# Reference High-Voltage Sensing Chain for the Assessment of Class 0.1-WB3 Instrument Transformers in the Frequency Range up to 150 kHz According to IEC 61869

## TL;DR

This paper introduces a high-voltage sensing system for testing instrument transformers up to 150 kHz, ensuring compliance with IEC 61869 standards.

## Contribution

A modular reference sensing chain is developed for Class 0.1-WB3 transformers with dual paths for harmonic and fundamental frequency measurements.

## Key findings

- The sensing chain achieves compliance with IEC 61869 standards for Class 0.1-WB3 transformers up to 150 kHz.
- The dual-path design improves signal-to-noise ratio for low-level harmonic components.
- The system architecture allows future extension to 500 kHz for high-frequency power quality analysis.

## Abstract

This paper presents the development and characterization of a reference high-voltage sensing chain for the calibration and conformity assessment of instrument transformers with Class 0.1-WB3, in the extended frequency range up to 150 kHz, according to IEC 61869. The sensing chain, composed of a high-voltage divider, precision attenuators and high-pass filters, has been specifically developed and characterized. The chain features two parallel measurement paths: the first path, comprising the high-voltage divider and attenuator, is optimized for measuring the fundamental frequency superimposed with high-amplitude harmonics; the second path, consisting of the high-voltage divider followed by a high-pass filter, is dedicated to measuring very-low-level superimposed harmonic components by enhancing the signal-to-noise ratio. These two paths are integrated with a digitizer to form a complete and modular measurement chain. The expanded uncertainty of measurement has been thoroughly evaluated and confirms the chain’s ability to support assessment of instrument transformers with Class 0.1-WB3 compliance. Additionally, the chain architecture enables a future extension up to 500 kHz, addressing the growing need to evaluate instrument transformers under high-frequency power quality disturbances and improving the sensing capability in this field.