On Sun, 15 Jun 2008 03:07:30 GMT Don Kelly <dhky@[EMAIL PROTECTED]
> wrote:
| Industrial demand metering measures peak KVA demand -not power factor.
This would be a measure of the distribution equipment capacity you need.
The power company may choose to overbuild your feed, and the overall
distribution of the network your feed taps from, and charge you for
having it at the rate applicable to the capacity you need.
| Energy metering inherently measure the kWh used without the need for a
power
| factor "correction".
This is, of course, the electrical energy you use.
| This is no different now, except for the metering equipment, than it was
70
| years ago.
|
| Customer loads do not "have" to be pf corrected. If low power factor at
the
| loads add to the peak demand KVA (and this may not be the case) then it
| would be economic for the customer to add some correction such as
| capacitors or even synchronous motors. If the low pf is at a light load
| time, it may not be worth the effort. It is not a great task to decide
what
| is the optimal correction (which will not be to unity pf) for a given
| situation.
Still, there is some slight energy loss due to low pf. With the low pf
the
current is higher relative to power actually being used, and the voltage
drop
losses are therefore higher. But is the percentage of this loss enough to
worry about? Probably not. Still, modern digital meters can easily (if
so
designed) measure a lot of things, including average watts, average VARs,
peak watts, peak VARs, peaks per phase, peaks of phase sums, etc. Things
with the big costs (capacity maintenance and energy) would be what they
want
to measure.
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