Re: 3 Wire Motor -- Help

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "marlow by way of Terry Fritz <twftesla-at-qwest-dot-net>" <marlow-at-rconnect-dot-com>

I would make a trip down to your friendjy neiborhood electric motor repair
shop and they should be able to show you whats up.

Marlow
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, October 16, 2002 9:28 AM
Subject: 3 Wire Motor -- Help


> Original poster: "Jeremy Scott by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<supertux1-at-yahoo-dot-com>
>
> Hi,
>
> I've got a 3 wire AC motor here, 1800/1500RPM, 10 MHP
> 1 phase 50/60hz
>
> I'm trying to figure out how it works.
>
> First off, I've ripped it apart and it does not
> appear to have any 'flat' spots on the rotor, nor
> are there any 'dead' spots in the stator.
>
> There are four wires, one of which is a definite
> ground since it's screwed into the casing. The other
> three are red, blue and yellow.
>
> The resistance between the red and blue is 286 ohms,
> the resistance between the red and yellow is 212 ohms,
> and the resistance between the yellow and blue is 74
> ohms. The motor's engraved data says it's 1800 RPM,
> 115VAC, .45A
>
> When I apply voltage across the blue and yellow leads
> (74 ohms) the motor won't spin and draws about .7A.
> When I give it a little push, it spins up to full
> speed and pulls .6A -- so I think I've found the right
> power leads. (I = R/V = 74ohms / 120V = .6A - close
> enough?)
>
> The question is... 1) how do i get it to start without
> a push, and 2) I know it has something to do with a
> capacitor and the red lead :)
>
> Should i just wire a high ufd AC cap end to the red
> lead, and the other cap end to one of the power leads,
> or do i need some sort of switch/capacitor to start
> it, then take it out of the circuit once it's up and
> running?
>
> thanks in advance
>
> -jeremy
>
>
>
>