[TowerTalk] Power Distribution

[Jim Brown]

On Sun, 8 Aug 2010 10:17:39 +0200, Milan DlabaŠ wrote:

>most of family houses in Europe (even in Czech
>rep.) - probably more than 90% of family houses have 3 - phase  power 
system
>as normal way.Peak input power of my house is around 20 kW - including heat
>pump, washer, dryier, el.stove, ham radio  and etc. and still we have input
>circuit breaker 3x32A.I thing, that this is normal modern way how to do 
it.I
>can not imagine 200A input circuit breaker .

Question. How much equipment actually RUNS on 3-phase power? Does your 
refigerator connect to a 3-phase outlet?  Your washer, dryer, heat pump? 
Stove? Or do they connect to ONE PHASE of the 3-phase system that comes into 
your home? Same question for the guy from Anaheim. :)  

I'm asking this because I've never SEEN a 3-phase home appliance. Maybe they 
exist, and I live a sheltered existence. :) Remember, I said that except for 
running big motors, there was no good reason for 3-phase. Several suggested 
big DC power supplies are easier to filter, and that's certainly true, and I 
would do it for a broadcast transmitter, but not for ham power levels (at 
least not legal ones). Remember that what you might save in filter caps you 
might pay back with buying three smaller power transformers rather than one 
larger one. :)  And, for that matter, there are switching power supplies, 
and they don't have to be noisy if they're done right. 

As to big air conditioners -- I can't even dream of owning or using one. I 
live in California, where my monthly bill for power averages $180, WITHOUT 
air conditioning, thanks to a billing rate of $0.42/kWh if our monthly draw 
exceeds a rather low limit. That rate increases again if I add air 
conditioning. My major cost is pumping water from the well. And yes, three-
phase motors would be more efficient -- IF they were available in sizes that 
matched the uses of a single family home. :)   

>Your system is older and I
>understand, that rebuilding could be quite expansive.

Yes, the infrastructure cost is the killer. As Jim Lux noted, it's far 
easier to do it right when you're forced by history to start from scratch, 
as was the case in much of EU after WWII (and in other countries much later 
in time). Heck, when I was a child, I learned that there was still a lot of 
DC wiring around NYC!  

73, Jim K9YC