I friggin give up....
WHY, WHY, WHY do you need a pony motor for a 20 horsepower idler????
A few thousand Mfd worth of starter caps, and it will SNAP to full RPM
in a Fraction of a second..
WHY make it so extra complicated?
Dont give up so quickly. You can learn about this stuff if you take just
a little time to think about it.
Some people just like the use of pony motors. They dont consider them so
Some people have difficulty getting their capacitor switches to live due
to contact arcing.
Some guys even blow up capacitors due to inappropriate On time.
Sometimes capacitors are not reliable.
Spinning up rotary converters is kind of a presonal preferance thing. I
use capacitors and a solid state switch for my 3 phase motor spin up.
Yes. Mine was slightly more clever than this.
1) I used two contactors instead of 3. Which worked well, they just
needed to be wired differently.
2) The first motor had a capacitor on legs 1-3. It assisted with
starting, but resulted in unbalanced 3 phase.
3) The second motor had a capacitor between legs 2-3. When it was
connected to the network, the capacitors became equal between legs 1-3
and 2-3. That resulted in a much more balanced 3 phase.
On Tue, 19 Feb 2008 17:27:55 -0800 (PST), rpseguin
It's NOT true. I originally had my 20hp converter hooked up to a 60amp
breaker. Never had a problem.
I changed to a 100amp breaker when I hooked up the second converter.
Both converters, the 20hp *and* a 15hp, running off the same 100amp
breaker. Both converters ran daily, for 4 years. Never even saw the
On Wed, 20 Feb 2008 16:02:46 -0800 (PST), rpseguin
You can always contact Reed @ Convert-A-Phase.
He's here in Escondido. I bought a 20hp box from him. Start caps, run
caps, all set up and ready to go. Bought a used 100apm disconnect from
him, and hooked up my own 20hp motor. Even got him to come over to the
house and tune it for me.
IIRC, the control box was just under $500, and maybe another $100 for
the disconnect. But that was 11 years ago.
It might be cheaper to build it from scratch, but the peace of mind in
knowing that you have all the right caps, and everything is connected
properly, and all you have to do is run your 220v to the box, is worth
every penny you'll spend on that control box, IMO.
Also bought the 15hp box from Reed and added my own disconnect and
motor. I mounted both of them on wooden frames and hooked them up to
breaker boxes, and had breakers for each machine. The 20hp ran 4 cam
operated Swiss screw machines, a CNC Gang Tool lathe, a tool grinder,
a bridgeport, and an engine lathe. The 15hp only ran a Tornos 5-axis
CNC Swiss. You'll notice voltages increasing and decreasing as
machines are turned on & off. I didn't want to take any chances with
Warning! DON'T mount them on wooden frames! At least don't mount the
motor on wood. I made the base out of 4x4's, with a double thickness
of 3/4 plywood and bolted the motor to it. Big mistake! Those things
make a constant humm anyway, but the wood was the prefect acoustic
base it needed, and it amplified the hummmmmmm. Drove me nuts!
That made me laugh. I mounted one of our home made cap-style 10hp
rotary converters on rubber and it made it's hummmmm about 10 times
louder too. It is back on the concrete and barely audible again.
On Thu, 21 Feb 2008 09:07:06 -0800 (PST), "Dave, I can't do that"
Really!? How about that. I would have thought the rubber would help.
I may wind up back in the garage. Still have the converters and was
planning on making a heavy steel frame, with rubber feet, or put it on
A friend has a 10hp that is mounted on two pieces of steel channel.
The control box is attached to the rail/motor, and it just sits on the
floor. The disconnect and breaker panel are mounted to the wall. It's
I kind of liked having it all together in one unit. Makes it easy to
move around when needed. Perhaps I should reconsider.
But then, I've also thought.......
If I have to do it again (move back to the garage), the converters may
wind up out in the shed:-)
The hummmm noise is mostly due to field imbalances in the
converter. In other words, they are an electric problem. My old
converter was making a lot of hummm, but on my new one, all noise is
from bearings, fans etc and is all high frequency. No hummm. That's
because it is electrically balanced.
The Cedarburg converters are like this, they are essentially
just a starting capacitor and a relay to switch it in when
needed. They are horrible pieces of junk, barely adequate for a
water pump, I'd hate to see you use one on a CNC machine.
Also, some motors run well on these (Bridgeport J-head motors,
for instance) and some run hot, have little torque or otherwise
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