DIYbanter - View Single Post - Unbalanced Phase Converters and Power Loss

wrote:

I use a 7.5HP rotary phase converter to run my 2HP Sheldon Lathe. I was
taking a medium cut in some 1020 steel in backgear and after a couple
of passes it seemed that the lathe was losing power. I opened the
cabinet up and the motor was very hot. If I disengaged the power feed
and retracted the tool the lathe would come back up to speed.

The motor is the original and it is wired properly at 220v.

Is it possible that the converter not being balanced or tuned is
causing this power loss. Bob Swinney sent me an article on balancing so
it will not be a problem to do so as I have ordered some run
capacitors.

I do not have the voltages right now on the 3 legs. Should I measure
these with the lathe running with no load?

Thanks, Steve

Install three 220 volt low wattage light bulbs across the phases. It is
the simplest way to monitor the voltages. You can easily tell a 10
percent difference in voltages at a distance. Remember that your phase
shift from the converter is only 120 degrees at one power loading unless
you can vary the reactance between the phases.

John