How to seal the shielding at the cable inlet of the PMS (Power Measurement System) switch?

The entry point for cables into and out of the PMS chassis is the weakest link in shielding and must be effectively shielded and sealed to prevent the "pigtail effect." The standard practice is to use high-shielding cable grands (cable connectors) or filter connectors. For shielded cables, cable grands with metal sheaths and flexible toothed washers should be selected. During installation, tighten the grands to deform the washers and achieve 360° circumferential contact with the cable shielding layer, while ensuring good contact between the grand shell and the metal surface of the chassis opening.

For multi-core unshielded cables, through-panel connectors with filtering capabilities (such as D-Sub with filtering) should be used, with the connector shell connected to the chassis panel at low impedance. If there are many cables, they can be centrally connected through a high-shielding junction box (grounded metal box). It is absolutely forbidden to directly pass cables through a simple plastic hole or use non-metallic cable ties for securing them. After all entry point treatments are completed, a shielding effectiveness tester (such as the GTEM chamber method) can be used for evaluation, aiming to control the leakage at the cable entry point to a level at least 10 dB lower than the radiation from the chassis itself.