Self-Compensated Electrical Sensor with Dual Capacitive Dividers
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Solution Overview
Problem
Capacitive voltage sensors are susceptible to irreversible degradation of dielectric material over time and inaccuracies due to external electrical fields, leading to reduced accuracy in power generation, transmission, and distribution systems.
Innovation Solution
An electrical sensor with a two-capacitive divider arm and concentric conductors protected by concentric shields, combined with a compensating circuit, maintains accuracy by compensating for dielectric permittivity deviations and external electrical interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single capacitive divider is used to measure voltage, then the device complexity is low, but measurement precision deteriorates due to dielectric degradation and external electrical field interference
Solution Approach 1:
The voltage measurement system is divided into two separate capacitive dividers: a primary capacitive divider for voltage division and a secondary capacitive divider for compensation. Each divider has its own output, allowing independent measurement and compensation functions. This segmentation enables the system to achieve high measurement precision by separating the measurement function from the compensation function, while managing device complexity through modular design.
Solution Approach 2:
The secondary capacitive divider acts as an intermediary compensation mechanism that measures the same voltage signal but with different dielectric characteristics. By comparing the outputs of both dividers, the system can identify and compensate for dielectric degradation effects. The concentric shields serve as intermediaries to block external electrical field interference from affecting the measurement.
2Reliability
If dielectric material is used in capacitive dividers, then the sensor can operate at high voltages, but reliability deteriorates due to irreversible degradation over time
Solution Approach 1:
The system uses two capacitive dividers with different dielectric materials or different dielectric configurations. By monitoring the output signals from both dividers, the system can detect changes in dielectric properties over time. The compensating circuit adjusts the measurement based on these parameter changes, maintaining reliability even as the dielectric material degrades over its service life.
Solution Approach 2:
The output of the secondary capacitive divider is fed into a compensating circuit that processes both divider outputs. This feedback mechanism continuously monitors the voltage measurement and adjusts for dielectric degradation effects by comparing the two measurement paths. The compensating circuit uses the differential information to correct measurement drift, extending the effective reliability period beyond the natural dielectric service life.
3Measurement precision
If concentric shields are added to protect from external electrical fields, then measurement precision improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The sensor employs a nested concentric conductor structure where multiple conductors are arranged in nested cylindrical layers, each surrounded by its own dielectric material and shield. This nesting approach achieves comprehensive electrical field shielding and measurement precision while managing manufacturing complexity through a systematic layered construction process that can be implemented using standard high-voltage sensor manufacturing techniques.
4Measurement precision
If a two-capacitive divider system is implemented, then compensation for dielectric degradation is achieved, but loss of energy increases due to additional capacitive components
Solution Approach 1:
The system implements a two-capacitive divider configuration where the secondary divider provides compensation functionality. While this does increase energy loss compared to a single divider, the partial action principle is applied by optimizing the capacitance values and dielectric materials to minimize unnecessary energy dissipation. The compensation function is achieved with minimal excess energy consumption by carefully selecting component parameters.
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 sensor achieves a metering class accuracy of 0.2% to meet IEC standards, providing stable voltage measurements across varying temperatures, thus enhancing the reliability of power systems.
Implementation Method 1
a first inner conductive layer configured to form a first capacitive coupling with the electrode
Implementation Method 2
a second inner conductive layer configured to form a second capacitive coupling with the conductive material of the intermediate tubular body
Implementation Method 3
The concentric conductors are protected from external electrical fields by concentric shields
Data Source
AI summary
An electrical sensor may include an electrode. The electrical sensor may include a first capacitive divider electrically coupled between the electrode and ground, the first capacitive divider including a first output. The electrical sensor may include a second capacitive divider electrically coupled between the first output and ground, the second capacitive divider including a second output. The electrical sensor may include a compensating circuit configured to receive, as inputs, the first output and the second output and to output a compensated voltage signal corresponding to a voltage of the electrode.