On 2013-09-16, Karl Townsend wrote:
I'm building a phase converter for my son... My third one.

We're using two motors. A 5hp start unit and a 20 hp run unit for a
total of 25 hp. Using a 3 phase load center panel to distribute all
the wiring. Each of these motors will have a circuit breaker going to
a motor starter contactor and then the motor. As an aside, the load
center will make it easy for him to add machines as needed.

I'm doing the control work for him after he gets the power wiring and
panels for the above installed. So, I read up on the needed start cap
size he
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
Looks like 200 MFD will bring it right up. Note: all these plans show
a potential start relay to hold in these caps for a few seconds and
then drop out - spendy little device.

Now I want to balance voltages in the running unit using run
capacitors. An expert named Fitch gave me the attached report on
balancing. it shows I'll need around 300 to 400 MFD run caps between
each single phase leg and the "wild" leg


Then a huge simplification occurred to me. Why even use start caps?
Put the 300 or so run caps between L1 and wild in with the first five
hose motor. it will start right up.

OK, wait five seconds and start motor two, the large one. Put the rest
of the caps behind the motor start contactor on this unit.

No start caps, no potential relay. Anybody see why this won't work?

I did the same thing. It worked well. Of course, I no longer need the
phase converter, since I moved my business to my warehouse.

i

Special note, I also asked on a place that will host Fitch's .pdf. Get
it he
http://www.weaponsguild.com/forum/in...;topicseen#new



Karl