3 phase question

Hey folks.

I have my rotary phase converter system up and running with a 3hp bandsaw and a 3hp dust extractor wired in.

I am planning to add a Yates-American J-18 planer with a more modern 3 phase motor and would like to fine tune the run caps to equalize the phase voltages as much as possible. Target voltage is 575.

I would like to set some panel meters for displaying voltage.

My question is should I be measuring phase to phase (this is what I have been doing so far) or would it be more accurate (if possible) to measure each phase to neutral?

This is delta configured.

Sorry if my terminology is not accurate.

Thanks, Brad
 
Good evening Brad, I'm cornfused, you say its a "Delta" configuration but then you ask about measuring Phase to Neutral which is a Y configuration???????????????? Of course pure Delta has no Neutral unless its one of those 120/240 volt three phase four wire center tapped Red/High Leg systems.

Regardless, the motor operates phase to phase so that's what you measure.

John T
 
The Delta configuration with a rotary you would measure the voltage between L1 and L2. L3 the voltage is bumped up with capacitors to make up for voltage drop from running on single phase.

What is the target voltage for? I believe the equipment you have is made to run on 220/440V. I don't think you can get 440v on a phase converter.

Right now I run a Newman 24" planer, a Dewalt 16" radial arm saw, a Northfield 12" jointer and a Madison stroke sander off one rotary converter but I don't run all of them at once. I'm not having any power issues. They are set up on 220v.
 
Hey Steven.

I originally built my converter to run a 36" bandsaw I bought at auction.

The motor is built for 575 volts. I am running a buck transformer which raises the voltage to 600 volts and I have a start cap bank on a mechanical contactor to achive the phase shift to start a 5 hp idler motor.

Once the motor is started the voltage is regulated (sort of ) by a run cap bank which is controlled by another contactor.

The output is limited by the current draw on the 240 volt feed to the buck transformer.

Brad
 
Hey John.

It is indeed a delta configuration. I was just wondering if there was a different method to more accurately measure the voltage on the induced 'leg'.

I have a safe, working configuration now but would like to fine tune it as much as possible.

Right now I have to shut down the entire system to change the value of the run caps (arc flash concerns) and then test each leg but it would be much better to moniter and adjust dynamically.

Thanks for your reply, Brad
 
David G

You still need capacitors to balance a rotary phase converter.

I've built two of them.

RT
 

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