The measurement is done by performing Fourier analysis to voltage and current waveforms, values of total RMS, fundamental RMS and total harmonic distortion is then calculated. Finally the fundamental component of active, reactive, apparent power and PF are all calculated. The whole measurement cycle takes about 400mSec. The measured values are available to the user on the display during the normal operation.
2- The switching program:
The PFC does not use any fixed switching program or sequence. Instead of that, it automatically detects and stores all of the connected capacitor step values. Then when a reactive compensation is desired, the PFC selects the most appropriate steps to switch in to achieve the desired PF in the least possible number of steps. Meanwhile the switching program chooses steps which are least used in order to distribute switching load among all the steps. This switching program can work with any values of capacitors in any arrangement automatically without the need of user settings.
The switching program can be manually disabled. Keeping the currently switched steps permanently switched, even if the actual power factor deviates from the target power factor. This feature is useful when the user does not need to control the power factor, but prefers to keep the measurement and warnings of the PFC active.
3- Automatic value determination of capacitors:
The PFC can automatically determine the value of a certain capacitor by monitoring the