Transmission and distribution system is running on a sine wave voltage and current waveforms with fixed-frequency . However, non-linear loads , like: thyristor, converter, electric arc furnace access system will generate a lot of seventh harmonic currents and cause voltage and current distortion of the system.
Seventh harmonic filter is he best way to eliminate seventh harmonic distortion of the power system , at the same time to generate reactive power in the fundamental frequency .
Characteristics of Seventh harmonic filters and reactive power compensation
1, the Seventh harmonic filter circuit is made of reactors serial by capacitors. Capacitor of Seventh harmonic filter generated reactive power in the fundamental frequency . the circuit design for compensation according to the power factor ; the inductance value choice of reactor is to series with the capacitor to form harmonic resonance ,so that establish a low impedance circuit to make most of the seventh harmonics inflow the filters.
2, each of seventh harmonic filters includes a electromagnetism contactor, thermal relay, reactors and capacitors. Harmonic filters are usually connected to the main distribution cabinet by fuses feeder .
3, control mothed of seventh harmonic filters and the capacitor of automatic switching can be the same: the reactive power adjusted by the automatic power factor controller .
4, seventh harmonic filters is based on the customer’s specific application requirements, using standard device to design, so that achieve the best power factor compensation and harmonic filtering characteristics through a reasonable investment .
Technical parameters
1, the system voltage: ≤ 750V
2, the filter tuned to 7th harmonic
3 Cabinet Dimensions: W × D × H (mm) 800 × 800 × 2000
4, the fundamental frequency: 50 HZ
5, the output capacity per container: about 60~300kvar
6, protection class: IP 20