How can a power FTU (Fault Tolerancing Unit) resist strong electrical interference in low-voltage measurements?

For low-voltage electrical measurement, multiple isolation and shielding are employed to resist strong electrical interference.

Signal isolation: An ISO7240C isolation amplifier is used, with an isolation voltage of 3kVrms.

Power isolation: A DC-DC module WRB2405S-3W is used.

Spatial isolation: The PCB spacing between low-voltage and high-voltage circuits is greater than 20mm, with a slot filled with insulating material in between.

Shielding measures: A 0.8mm thick metal shield is added to the low-voltage section. Shielded twisted-pair cables are used, with the shielding layer grounded at a single point.

Through this design, the strong electrical interference suppression ratio is greater than 100dB, and the accuracy of low-voltage electrical measurement remains at 0.1 class, meeting the EMC requirements of IEC 61800-3 for industrial environments.