"Commander Kinsey" wrote in message
newsp.0awg1ojnwdg98l@glass...
On Tue, 22 Oct 2019 10:58:58 +0100, whisky-dave
wrote:

On Monday, 21 October 2019 21:02:48 UTC+1, Commander Kinsey wrote:
On Mon, 14 Oct 2019 13:01:29 +0100, whisky-dave
wrote:

On Friday, 11 October 2019 20:08:35 UTC+1, Commander Kinsey wrote:
On Wed, 09 Oct 2019 14:04:03 +0100, whisky-dave
wrote:

On Wednesday, 9 October 2019 01:08:01 UTC+1, Commander Kinsey
wrote:
On Mon, 07 Oct 2019 12:59:03 +0100, whisky-dave
wrote:

On Friday, 4 October 2019 16:34:01 UTC+1, Commander Kinsey
wrote:
On Fri, 04 Oct 2019 16:28:06 +0100, whisky-dave
wrote:


I just tested one of mine with a meter, and it gave a power
factor of 1.00, at 256V, 9.8W.


I doubt that it's just the LED, you shouldn't include the PSU
in such calculations especailly if running off mains AC,
because you're including the LED+PSU so not really gettign
any info about the actual LED.

Why should I not include the whole unit? Surely that's all
that matters.

That depends on the statement yuo wish to make.
If you want to test the power factor of an LED then that is what
you test for.
If you want to test the power factor of an PSU then that is what
you test for.
otherwise the test is pretty meaningless.

All we care about is the power factor of the whole unit. You
don't have LEDs on their own.

I do in fact most products have LEDs that aren;t directly connected
to mains voltages.
Think or all the LEDS in a TV screen 1000s of them, and in phones.
How about car headlights ?

But what does power factor mean in those circumstances?

Little to the user, but the designer would be interested.

Does it even make sense? Can a DC device even have a power factor?

Yes it can.

What does it mean? I can understand lagging or leading current in AC, but
how can that happen in DC?

The only thing that matters is the power factor presented to the
mains supply,

which could depend on teh rest of the circuit.

on the other side of the LED power circuitry.

whatever that means, do you know.

I mean what the mains sees.

The mains will see what power is taken by whatever yuo are using as a
power supply rather than the actual LED.

Surely the power supply doesn't completely hide its load?

Yes it can.

If you put an inductive load onto the secondary of a simple transformer,
or a resistive
load on the same transformer, can't you detect the difference on the
primary side?

Yes, but that's not the only sort of power supply possible.

A perfect power supply that is completely power factor corrected
and which produced DC which is inverted to say drive an inductive
load like a motor will completely hide its load.