WHAT ARE ACTIVE HARMONIC FILTERS?

Many modern electrical and electronic products incorporate rectifiers, which take a non-linear current from the power supply and set up repetitive waveforms with different harmonic components.

Each type of device will produce a characteristic harmonic spectrum and a complementary voltage distortion spectrum. These can have a number of unwanted effects, including conductors overheating, circuit breakers tripping, fuses blowing, insulation failure, malfunctioning micro-processor-based equipment, flickering lighting and torque pulsations in motors.

The solution is to use an ABB Power Quality Filter (PQF), which has an unprecedented ability to greatly reduce from the network, perform smooth reactive compensation and balance loads to reduce neutral to earth voltages in fourwire systems.

the PQF is not affected by large network impedance changes caused by, for example, paralleling sources or switching between mainssupply and generator operations. It also helps businesses meet international guidelines such as G5/4 and IEEE519.

It monitors the line current in real time and processes the measured harmonics as digital signals in a high power, multi digital signal processor-based system. The digital controller then generates pulse width modulator signals that inject harmonic currents with theopposite phase to the components that need to be filtered. The PQF also offers communication facilities, with options ranging from several digital I/O contacts to an optional Modbus RTU interface.