How can a concentrator resist strong electrical interference when measuring weak electrical signals?

Microamplitude/millivolt level low-voltage signals in concentrators are easily submerged in high-voltage environments, making anti-interference design crucial. The core strategy is "isolation, shielding, filtering, and differential."

Isolation: Use isolation amplifiers or isolated ADCs.

Shielding: Place the low-voltage measurement circuitry in an independent metal shielded box with proper grounding; use double-shielded sampling lines, with the inner shield connected to signal ground and the outer shield connected to chassis ground.

Filtering: Implement multi-stage filtering before the signal enters the amplifier, including a common-mode inductor CMZ2012A-900T, RC low-pass filter, and software digital filter.

Differential Transmission: Employ differential signals and select a high CMRR instrumentation amplifier.

PCB Design: Completely cover the low-voltage area with a ground plane and surround it with a guard ring.

Power Supply: Provide an independent, clean, linear power supply for the low-voltage circuitry.

Through system design, the low-voltage measurement system can operate stably at a distance of 10cm from high-voltage cables, with a signal-to-noise ratio greater than 60dB.