Non-Contact Voltage Sensor Using Differential Electrodes
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Solution Overview
Problem
Existing voltage sensors for line-mounted power line monitors require connection to earth-ground or a known voltage, posing safety hazards and interference issues, especially in high-energy distribution feeder lines where accurate voltage measurement is crucial but challenging due to proximity of adjacent energized conductors.
Innovation Solution
A voltage sensor system using two electrodes with different diameters and widths, positioned around a conductor without physical contact, and a differential amplifier circuit to measure voltage by differentiating charge pickup, effectively canceling out interference from nearby conductors while avoiding ground connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage sensor requires connection to earth-ground or a known voltage, then the voltage measurement can be obtained using conventional sensors, but safety hazards arise due to high energy levels in distribution feeder lines
Solution Approach 1:
The patent introduces an intermediary approach by using a voltage sensor that couples capacitively to the conductor without requiring a direct ground connection. The sensor uses a known voltage reference (such as a voltage divider network) as an intermediary to enable measurement while maintaining safety isolation from the high-energy conductor.
Solution Approach 2:
The patent replaces the mechanical/electrical connection system (direct ground connection) with an electromagnetic field-based measurement system. The voltage sensor measures voltage through capacitive coupling and electric field interaction, eliminating the need for physical ground connection and thereby removing the safety hazard associated with direct contact with high-energy conductors.
2Measurement precision
If a voltage sensor connects to earth-ground, then voltage measurement is possible, but interference from adjacent energized conductors increases due to proximity in distribution feeders
Solution Approach 1:
The patent applies local quality by designing the voltage sensor with spatially differentiated electrode configurations. The sensor uses multiple electrodes at different positions and potentials around the conductor, with each electrode having a specific role in the measurement process. This local differentiation enables the sensor to distinguish between the target conductor's voltage and interference from adjacent conductors.
Solution Approach 2:
The patent implements feedback mechanisms through the differential amplifier circuit that processes signals from multiple electrodes. The system continuously monitors and adjusts the measurement based on the voltage differences between electrodes, using feedback to cancel out interference from adjacent conductors and maintain accurate measurement of the target conductor's voltage.
3Measurement precision
If transmission line voltage sensors are used on distribution feeder lines, then voltage measurement is possible, but calibration accuracy is compromised due to closer spacing of phases
Solution Approach 1:
The patent applies parameter changes by adapting the sensor design specifically for distribution feeder conditions. The voltage sensor uses modified electrode geometries and capacitance values that are optimized for the closer phase spacing in distribution feeders compared to transmission lines. The differential amplifier circuit is configured with specific gain and frequency response parameters that account for the different electrical characteristics of distribution feeder lines.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate voltage measurement in high-energy distribution feeder lines by minimizing interference from adjacent conductors, ensuring safety and precision in energy and power parameter determination without the need for ground connection.
Implementation Method 1
The voltage sensor system uses two electrodes with different diameters and widths, positioned around a conductor without physical contact, and a differential amplifier circuit to measure voltage by differentiating charge pickup
Implementation Method 2
measure voltage by differentiating charge pickup, effectively canceling out interference from nearby conductors
Data Source
AI summary
A system and device for measuring voltage in a conductor having a voltage provides a first electrode surrounding and spaced from the conductor, and a second electrode surrounding and spaced from both the conductor and the first electrode such that there is no contact between the conductor and the electrodes or between the first and second electrodes. The first electrode is connected to a first input of a differential amplifier circuit and the second electrode is connected to the other input of the differential amplifier circuit. The output of the differential amplifier circuit provides a voltage signal in proportion to the voltage of the conductor, thus providing a non-contact means for measuring the voltage of a conductor without requiring a connection to ground while simultaneously providing a high level of rejection of external interference.