How to ensure EMC of low-voltage voltage sampling in intelligent low-voltage monitoring units?

Low-voltage sampling EMC assurance considers isolation and noise suppression. A resistor divider plus isolation amplifier scheme is adopted. The voltage divider resistors use high-voltage thin-film resistors with an accuracy of 0.5%. The isolation amplifier is an ISO7240C with an isolation voltage of 3kVrms. An RC filter (10kΩ + 1nF) is added to the sampling input. PCB design: 10mm slots are used between the high-voltage and low-voltage sections. Coaxial cables are used for the sampling lines. This design achieves a voltage sampling accuracy of 0.5%, a common-mode rejection ratio greater than 100dB, and meets the surge test requirements of IEC 61869 and IEC 61000-4-5.