How to control EMI in the arc extinguishing circuit of a power FTU?

The arc-extinguishing circuit generates strong electromagnetic interference, requiring special control. Multiple suppression methods are employed: an RC absorption circuit (100Ω + 10nF/1000V) is connected in parallel across the circuit breaker contacts to absorb arc energy. A PBZ3216E120Z0T ferrite bead (120Ω@100MHz) is connected in series with the arc-extinguishing coil. The entire arc-extinguishing chamber is fitted with a 1.5mm thick metal shield made of electrical pure iron. The shield is grounded at a single point with a 6mm² grounding wire. An independent isolation transformer is used for the arc-extinguishing circuit power supply. Through this control, the arc-extinguishing EMI is reduced by more than 50dB, radiated emissions meet the EN55032 Class A limits, and pass the IEC 61000-4-4 EFT 4kV test.