> Likewise, if one is running, say, 5-10 kVA, it's a lot easier to find
> components to
> handle the 15-20 amps per phase, rather than handling the 50 amps you'd
need
> for single phase. When handling currents over 20-25 amps, everything gets
a
> LOT more expensive: switches, variacs, fuses, fuseholders, plugs and
> sockets, etc. There's a good reason why three phase is popular for loads
> over a few kW, especially if you start pricing good plugs and receptacles
> to handle 10 kVA, (i.e. not stove/dryer plugs which are really designed to
> be plugged or unplugged a few dozen times, at most).
As someone mentioned earlier, re. some Harris power supplies, since the
ripple
coming out of a three-phase rectifier stack is c. 1%, there is a tremendous
savings
in cost and components in the filter capacitor requirement. As found in most
commercial
amps, anywhere from "none" to 4mfd or so is all that is required. A single
oil capacitor
can replace all those stacks of electrolytics. A simpler, smaller,
cooler-running bleeder
resistor across the output is another benefit.
I am afraid we are stuck, at least for my life-time, with single-phase
residential service
here in the USA. It would cost the power providers billion$ to provide a
modern
system that would in turn produce only 75% of their former revenue when
installed.
Fat chance, IMO!
(((73)))
Phil, K5PC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|