How should the shielding of the communication cable for the power measurement switch (PMS) be handled?

The shielding of PMS communication cables (RS485, CAN, Ethernet, etc.) is crucial for ensuring communication quality; improper shielding can introduce interference or radiated noise. The basic principle is that the shielding layer must be reliably grounded at the PMS device end, with the grounding point being the chassis ground (PE). The connection method must be 360° crimping; if using metal cable gland or shielding clips, pigtail connection is strictly prohibited. At the remote device end, the grounding situation determines the appropriate method: if the remote device is well grounded and has a small potential difference with the PMS ground, the shielding layer should also be grounded at the remote end (grounded at both ends); otherwise, it should be floating at the remote end (grounded at one end) to avoid ground loops.

In environments with severe high-frequency interference, even with grounding at both ends, it is recommended to connect a ferrite core (PBZ1608E600Z0T) in series in the shielding layer to suppress low-frequency circulating currents. The shielding layer should enter the PMS along with the communication signal line and immediately pass through filtering and protection circuitry at the entry point. The cable itself should be shielded twisted-pair cable with a small twisted-pair pitch. With proper handling, communication cables can resist external interference and reduce their own radiation, thus meeting the EN 55032 radiated emission requirements.