Switchgear Connection Interface for Accurate Busbar Voltage Sensing
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Solution Overview
Problem
Existing high-voltage switchgear measurement systems, such as metering cells, are not sufficiently accurate for smart grid requirements, are bulky, and difficult to install, especially in retrofits, due to issues like ferroresonance, saturation, and measurement inaccuracies caused by variations in permittivity and dissipation factor.
Innovation Solution
A modular high-voltage switchgear panel with a measuring device featuring a frustoconical cavity and insulating casing, connected via a symmetrical connecting sleeve, ensures precise and efficient measurement of voltage and temperature, with a compact design suitable for easy integration into existing installations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metering cells with inductive voltage transformers are used for voltage measurement, then voltage measurement capability is provided, but measurement accuracy deteriorates due to ferroresonance and saturation issues
Solution Approach 1:
The patent extracts the measurement function from a separate metering cell and integrates it directly into the connection interface of the switchgear unit. This eliminates the need for a dedicated metering cell with inductive voltage transformer, thereby avoiding ferroresonance and saturation issues while maintaining measurement capability through capacitive sensors integrated at the connection point
Solution Approach 2:
The patent changes the measurement principle from inductive transformation to direct capacitive sensing. By using capacitive sensors that measure voltage directly without transformation, the system avoids the ferroresonance and saturation problems inherent in inductive voltage transformers, significantly improving measurement accuracy and reliability
2Adaptability or versatility
If metering cells are installed for voltage measurement, then measurement function is added, but device size increases making installation difficult in existing installations
Solution Approach 1:
The patent merges the measurement function with the existing connection interface structure. The capacitive sensors are integrated directly into the connection interface where busbars connect, eliminating the need for a separate metering cell. This combination provides voltage measurement capability while occupying minimal space, enabling installation in existing switchgear units during retrofit scenarios
Solution Approach 2:
The connection interface is designed to serve multiple functions: electrical connection, mechanical support, and voltage measurement. By integrating capacitive sensors into the connection interface, the same structural element performs both connection and measurement tasks, eliminating the need for additional dedicated measurement equipment and reducing overall device volume
3Measurement precision
If capacitive sensors are used at connecting sleeves for measurement, then measurement capability is provided, but measurement accuracy deteriorates due to variations in permittivity and dissipation factor
Solution Approach 1:
The patent introduces a reference capacitor with known and stable electrical characteristics as an intermediary element. By comparing the measurement capacitor's characteristics against this stable reference, the system compensates for variations in permittivity and dissipation factor, maintaining measurement accuracy despite environmental changes in temperature and voltage
Solution Approach 2:
The patent implements a measurement system that continuously monitors the electrical characteristics of capacitive sensors and compares them against reference values. When variations in permittivity or dissipation factor are detected, the system adjusts measurements accordingly, providing feedback-based compensation that maintains accuracy despite environmental variations
Data Source
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Figure 3~5
AI summary
Measuring device (20) adapted to be connected to a conductive bar (8) of a high voltage switchgear cell (10), the measuring device comprising a casing (21) made of insulating material, an electric circuit (22) measurement integrated inside the casing, a power conductor (23) connected to the electrical circuit (22). The envelope (21) has a cavity (26) of frustoconical shape, the power conductor (23) protruding from the envelope at the center of the frustoconical cavity, and in that the frustoconical cavity (26) is adapted to cooperate with a connection sleeve (30) of a connection interface (15) of the apparatus cell (10), so as to electrically connect the power conductor (23) to the conductive bar.