wrong with 100uf/hp?
I gather that higher uf ratings can start a motor faster... but draw more power... but i heave also heard it said that too large a cap can actually hurt starting, and make things take longer to start up and still use tons of power.
I have a whole bank of 5400uf caps that i pulled out of an old machine that i updated. I need a start cap for my RPC, and was hoping i could use some of these... But i assume these are WAY WAY overkill for a 7.5hp idler. I just hate to go out and buy components when i have a box of them already sitting in front of me.
6. assuming i cant use them for my RPC, any idea what would actually need 5400uf caps?? and like 6 of them!!! im just amazed at what could possibly use that. they are rated for 200v, 250v max.
If i cant use them for my RPC, i would really love to figure out another use for them... just seems too cool to have a box full of them and not do something cool with them.