Interesting article on PFC

Michael_qrt · Post by **Michael_qrt** » Sun Dec 14, 2003 3:51 am

Here's an interesting article on PFC over at dan's data that I thought I'd bring up for discussion since it seems to contradict what has been said on this site about PFC.

Here's the link: http://www.dansdata.com/gz028.htm

From the sound of it active PFC is still good in many ways but it dosn't save on your power bill.

al bundy · Post by **al bundy** » Sun Dec 14, 2003 4:23 am

Wow, that is an interesting article. Thanks!

Inexplicable · Post by **Inexplicable** » Sun Dec 14, 2003 4:58 am

Hmm, not quite sure how that contradicts anything said here? The claim that PFC reduces efficiency is interesting but hardly surprising, as PFC introduces additional circuitry to the PSU. As ever, efficiency is the figure to look at when buying a PSU. The power factor is fairly uninteresting.

Michael_qrt · Post by **Michael_qrt** » Sun Dec 14, 2003 2:24 pm

Well in the PSU reviews on this site PFC is said to lower the cost on your electricity bill by reducing power lost to harmonics. However Dan says this is actually false and devices with a low power factor are bad because they pollute the mains and cause power losses due to transmission of electricity from the power station due to the real increase in current during parts of the AC cycle.

As you say though, efficiency is the more interesting property of a PSU.

[edit]

In newer PSU reviews on spcr it seems that the power factor is said to maybe reduce your power bill depending on your power company.

In any case from what Dan said with low PF devices the difference between real power and apparent power is not lost as the energy is stored in the device and then returned to the system.

dukla2000 · Post by **dukla2000** » Sun Dec 14, 2003 5:23 pm

I am no expert but my simplified interpretation is this: if you pay for your electricity based on a kW meter, PFC makes no difference to your bill. This applies to all domestic consumers in England. If you pay for your electricity by VA, PFC can save you big money. This applies to many industrial consumers and all 3-phase supplies in England.

However in the big scheme of things the power companies have to cope with the inefficiency (to them) of all the low PFC domestic consumers, and will pass this back to you as a higher price/kW.