The harm of harmonics in the principle of induction melting furnace

With the development of power electronics technology, the application of induction melting furnaces is becoming more and more extensive, and the harm of high-order harmonics generated by the rectifier circuit of induction melting furnaces to the power grid cannot be ignored. These include:

1) Harmonics cause additional harmonic losses to the components in the power grid, reducing the efficiency of power generation, transmission and electrical equipment. A large number of third harmonics flowing through the neutral line will cause the line to overheat and even cause a fire;

2) Harmonics affect the normal operation of various electrical equipment, causing mechanical vibration, noise and overheating of the motor, causing serious local overheating of the transformer, overheating, aging of the insulation, shortening the life of the capacitor, cable and other equipment, and even damage;

3) Harmonics will cause local parallel resonance and series resonance in the power grid, which will amplify the harmonics and cause serious accidents;

4) Harmonics will cause interference to the adjacent communication system, the lighter ones will produce noise and reduce the communication quality, and the more serious ones will cause the loss of information and make the communication system unable to work normally;

5) Harmonics can cause malfunctions of relay protection and automatic devices, and make the measurement of electrical measuring instruments inaccurate.

    Because the harmonic voltage and harmonic current in the public power grid cause great harm to the electrical equipment and the power grid itself, many countries in the world have issued national standards to limit the harmonics of the power grid, and authoritative organizations formulate regulations to limit the harmonics. Most of the harmonic standards formulated by countries in the world are relatively close.