Just to let every one know ive thought about it a little more and ive changed my stance and decided he is single phasing that " idler motor " the entire time its operating. Although it would be very hard to prove.
Here's a simple 2hr build converter I use for bench-testing compressors.
The pot. relay/1000mf supplies the lagged 3rd phase.
For a 10hp, 250mfd run evens out the voltage of the 3 phases.
Two junk box contactors & that's it.
Its' windup is instantainous & synced with hydro 60hz.
If you're on a computer, it's in the tool bar. I don't know how to on a phone. Never done it:
Hmm, I'm the guy sitting in the northwoods who has NEVER had the internet (I choose not to).
But now that I see how Quotes are handled, I think that it may be something like [attachment, and put your picture name etc. When there's time will figure it out..
Yep this is just a very simple rotary phase convertor ... The little motor is to just get things spinning. Once the bigger motor is up to speed it is run on single phase. That is why you have to over size it to about 1.5 times of the motor you are wanting to drive. The third phase is generated because the single phase line voltage is magnetizing the iron in the motor and the other phases are pulling the rotor around to cut the flux generating the 3rd phase. The generated leg does have a higher voltage than the other two legs so be sure and never use the generated phase on any controls unless you want to let the smoke out of your coils etc.... As far as any voltage coming out of the little starter motor that is purely an induced voltage that is created by the residual magnetism in the motor. Any 3 phase motor that is rotated will create a back emf that can put OUT as much power as it delivers if the motor is a. connected to the utility and b. turned at a speed that is equal to its normal synchronous speed plus its slip. For example - if you have a 3 phase motor and it is listed at 1725 rpm. The synchronous speed of a 1725 motor is 1800 rpm... therefore there is 75 rpm of slip... if you connect this same motor to the utility and overdrive it to 1875 the motor will be putting out full current to the grid. This is referred to as an induction generator. That is how a lot of wind generators work .