How should the shield of the concentrator sampling cable be grounded?

The grounding method of the shielding layer of the concentrator's external sampling cable (connecting to the CT/VT or sensor) is crucial for suppressing interference. The correct grounding principle is "single-point grounding, connected to a clean ground." Typically, the shielding layer should be grounded at the concentrator equipment end, specifically connected to a "clean analog ground" (AGND) at the same potential as the sampling circuit reference, or directly connected to the chassis ground (PE), depending on the system grounding strategy. If the concentrator's internal analog ground is isolated from the chassis ground (connected via an inductor or resistor), the shielding layer should be connected to the chassis ground. Connections must use a 360° crimping method, such as using a metal cable gland or shielding clip. "Pigtail" connections are strictly prohibited. At the sensor end, the shielding layer should be left unconnected unless the sensor housing is grounded. For long cables or environments with severe high-frequency interference, the shielding layer at the concentrator end can be grounded through a capacitor (e.g., 1nF).