How to avoid ground loop interference in intelligent low-voltage monitoring units?

To avoid ground loop interference, isolation technology and single-point grounding are employed. The communication interface uses an ADUM1410 digital isolator with an isolation voltage of 3kVrms. Analog sampling utilizes an ISO7240C isolation amplifier. The power system uses a DC-DC isolation module WRB2405S-3W with an isolation voltage of 1500VDC. Grounding design: A star-connected single-point grounding is adopted, with all analog grounds, digital grounds, and power grounds connected to the chassis grounding point through a 0Ω resistor. The chassis grounding uses low-impedance copper tape with a grounding resistance of less than 0.05Ω. The cable shielding is single-point grounded at the monitoring unit end, while the sensor end remains unconnected. This solution eliminates ground loop current, improves the common-mode rejection ratio to over 100dB, and meets the IEC 61000-4-8 power frequency magnetic field immunity test requirements.