3-phase (was: Re: CDC 9766 Drive and packs)

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Thu Feb 4 03:18:10 1999

>>My parents have 3-phase electricity at home, but I don't (yet). But I
>>think it's more common in the UK than in the US. (BTW my parents have a
>>16th century farmhouse which they heat electrically during the winter.
>>Maximum load we've measured, 36kW.)
>
> 36kW!! Ouch! And cost of electricity is, I understand, higher than in the
> US, true? Except Jamestown, we pay only $0.03565 per KWH :-) so
electric
> heat is not such a financial killer for homeowners (or for nuts like me
> with working big iron computers in the basement).

Dual tarriff (?sp) is quite common. The most usual scheme is called
"economy 7" which charges about 14c US per kWh during the day and somewhat
less (I think it's less than 5c - sorry, I am not in the UK this week so I
can't check) for a seven-hour period starting at midnight +/- one hour
(exactly midnight on older installations). Some circuits - mainly heating
- are controlled by the same timeswitch (older installations) or radio
receiver (newer ones) as the tarriff selector on the meter.

It is said that many night clubs use economy 7 tarriff despite no heating
load...

Other schemes exist. One called "heatwise" also gives you a couple of
short periods of cheap power during the day...


> Yes, very few private residences in North America have 3 ph power
_unless_
> it was asked for and installed, of course at an extra co$t. If someone
has
> a garage or machine shop at home (and the local zoning laws permit it)
then
> 3 ph can be installed. Otherwise, bigger apartment buildings, larger
> offices and factory buildings are usually wired for 3 ph at 240 volts or
> 480 volts.

Gosh. I've seen 3-phase 208 volts in the US, but what would they use 240
for?


Philip.
Received on Thu Feb 04 1999 - 03:18:10 GMT