Abstract: This paper mainly introduces the formation, source, and path of interference in frequency converters, as well as countermeasures to prevent interference and several effective anti-interference measures in practical applications. Keywords: frequency converter; electromagnetic interference; anti-interference I. Sources of frequency converter interference The first is interference from the external power grid. Harmonic interference in the power grid mainly interferes with the frequency converter through the power supply of the frequency converter. There are a large number of harmonic sources in the power grid, such as various rectifiers, AC/DC switching equipment, electronic voltage adjustment equipment, nonlinear loads and lighting equipment. These loads cause waveform distortion of voltage and current in the power grid, thereby causing harmful interference to other equipment in the power grid. If the power supply of the frequency converter is not treated after being interfered with by the polluted AC power grid, the power grid noise will interfere with the frequency converter through the power supply circuit. The interference of the power supply to the frequency converter mainly includes: (1) overvoltage, undervoltage, instantaneous power failure; (2) surge, drop; (3) voltage spike; (4) radio frequency interference. 1. Interference from Thyristor Converter Equipment to Frequency Converters When there are large-capacity thyristor converters in the power supply network, the thyristors are always conducting for a portion of each phase's half-cycle, which can easily cause voltage dips and severe waveform distortion. 2. Interference from Power Compensation Capacitors to Frequency Converters Many users use centralized capacitor compensation in substations to improve the power factor. During the transient process of switching the compensation capacitors on or off, the network voltage may experience very high peak values. This can potentially cause the inverter's rectifier diodes to break down due to excessive reverse voltage. [b][align=center]For more details, please click: Interference Problems and Countermeasures in Frequency Converter Applications[/align][/b]