Capacitive Voltage Indicator Harvesting Electric Field Energy

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Solution Overview

Problem

Existing indicator systems for power buses are limited in their ability to visually indicate an energized state without current flow, particularly at medium voltage levels, and are costly due to the use of electret devices.

Innovation Solution

The use of two electrodes that capacitively couple to energized electrical conductors to harvest an electric field, powering a rectifier and an illuminated or non-illuminated indicator, which provides a visual indication of the energized state without the need for current flow or a battery, thus reducing costs and improving performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electret devices are used to indicate energized state, then visual indication is achieved, but system cost increases

Engineering Contradiction:

Improvevisual indication reliabilityVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive electret devices with inexpensive LED indicators and simple capacitive sensing circuitry. The LED-based solution uses readily available, low-cost components that achieve the same visual indication function without the high cost associated with electret devices.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the mechanical/electrostatic electret device with an electronic circuit-based solution using capacitive sensing and LED indication. This replacement leverages electrical field detection through capacitive coupling rather than relying on electret material properties, resulting in lower cost and improved manufacturability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Use of energy by moving object

If current flow is required to power indicator, then indicator can be powered, but indication fails when no current flows

Engineering Contradiction:

Improveindicator power supplyVSAvoidindication coverage

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent enables the indicator system to power itself by harvesting energy from the electric field of the energized conductor through capacitive coupling. The circuit draws minimal power directly from the conductor's electric field, allowing the LED indicator to operate without external power sources or batteries, and crucially, without requiring current flow through the conductor.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent uses the periodic oscillation of AC power (50/60 Hz) to generate pulsing electric fields that can be rectified and stored in capacitors to provide continuous power to the LED indicator. This allows the indicator to remain powered during the entire AC cycle even when average current flow is minimal or zero.

Inventive Principle:

Principle #19Periodic action

3Power

If medium voltage levels are used, then power bus operation is achieved, but indicator operation becomes limited

Engineering Contradiction:

Improvepower bus voltageVSAvoidindicator applicability

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The patent designs the capacitive sensing circuit and LED driver to operate across a wide range of voltage levels by adjusting component values such as capacitor sizes and resistor values. The circuit can be adapted to different medium voltage levels (e.g., 2.4kV, 4.8kV, 12kV) by scaling the capacitive coupling elements and power management components, making the indicator universally applicable to various power bus voltages.

Inventive Principle:

Principle #35Parameter changes

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

This solution allows for a cost-effective and reliable visual indication of an energized power bus, even when no current is flowing, enhancing safety and reducing system costs by eliminating the need for expensive electret devices.

Implementation Method 1

two electrodes structured to capacitively couple to two energized electrical conductors, respectively, in order to harvest an electric field

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

harvest an electric field

Methodology Applied

Scientific EffectElectric field harvesting: Electric Field

Data Source

PatentUS9651587B2Apparatus including electrodes, a rectifier or circuit, and an illuminated or non-illuminated indicator for visual indication of energized electrical conductors

Publication Date: 2017.05.16 EATON INTELLIGENT POWER LTD

AI summary

An apparatus is for visual indication of an energized state of electrical conductors. The apparatus includes two electrodes structured to capacitively couple to two energized electrical conductors, respectively, in order to harvest an electric field. A rectifier is powered from one or both of the two electrodes. An illuminated indicator or a non-illuminated indicator is powered from the rectifier.