Axially Overlapping Electrodes for High-Voltage Sensor Insulator
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Solution Overview
Problem
Existing high-voltage sensors require large, expensive insulators to maintain accurate voltage measurements, which limits their attractiveness due to the need for large corona rings and high electric field strengths, especially at the outer surface of the insulator.
Innovation Solution
A high-voltage sensor design featuring an insulator with a sensing cavity and conductive electrodes that are capacitively coupled and axially overlapping, allowing for a slender, lightweight insulator with controlled electric field distribution, reducing the need for large insulators and minimizing peak electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single long BGO crystal is used to measure full line voltage, then the sensor signal corresponds to the true voltage (line integral of electric field), but the electric field strengths at the crystal become very high requiring large hollow insulators with SF6 gas pressure
Solution Approach 1:
The patent divides the single long crystal into multiple smaller electro-optical crystals (first, second, and third crystals) arranged in series within the insulator. Each crystal measures the electric field at its specific location, and the sum of these local measurements approximates the total voltage. This segmentation reduces the electric field strength at each crystal location, allowing for a more compact insulator design without sacrificing measurement accuracy.
2Volume of stationary object
If several small electro-optical crystals are used at selected positions, then the field strengths are significantly lower and nitrogen insulation at atmospheric pressure is sufficient, but the sensor measures only local field strengths requiring permittivity-shielding to avoid approximation errors
Solution Approach 1:
The patent applies permittivity-shielding specifically at the locations of the electro-optical crystals to control and stabilize the electric field distribution in their immediate vicinity. This localized application of permittivity-shielding ensures that each crystal measures the electric field under controlled conditions, improving the accuracy of the local field measurements and reducing approximation errors when summing to obtain the total voltage.
3Volume of stationary object
If voltage is partitioned among several quartz crystals with piezo-electric deformation, then electric field strengths are reduced allowing slender insulators, but relatively large corona rings are required and enhanced electric field strengths occur at the outer surface near electrode positions
Solution Approach 1:
The patent uses permittivity-shielding to control and redistribute the electric field in a way that converts the potentially harmful enhanced field strengths at electrode locations into a more uniform field distribution. By strategically placing permittivity-shielding elements, the patent redirects the electric field lines to avoid concentrated stress points, thereby reducing corona discharge risk and preventing electric breakdown while maintaining the compact insulator design.
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
The design achieves a uniform voltage drop along the insulator's surface and within the sensing cavity, reducing the risk of electric breakdown and enabling smaller, cost-effective insulators while maintaining accurate voltage measurement.
Implementation Method 1
Optical high-voltage sensors often rely on the electro-optic effect (Pockels effect) in crystalline materials such as Bi4Ge3O12 (BGO)
Implementation Method 2
A plurality of conductive electrodes are arranged in the insulator. The conductive electrodes are mutually separated by the insulating material and capacitively coupled to each other
Data Source
AI summary
A voltage sensor includes an insulator with mutually insulated electrodes embedded therein. The electrodes are coaxial and cylindrical and overlap axially along part of their lengths. They are mutually staggered and control the surfaces of electric equipotential such that there is a substantially homogeneous electric field outside the insulator and a substantially homogeneous but higher field within a sensing cavity within the insulator. A field sensor is arranged within the sensing cavity to measure the field. This design allows for the production of compact voltage sensors for high voltage applications.