Power Quality Monitoring

▼Chapter 4Prophi ®power factor controllerApplicationsPFC systems are used to discharge unnecessarily overloaded supplysystems through inductive reactive power and to save reactiveconsumption costs. The reactive power controller is the main partof a PFC system and automatically switches capacitors steps on oroff. The Prophi ® power factor controller is suitable for use in conventionaland dynamic PFC systems. A mixed operation (hybridswitching) is possible as well.Features Automatic configurationIllustration: Reverse of Prophi ® 12RS Display of U, I, f, Q, P, S, cos-phi, uneven currentand voltage harmonics, 1-19th Display of capacitor currents Display of switching cycles per capacitor step Display of capacitor step connection time Zero voltage release within 15ms Detuning degree in % is programmable for eachstep from 0-20% Setting of discharging time for all capacitor stepsfrom 0-1200 secs Capacitor power can be individually programmedAlarm output is programmable for: Temperature sensor for ventilator control Excess temperature shutdown can be programmed Under-voltage recognition Control of external semiconductors Over voltage recognition(max. 50 switch actions per second) Under-compensation Current transformer input for ../1A and ../5A Measurement current exceeding Automatic or manual configuration Harmonic limit value Password protection Supply of effective power External target cos-phi changeover Excess temperature▼Functional principleThe single-phase electronic measuring system collects the reactive and effective current ratios of the network through the current andvoltage measurement. Using the current from one phase and the voltage from the other two phases, the reactive power controllercalculates the necessary reactive power to achieve the set target power factor. The capacitor steps are switched on or off if any differencesoccur and the reactive power controller differentiates between the switching of capacitors through contactors or thyristors. The controlthrough capacitor contactors is optimised; this means that the reactive power factor controller achieves the cos-phi target with a minimumof switching actions. The transistor outputs control the semiconductor switches for almost immediate compensation of any differences.115