Encoded Sensors and Analog Sensors in High-Voltage Testing Applications

Abstract

High-voltage testing is an essential part of testing the insulation of power equipment. Encounter persistent trouble with much strong electromagnetic interference (EMI>=120dBμV/m), much long distance cabling(>50m), quite strict many channel synchronization precision(\<5ns), difficulty in catching high frequency abrupt signals from partial discharge(PD). Based on the real world measurement data collected from six UHV test bases in China from 2024 to 2025, this paper sets up a four-dimensional quantitative evaluation model including SNR, amplitude relative error εa, temporal jitter Δtj i t t e r, and temperature drift coefficient αt to comprehensively compare the encoded and analog sensors (RS-485 and fiber optic CAN types) and analog sensors (passive dividers, Rogowski coils, etc.) under power-frequency withstanding, lightning impulse (1.2/50 μs), switching impulse (250/2500 μs), and PD testing conditions. Sensors with codes do a better job of EMI resistance, thermal stability - α t = 12ppm / °C as well as faraway signal transmission reliability, synchronization precision (+ - 0.43ns). There's no way to replace analog sensors for PD pulse front edge fidelity, since their bandwidth is up to 150 MHz. To solve this complementarity, we put forward the "primary-auxiliary collaborative" hybrid sensing architecture: the encoded sensors serve as the primary channel for steady metrological measurement and hardware-level triggering; high-speed analog front-ends are used as the auxiliary channel for the purpose of nanosecond-level waveform construction. Hardware timestamping in used for sub-nanosecond alignment and it connects closely with the IEEE 1588v2 time synchronization. Field validation for ±800 kV UHVDC station shows:(1)Lightning impulse peak voltage expanded uncertainty(k=2)reduces from ±3.2% to ±0.86%; (2) Compression of PD rise-time measurement error from ±1.6 ns to ±0.43 ns—a full compliance with both GB/T 16927.1–2022 and IEC 60060-1:2023