How should the shield of the sampling cable for a power FTU be grounded?

The grounding method of the sampling cable shield affects the anti-interference effect. A single-point grounding principle is adopted: the shielding layer is grounded at the FTU end, and the sensor end is left floating. Grounding method: 360° crimping to the housing via a shielded connector, or connection via the shielding ground pad on the PCB. For high-frequency interference, a 100nF/2kV capacitor can be connected in parallel at the grounding end. In multi-core cables, each twisted pair is individually shielded, and the overall shielding layer is grounded. The grounding resistance is less than 0.1Ω. With proper grounding, the shielding effectiveness is greater than 40dB, and common-mode interference is reduced by more than 30dB, meeting the IEC 61000-4-6 conducted immunity test requirements.