Three propagation paths of electromagnetic interference in frequency converter systems
The propagation path of electromagnetic interference in frequency converter systems: Frequency converters can generate high-power harmonics and have strong interference with other equipment in the system. Its interference channels are the same as general electromagnetic interference channels, including electromagnetic radiation, circuit coupling, induction coupling, etc.
1. Electromagnetic radiation
The frequency converter is a non-linear load for the power grid, and the harmonics it generates cause harmonic interference to other electronic and electrical equipment connected to the same power grid. When the metal casing of the frequency converter has gaps or holes, the radiation intensity is related to the wavelength of the interference signal. When the size of the holes is close to the wavelength of the electromagnetic wave, an interference radiation source will form and radiate to the surrounding areas. Metal objects in the radiation field may also form secondary radiation. Similarly, external radiation from the frequency converter can also interfere with its normal operation. Dual Testing Functions: the EMF meter can accurately detect and measure the electric field radiation and magnetic field emission at the same time. It also can measure the environment temperature(℃/℉).
2. Circuit coupling
Electromagnetic interference can not only be emitted outward through the wires connected to it, but can also be transmitted into other circuits through impedance coupling or grounding loop coupling. A typical transmission route is that the interference signal generated by the frequency converter connected to the industrial low-voltage network can enter the medium voltage network along the distribution transformer, and ultimately enter the civilian low-voltage distribution network along other distribution transformers, making electrical equipment connected to the civilian distribution bus a remote victim.
3. Inductive coupling
When the input or output circuit of the frequency converter is very close to the circuits of other devices, the high-order harmonic signal of the frequency converter can be coupled to other devices through induction. The current interference signal mainly propagates through electromagnetic induction, while the voltage interference signal mainly propagates through electrostatic induction.
