Re: Energy - Power Meters
- From: "Michael A. Terrell" <mike.terrell@xxxxxxxxxxxxx>
- Date: Sat, 04 Jul 2009 16:02:51 -0400
Jim Thompson wrote:
On Sat, 4 Jul 2009 18:13:51 +0000 (UTC), David Lesher
<wb8foz@xxxxxxxxx> wrote:
Jim Thompson <To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> writes:
I don't know what "central HVAC" is (so I'd guess that I don't have it).
You don't have air conditioning ?:-)
Jim; not everyone lives in the middle of the desert...
Thankfully ;-)
Remember folks, it's hell-on-wheels out here in Arizona and, with
global warming, it'll get worse... so stay away !-)
WHAT IS your significant consumer.
I'd suspect his fridge.
Probably rents, has steam heat provided. Has no clue that part of his
rent pays for that.
BTW, another poster commented:
The device will not reduce the losses in the motors only the losses in
the conductors between it and the meter. (and maybe not even that)
Not quite true; it will cut the I^2R losses in the motor by reducing the
current.
I realize I forgot part of the spiel re: the NASA story...
So power needed is a function of load. Ask the water pump to raise 6
gallons per minute 8 feet, and it needs mumble_out watts. Make that 12
gallons & 10 feet; it's bigger mumble watts...true?
Each of the output power needs will be reflected in an input power need of
(mumble_out+the losses). And that is I*E*pf, integrated over time.
And:
An induction motor's power factor varies with load. The closer it is to
full load, the better its power factor.
Mumble_out is fixed *by the load* in everyday apps. Changing a variable
must change others so you still get the output.
Say:
Ia * Ea * .8 pf = Ib * Eb * .9 pf
If you improve the PF, and the E is fixed, Ib > Ia.
Ergo, Ia^2R > Ib^2R... lower losses in b.
But the alleged way to lower the pf is to lower the pf and you do that by
loading the motor to full{er} load. But that's fixed, so you lower the E
to improve the PF...but wait, won't that raise I? [Let's not always see
the same hands, class...]
And here's the hype.... when demo'ed at county fairs and flea markets;
the carnie's display ALWAYS showed an unloaded, free-spinning shaft
motor. THAT case could be helped by the Magic box. But in any consumer
fridge, or dishwasher, you know Frigidaire or Kenmore or whoever had
carefully designed the motor to be fully loaded; they are hardly going to
give you more copper and iron than needed, are they? In real uses, as LeRC
tested them, it's no better than a wash.
I vaguely remember some hype about an AC motor controller that varied
its consumption according to load?
Here's one for you... my electric consumption (in kWh) is about 15%
lower so far this year than last... looks like global _cooling_ to me
;-)
Mine have been dropping for several years. Last month was still
under $100.
--
You can't have a sense of humor, if you have no sense!
.
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