How to isolate the strong and weak current wiring in a power FTU?

Strong and weak current isolated cabling prevents electric and magnetic field coupling. A zoning, layering, and shielding strategy is employed.

PCB Zoning: Strong current areas (power supply, motor drive) and weak current areas (sampling, control) are placed on opposite sides of the board, with a spacing greater than 20mm, and a 5mm groove filled with insulating material in between.

Cabling Layering: Strong current runs on the top and bottom layers, and weak current runs on the inner layers, with a ground plane for isolation in between.

Cable Isolation: Strong and weak current wires are run in separate cable trays, with a spacing greater than 150mm, and cross perpendicularly when crossing.

Shielding Measures: Shielded twisted-pair cables are used for weak current signal lines, and the shielding layer is grounded at a single point.

Through this isolated cabling, coupling interference is reduced by more than 40dB, meeting the EMC requirements of IEC 61800-3 industrial environments.