On 10/31/06, sPh > wrote:
> > Mike Avery wrote:
> > For some time, I owned a bakery. We had a Hobart 30 quart mixer. We
> > bought it used, and it was probably older than I am. We won't go too
> > far into how old I am, but I am certainly old enough to drink
> > legally... and a good bit more.

> > It had a 275 watt motor in it.

> Question: was that a single-phase motor or a three-phase motor? Many
> commercial units have the advantage of 3-phase power, which allows a
> much more efficient motor design.

You're right, that wasn't comparing apples to apples. It was a
3-phase motor. I just went to the Hobart web page to look at the
current 30 quart mixers... they are a lot nicer than the antique I
had. The motor I had was about a 1 amp motor, and looking at today's
Hobart motor specs, the single phase motor would have been about 700
watts. And I was able to mix about 25 loaves worth of bread with it,
back to back batches, for as much as 5 to 8 hours a day.

The current top of the line KitchenAid, the Professional 600 Series,
has a 575 watt motor, and it can mix up to about a 6.5 pound batrch of
dough, but may not be used for more than two batches in a row. The
difference remains in two factors. One is the motor in the Hobart is
a single phase motor and a transmission that lets it run at its
optimum speed. The other is build quality. However, I don't think
any build quality is going to overcome the inherent weakness of a
variable speed motor being asked to deliver high torque at low speeds.

> It is generally impossible to get
> 3-phase power in a residential structure unless you install your own
> converter (formerly a rotary unit, although I understand solid state
> systems are now available) which wastes a lot of electricity.

I see a lot of talk about 3-phase in the professional bakers mailing
lists I'm on. It seems to run somewhere between 5 and 15 thousand
dollars to run three phase into a building, if the three-phase is
already available in the area, which it usually is not in residential
areas.

On the 30 quart mixer front, a 3/4 hp motor can draw anywhere from
11.6 amps on a 115v single phase circuit down to 1 amp on a 460 volt
three phase circuit. The advantage of the adapter is in saving the
installation costs of the three phase. We got a used motor rotary
unit for about $250. Solid state units are quieter, don't require
lubrication and are more reliable. The other advantage of three phase
is that there are lots and lots of used three phase equipment on the
market for a song. Single phase is much harder to find, and more
expensive.

Mike