Calibrated Single-Contact Voltage Sensor for High-Voltage Monitoring Applications

TL;DR

This paper presents a calibrated single-contact voltage sensor capable of accurately measuring high-voltage AC lines remotely, using a capacitive divider and calibration methods to ensure precision without detailed conductor geometry knowledge.

Contribution

The work introduces a novel single-contact voltage sensor with calibration techniques that enable accurate high-voltage measurements without precise conductor geometry, supported by extensive simulations and experimental validation.

Findings

Achieves 10% line voltage measurement accuracy with 1% calibration precision.

Validates sensor performance up to 7.5 kVrms line voltage.

Design effectively compensates for conductor spacing and height variations.

Abstract

A single-contact voltage sensor designed for accurate measurements of ac voltages across a pair of conductors is described. The sensor design is motivated by remote monitoring applications where accurate voltage measurement of high-voltage transmission lines is required. The body of the sensor is electrically and mechanically attached to a single conductor: either the neutral or high-voltage conductor. A capacitive sensing plate attached to the sensor creates a capacitive voltage divider using the stray capacitance to the non-contacted line. A very high-impedance buffer is used to measure the voltage across the divider output and estimate the line voltage. An important part of the work includes a method of calibrating the sensor such that blind voltage measurements can be made without knowing the exact geometry of the conductors. Other important aspects of the design include a two-stage voltage divider for retaining accuracy and increasing the voltage range of the sensor. The work is supported by extensive numerical simulation models which were used to determine the optimum design for the sensing plate and to evaluate the sensitivity to different configurations including conductor spacing and the height above ground. For calibration values which are accurate to 1%, the line voltage can be measured with an accuracy of 10%. The paper describes the theory, design, and experimental verification of the sensor up to a line voltage of 7.5 kVrms.