Let's talk more about PF...

From the formula, we see, if the D=1, ie, no distortion, then PF = cos r. thats we used to read on electric books. As illustrate below.

where Vi and Ii are all pure sine wave.

and here we see, when the r=0; cos r=1, the PF = 1. But when D=\=1, even if cos r =1, the Pf =\=1 ! as illustration below.

This was always met at simple rectifier. Especially when only use capacitors as a filter.

Now, we know what is power factor, next, we discuss how to make power factor correct.

(If we are interesting in , we shall extra discuss the 4 meanings of the PF).

We usually divided PFC into two classes, passive and active PFC.

In electric engineering, we usually take the ways of LC filter or synchro motor. They are suitable for small or high power level situation. As we all know, they have bulky components, but higher reliability and still widely use today, although they have not got too higher PFC.

In the situation of under 2000W equipments, we are gradually adopting active PFC, which is implemented by electronic components. And have more higher PFC than the front has. The component we often use is untrod UC3854 (TI owned now). of cause there are more other components put into use now, like LINEAR's, etc.(but I hvnt ever used them,if you are interested in you can visit their web site)

From the chip diagram block, we see a multiplier/divider inside, which output Vmut equal to A.B/C; where A= k1*Vout; B = Iac =k2*Vin; C = k3*Vin^2;

Then, we get Vmut = (k1*k2*Vout*Vin)/(k3*Vin^2)

And Iin =Vmut/R0; Pin = Vin*Iin = K*Vout, where K = k1*k2/k3/R0, Now we result from the formula that the input power is independent on the Vin, if Vout keep constant. This is reason that why the chip has a M/D part.

Very useful insights on this subject, cnpower. Power factor, and its correction, is one of the more popular subjects on CR4. This insight is given clearly in something other than a native language and native alphabet.

thanks, I wish everone who read it could understand, either words or illustration.

cnpower and others,

Due to a recent Utility rate increase, I am interested in developing power fector correction as a service offering to all my large industrial customers.

Industrial users with large industrial loads pay a maximum demand charge.

If I can correct their power factor, then the max demand will be lowered resulted in a cost saving.

I understand the theory but would like some advise on the type of reliable equipment to use to conduct surveys etc.

My plan is to procure a revenue class meter and clip-on CTs .

Install them on my customer's premises and gather data for two months.

From this I will have a good load profile and enough data to do a cost saving projection for my customer.

I know software exist that can do all this and I would be grateful for any recommendations which you can make.

How much power do you want?

active or passive pfc do yuou want?

how much?

you do it by yourself or buy for your clients?

different answer , different ways. I think.

To be more impression, I illustrate the half wave simulation, from the graphic you can see the distortion has been improved mostly and so that the pf has been rised. of cause.

( the first compare with the third pic)

PFC can be used either at user terminal or at generator plant.

At the side of user, you can get more active power,

at the plant, you can offer more active power to the net.(In fact, at this side, produce more compensation passive power)