FILENAMES:

FRW-1.jpg
FRW-2.jpg
FRW-3.jpg
FRW-4.jpg
FRW-5.jpg
FRW-6.jpg
FRW-7.jpg

DESCRIPTION:

These are pictures and schematics for Fitch Williams' single phase 
to 3 phase rotary converter project which was much discussed in
the rec.crafts.metalworking newsgroup.  Posted by Fitch Williams
<frwillia@ptw.com>. 

Fitch provided the following description:

============================================================================

These are pictures of the finished 5hp rotary converter that I have been
posting test data about over the last few months.  I ended up building it in
the balanced configuration to take advantage of the lower idling power
consumption.  

All the pictures are named FRW-n so that they will be grouped together in
the list.

FRW-1 shows the completed converter on its frame so it is portable.  You
can see that the control box has two 4 prong plugs mounted in the side -
this is where the lathe and mill plug in.  having them connect with plugs
makes the converter able to move outside to run the ancient 2hp 3ph 12"
grinder that is arriving anyday now in return for me doing my neighbor an
electrical favor.  The motor is mounted on 4 inner valve springs from an
unspecified V8.  I plan to change these for a better type of isolation
device shortly - but for the record, the valve springs are very very good
as isolators.  There is no perceptable vibration in the frame (1.5" sq
tube) at all.

FRW-2 shows tha back of the frame.  The motor did not have a terminal box
on it so I adapted an outdoor die-cast junction box which was mounted with
rubber isolation to make sure its vibration was damped.  Works just fine.
The wheels came from my Sears Air Compressor which had its wheels upgraded
to pressure washer inflatable tires so it would handle better on the dirt.

FRW-3 shows the internals of the control box.  I used surplus contactors
that have 120V DC coils so there is a step down transformer (upper right)
and a bridge rectifier (on the terminal block in the middle) in the box.
The back side of the 4 pole plugs (for 3 phase) can be seen along the top
of the picture.  The capacitors are mounted using a large screw type hose
clamp to keep them in place.  The starting contactor is on the lower left,
the run contactor is on the upper left, and of course the starting cap is
in the middle between them.

FRW-4 shows the single phase input voltage and current on the top two
traces - voltage is the smooth trace.  On the right of the picture you can
see that the current has an RMS value of 8.45A and the single phase input
voltage is 232.6V rms.  The instantaneous power is shown on the bottom
trace - at the right it shows that the average power being consumed at this
moment was 1.315Kw or 1,315 watts.  The converter was driving the 2hp motor
on the Andes lathe with the spindle at 1,500 rpm when this scope data was
taken.

FRW-5 is a really fun picture of the three phase converter output voltages
measured from line to neutral on the idler motor.  It shows that the
converter really does generate a three phase output.  

FRW-6 and FRW-7 are schematics of the converter.  

Fitch