How to avoid ground loop interference in the concentrator?

When a concentrator is interconnected with a remote data acquisition unit or multiple devices, ground loops can form due to potential differences at the grounding points. These loops can generate power frequency or high frequency circulating currents on the signal ground line, interfering with the acquired signal. The key to avoiding ground loops is to cut off the circulating path or eliminate the potential difference. For communication interfaces (such as RS485), use isolated transceivers (such as ADM2587E) with an isolation withstand voltage of 2.5kVrms to completely disconnect the ground connection. For analog sampling lines, use differential input instrumentation amplifiers (such as INA188), whose high common-mode rejection ratio (CMRR>120dB) can suppress ground noise. The cable shield should use single-point grounding, typically connected to the chassis ground at the concentrator end and floating at the remote end. If the system requires multi-point grounding, a common-mode choke CMZ2012A-900T (90μH) should be connected in series in the shield to suppress circulating currents. Simultaneously, ensure all devices are connected via equipotential bonding conductors. With this treatment, the noise voltage induced by the ground loop on the signal line can be less than 1mV, ensuring acquisition accuracy.