Q factor

Is the quality factor determined from the components characteristics of the LC branch from the de-tuned capacitor system or its a value imposed imposed while doing the conception?

Thanks

Resonnance?

Hello,

I am having problems understanding the principals of operation of a de-tuned filter for power factor correction in an industrial network polluted with harmonics? The fifth and the seventh are pretty high on the network I've checked out. Now a reactor of 7% was used and tuned to the 3.78 (228Hz) harmonic, below the fifth to reduce the effect of resonnance. Global compensation will be 300KVAR with 60KVAR steps. Now what I have done is found the equivalent impedance for one phase of the network in parallel with a 60KVAR bank and plotted it. Impedance will attain a maximum value when capacitive and inductive reactance are equal. Now when that happens, I can solve for frequency and find out that the resonnant frequency (when capacitive reactance from power factor unit is equal to inductive reactance of the load) is 440Hz, which matches the peak value of the curve plotted for impedance versus frequency. This is for one 60KVAR step. This is fine since the de-tuned frequency is 228Hz. When all 300KVAR are are on the load has changed and so has the impedance. Plotting the same data will result in a peak impedance occuring at roughly 200Hz? How can I make sense out of all this? When the load changes, so will the resonnant frequency of the network. A de-tuned reactor is suppose to be set at a frequency that is safely below the expected resonnance points so that it is still safe even with large load changes. Maybe my calculations are wrong? I don't know...

Thanks for your help!

Power factor line Reactor calculation?

Hi,

We will be installing a de-tuned power factor correction system and I had a few questions regarding the calculation of the line reactor. Our distribution system is 600V, 60Hz and each step for the power factor correction is 60KVAR for a total of 180KVAR on one distribution pannel and 120KVAR on the other one (two 1500KVA TX in parallel, Z=5.83%). Before the reactor is installed, we're able to determine that the value in Farad for the capacitor is : C = KVAR / 2*pi*f* V^2 = 442.1 uF. The supplier we are buying from did the quality analysis over a week period and from the harmonic profile decided to tuned to the 3.78 th harmonic (226.8Hz), which is a value that's pretty standard I guess. After the line reactor is added in the system, the capacitor value is dropped to 411.2 uF and the reactor value is 1.1979mH (7% reactor). The quality factor Q being used in all of this is 40. Now what I am wondering is how come the capacitor value changes after the line reactor is added and how is it being determined? And what values are imposed in all of this? Is the quality factor something determined from the harmonic profile of our load and how is it being applied to our calculations? Any information, formulas and theory on how to make sense out of all of this would be greatly appreciated! Thank you very much for your help!!