How should the shielding of the power cable of the power measurement switch (PMS) be grounded?

If the input and output power cables of the PMS (such as main power lines and motor drive lines) have shielding layers, proper grounding can constrain their electric and magnetic field radiation, reducing external interference and internal disturbance. For three-phase four-wire systems (L1, L2, L3, PE) or single-phase power lines, if shielded power cables are used, the shielding layer should be grounded at both ends, i.e., both the PMS end and the power supply end (or load end) should be grounded. This is because the power line frequency is low (50Hz), and grounding at both ends will not form a significant ground loop and can ensure the shielding effect. When grounding, the shielding layer should be connected in a 360° circle through cable clamps or dedicated grounding clamps, and the grounding wire should be short and thick (cross-sectional area not less than 1/2 of the phase wire). Inside the PMS, the grounding point of the shielding layer should be selected on the grounding terminal of the power filter or the dedicated grounding post of the chassis. If the cable is very long (>30m), consider adding a grounding in the middle. For motor cables output by the frequency converter, shielding is particularly important, and both ends must be grounded to suppress high-frequency common-mode current. Proper shielding and grounding can reduce radiated interference from power cables by more than 15 dB.