On Sat, 19 Apr 2014 07:12:25 +0100, John Rumm wrote:

On 19/04/2014 01:09, Uncle Peter wrote:
On Sat, 19 Apr 2014 00:43:30 +0100, John Rumm
wrote:

On 18/04/2014 11:01, Uncle Peter wrote:
On Fri, 18 Apr 2014 10:44:39 +0100, Andrew Gabriel
wrote:




Yes. They generate 3rd-harmonic distortion, which can be bad in large
quantities because it adds together in the neutral line, rather than
canceling out between phases.

And I guess there's no way to cancel a harmonic like you can shift
normal PF with a capacitor.

Its not easy once the harmonic content has been created. The PFC built
into modern SMPSUs will suppress the creation of it by spreading the
duration of the current draw by the PSU - rather than just concentrating
it at the peak of the voltage waveform.

These are modern SMPSUs, just very cheap ones (about half the price).

Anything over 75W is required to have PFC these days...

They have passive PFC. But that's ****. It's still got a PF of 0.67 measured by a few meters. Verified by 2kW of it heats up the wires as much as 3kW of heater.

--
The modest young lass had just purchased some lingerie and asked if she might have the sentence "If you can read this, you're too damned close" embroidered on her panties and bra.
"Yes madam," said the clerk. "I'm quite certain that could be done. Would you prefer block or script letters ?"
"Braille," she replied.