Regarding harmonic control, we must first understand what is harmonic?

Harmonic term originated from acoustics. Mathematical analysis of harmonics has been laid in the 18th and 19th centuries. Fourier et al. proposed the harmonic analysis method, which is still widely used in power systems. Harmonic problems were caused in the 1920s and 1930s. People paid attention to the voltage and current waveform distortion caused by the use of static mercury arc converters in Germany. In 1945, JCRead published a paper on harmonics of converters. In the early 1950s and 1960s, due to high-voltage direct current transmission Technology Development Published a large number of papers on the harmonic problems of power systems caused by converters. Since the 1970s, due to the rapid development of power electronics technology, various power electronic devices have been widely used in power systems, industries, transportation and households. Harm caused by harmonics has become increasingly serious in the world All countries have paid full attention to harmonic issues and held many academic conferences on harmonic issues internationally. Few countries and international academic organizations have formulated standards for limiting harmonics in power systems and electrical equipment and specifying the significance of harmonic research. Harmonics are very serious Harmonics reduce the efficiency of electric energy production, transmission and utilization, make electrical equipment overheat, generate vibration and noise, shorten the service life of insulation aging, or even fail or burn out. Harmonics cause local parallel resonance or series resonance in the power system The amplification of wave content will cause capacitors and other equipment to burn out. Harmonics will also cause relay protection and automatic devices to malfunction, causing confusion in electric energy measurement. External harmonics of the power system will cause serious interference to communication equipment and electronic equipment.

How to manage harmonics? Especially in terms of power supply and motor protection, with the improvement of industrial automation and the implementation of energy saving, energy saving and consumption reduction policies, motors are rarely directly connected to the power grid for direct use, and are usually driven by frequency converters, which can flexibly Control the power and speed of the motor to meet the functional requirements, and the energy saving effect is remarkable. However, the frequency converter brings the problem of harmonic current to the power grid. No power supply company allows users to inject excessive harmonic current into the grid. The user is responsible for eliminating the harmonic current generated by the frequency converter. Use and protection of motors, MTE input reactors, output reactors, dv/dt filters and more, dV Sentry's unique design provides better load side protection against voltage spikes in AC motors, cables and drives and common-mode voltage interference.

The filter with patented design integrates common mode reduction by more than 50%, peak voltage protection and reduced rise time.