On 6 Oct, 16:23, (Andrew Gabriel) wrote:
In article .com,
writes:



On 6 Oct, 09:23, (Andrew Gabriel) wrote:
In article . com,
writes:

On 5 Oct, 23:51, Rumble wrote:
wrote:

snip

When you measure the power factor, are you measuring it for the device
in question, or are you measuring the average for the neighbourhood?
A plug-in device can only measure it for the load running through it.

Are you suggesting it somehow compensates for the power factor of the
supply automatically?

Is this a trick question? The supply doesn't have a power factor; only
the load has a power factor.

It wasn't supposed to be a trick question. The supply has a power
factor by definition.

In which case you'll have to give your definition, because it
is meaningless with the standard definition of power factor.

Well, it's not _my_ definition it's _the_ definition. Perhaps you
could Google for one?

I am very familiar with the standard definition which applies
to loads, having designed and built a true power meter myself
some 25 years ago, and having explained power factor many times
here over the years.

You'll have to point out a definition of power factor of a
supply, as that's not covered by the standard definition.
Google draws a blank too. The only related thing I could think
of would be a measure of the worse power factor load a particular
supply can drive, but even that's meaningless as supplies
are rated in [k]VA and in many cases can handle worst case
loads with a PF of zero.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

I'm clearly trying to discover whether the power factor I measure is
affected in any way by the electricity network. If you put a purely
resistive load across the supply coming into your house, are you
guaranteed to measure no phase difference between the voltage and the
current? If the phase difference is zero, then the power factor of
your supply is 1.

There's a whole load of stuff on the web about the lengths the
National Grid go to power factor correct their supply. Perhaps you
should ring them to tell them they are wasting their time?

T