Capacitive Voltage Divider for Safe Sensor Powering

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Solution Overview

Problem

Conventional methods for measuring high-voltage power line voltages are inefficient and inaccurate, particularly in providing reliable voltage measurements for power distribution systems, as they often require direct electrical coupling with hot wires, which can be hazardous and prone to errors due to power harvesting impacts.

Innovation Solution

A capacitive voltage divider system with sensor units connected to power lines using capacitors, allowing for safe and accurate voltage measurement across a lower voltage range, enabling the measurement of electrical properties like voltage, current, and power quality, while also providing power to the sensor units through the capacitive coupling, even when no current is flowing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct electrical coupling with hot wires is used to measure voltage, then voltage measurement can be obtained, but measurement accuracy deteriorates due to power harvesting impacts and safety hazards increase

Engineering Contradiction:

Improvevoltage measurement accuracyVSAvoidsafety hazards and measurement errors

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a capacitive voltage divider as an intermediary between the high-voltage power line and the measurement device. The divider consists of two capacitors that step down the high voltage to a measurable level without requiring direct electrical coupling, thereby eliminating safety hazards and improving measurement accuracy by isolating the measurement system from power harvesting impacts

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct electrical coupling (conductive connection) with capacitive coupling. This substitution uses the electric field through capacitors rather than direct wire connections, eliminating the harmful effects of direct contact with hot wires while maintaining the ability to measure voltage accurately

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If capacitive voltage divider is used to measure voltage safely, then safety improves and measurement accuracy improves, but device complexity increases

Engineering Contradiction:

Improvesafety and measurement reliabilityVSAvoidsensor unit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The capacitive voltage divider serves multiple functions simultaneously: it provides voltage transformation for safe measurement, acts as an isolator to protect the measurement system, and can also be used for power harvesting to supply the sensor unit. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If conventional direct coupling method is used, then device complexity is low, but measurement precision deteriorates due to power harvesting impacts

Engineering Contradiction:

Improvesimplicity of coupling methodVSAvoidvoltage measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The capacitive voltage divider acts as an intermediary that decouples the measurement system from the power line, eliminating the direct electrical connection that causes power harvesting impacts. This intermediary structure maintains relative simplicity while dramatically improving measurement precision by isolating the measurement circuit from voltage fluctuations caused by power extraction

Inventive Principle:

Principle #24Intermediary (Mediator)

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 capacitive voltage divider system enables precise and safe measurement of high-voltage power line parameters, reducing measurement inaccuracies and ensuring continuous power supply to sensor units, facilitating improved power line management and fault detection.

Implementation Method 1

a capacitive voltage divider system with sensor units connected to power lines using capacitors, allowing for safe and accurate voltage measurement across a lower voltage range

Methodology Applied

Scientific EffectCapacitive voltage division: Capacitance

Implementation Method 2

providing power to the sensor units through the capacitive coupling, even when no current is flowing

Methodology Applied

Scientific EffectCapacitive power transfer: Capacitance

Data Source

PatentEP3186646B1Power extraction for a medium voltage sensor using a capacitive voltage divider

Publication Date: 2021.10.20 ACLARA TECHNOLOGIES LLC

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AI summary

A sensor unit coupled to a first wire of a power line for measuring power-related parameters of the power line. The sensor unit contains a first capacitor and makes voltage measurements relative to another wire, to which the sensor unit is coupled by a second capacitor. The captors form a voltage divider such that the sensor unit may measure a voltage in a range much lower than the voltage on the power line. Additionally, the capacitive voltage divider yields a voltage that can be used to power the sensor unit, including by charging an energy storage device. The sensor unit may also supply power to other nearby devices, such as other devices that form a mesh sensor network.