power factor correction on laptop power supplies

In Europe if they are rated at > 75W they have to.

Graham

The one I'm looking at right now says 100-240V @ 1.6A input (160W in?), and 65W output (19V @ 3.42A)

(Are they really only 40% efficient?)

Michael

..... Phil

It's higher, just means that the power factor must be quite ghastly. While a good meter may measure 1.6A input current a watt meter won't measure as high as 160W.

Or the 1.6A input rating is conservative, to handle inrush or just on general principles.

Input power I think.

Possibly a fault condition rating ? Odd though. It would get damn hot.

Graham

Just the usual rms to average ratio current of a rectifier and capacitor filter - has a PF of about 0.5

Eg, my PC monitor is rated at 240 volts and 2 amps, but in fact draws only

..... Phil

Gets very warm to the touch when charging the battery. After it's charged, it's quite cool.

Thanks,

Michael

If the device employs power factor correction, the difference between VA and Watts goes to zero, right?

Michael

Try again sometime, pal.

...... Phil

Near as dammit.

Graham

If it employed perfect power factor correction, it would. If it employs practical power factor correction, it gets close enough. In this case, I don't know what the legal definition of "close enough" is.

Yep, nothing in life is perfect... same goes for heat exchangers, electric motors, GAC contactors...

So, if I'm understanding this correctly, I'm paying more money for electricity (and introducing some noise into the grid) if I don't implement PFC?

Michael

snipped-for-privacy@gmail.com wrote: (snip)

You are not paying anything extra for that power factor current if you are an ordinary residential customer in the U.S.A.

You are wasting a little bit of power (that you are not paying for) in the power distribution system, and generating some harmonic distortion in the line waveform.

Ah, so industrial customers pay extra for not implementing PFC?

Thanks,

Michael

Some do see a separate charge for power factor current. But we all pay in the end for inefficiencies of power distribution with a higher price for real power. If most devices included power factor correction, the actual cost of delivering power gets down and the system delivery capacity goes up, Somebody gets that savings.

A PF of 0.5 _is_ ghastly :-)

Yeah, could be. Other times they state the max right after turn-on, when the degausser is busy and other stuff spools up. If yours is a CRT monitor then 56W is pretty decent.