Rogowski Coil and Capacitive Divider Switchgear Sensing
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Solution Overview
Problem
Existing medium voltage switchgear systems lack compact, cost-effective, and self-monitoring digital sensors for accurately measuring current and voltage, relying on bulky and expensive analog transformers that are not inherently self-monitoring and require additional digital conversion.
Innovation Solution
Integration of Rogowski coils and Capacitive Voltage Dividers into the Stationary Primary Disconnect Assembly of switchgear, combined with an integrated circuit for digitization and time stamping, to provide a lightweight, accurate, and self-monitoring system for current and voltage measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional current transformers and voltage transformers are used for sensing, then measurement reliability is maintained, but device weight and volume increase significantly
Solution Approach 1:
The patent replaces traditional electromagnetic transformers (mechanical/electromagnetic systems) with electronic sensing circuits including Rogowski coils for current sensing and capacitive voltage dividers for voltage sensing. These electronic components convert physical quantities directly into digital signals through integrated circuits, eliminating the need for heavy iron cores and copper windings while maintaining measurement accuracy and reliability
Solution Approach 2:
The invention changes the operating parameters of the sensing system by transitioning from analog transformer outputs to digital signal outputs. The integrated circuits directly convert sensed physical quantities into digital signals with time stamps, fundamentally changing the signal parameter from analog to digital domain, which enables lighter weighting while preserving measurement integrity
2Measurement precision
If traditional voltage transformers are used, then voltage measurement accuracy is achieved, but device cost and complexity increase
Solution Approach 1:
The patent merges the voltage sensing function and digital conversion function into a single integrated capacitive voltage divider circuit with embedded integrated circuit. This combination eliminates the need for separate analog-to-digital converter modules and reduces the number of discrete components, thereby simplifying the overall system architecture while maintaining voltage measurement precision
Solution Approach 2:
The invention replaces complex electromagnetic transformation systems with simpler electronic sensing circuits. The capacitive voltage divider uses basic electronic components (capacitors, resistors) and integrated circuits to achieve voltage sensing and digital conversion, significantly reducing system complexity compared to traditional voltage transformers while preserving measurement accuracy
3Reliability
If analog transformation devices are used, then signal proportionality is maintained, but device volume and handling difficulty increase
Solution Approach 1:
The patent replaces bulky analog transformation devices with compact electronic sensing circuits. The Rogowski coil and capacitive voltage divider generate analog signals that are immediately converted to digital signals by integrated circuits mounted on the same device, eliminating the need for separate transformer units and reducing overall device volume while maintaining signal fidelity
Solution Approach 2:
The invention nests the integrated circuit board within the housing of the disconnect assembly, integrating multiple functions (sensing, conversion, processing) into a single compact unit. The electronic components are arranged in a nested configuration where the circuit board is mounted inside the assembly housing, maximizing space utilization and minimizing overall device volume
4Measurement precision
If separate sensing devices are used for current and voltage, then measurement coverage is complete, but device integration and space utilization worsen
Solution Approach 1:
The patent merges current sensing (Rogowski coil) and voltage sensing (capacitive voltage divider) functions into a single integrated disconnect assembly. Both sensing circuits and their respective integrated circuit converters are mounted together on the same device, eliminating the need for separate sensing devices and reducing integration complexity while maintaining complete measurement coverage
Solution Approach 2:
The disconnect assembly is designed as a universal platform that simultaneously performs multiple functions: circuit interruption, current sensing via Rogowski coil, voltage sensing via capacitive divider, and digital signal processing. This multi-functional integration reduces the total number of devices needed while maintaining comprehensive measurement capabilities
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 solution offers a compact, cost-effective, and highly accurate digital measurement system that is self-monitoring, capable of withstanding high magnetic flux conditions, and provides real-time data streaming with enhanced reliability and reduced weight and bulk.
Implementation Method 1
Rogowski coil... provide an analog signal of the current flowing through the conductor
Implementation Method 2
capacitive voltage divider... provide an analog signal of the voltage on the conductor
Data Source
AI summary
A device for protecting, controlling, and monitoring insulated conductors comprising use of a Rogowski coil surrounding the conductor and a capacitive or similar voltage-like divider, also surrounding the conductor and connected thereto and to ground, and providing analog signals from those devices to an integrated circuit for conversion by look up tables on the integrated circuit to digital signals and then transmitting as output the digital signals to a data collector and memory device where the same are optionally time stamped and compared to one another, to a standard or to themselves at a different time for providing a mechanical, electrical or electronic signal.