Dual-Mode Conductive Capacitive Level Probe

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Solution Overview

Problem

Conductive level detection methods fail to reliably monitor media with low electrical conductivity, such as distilled water or oils, as the change in conductivity is too small to be accurately recorded, and existing solutions require complex adjustments for changing media properties.

Innovation Solution

A device and method that alternately operate in conductive and capacitive modes, using measured values from both modes to determine media-specific properties like electrical conductivity and dielectric constant, allowing for reliable monitoring across a broader range of media conductivities, with a control/evaluation unit generating messages or switching signals based on tolerance bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive level detection method is used, then monitoring of conductive media is reliable, but monitoring of non-conductive or low-conductivity media fails

Engineering Contradiction:
Improvereliability of level monitoringVSAvoidapplicability to different media conductivity ranges
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The measuring device dynamically switches between conductive and capacitive operating modes based on the detected conductivity of the medium. The control/evaluation unit alternates between the two modes and selects the appropriate measurement results, making the system adaptive to different media properties rather than being fixed in one mode.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The measuring probe is designed to perform both conductive and capacitive measurement functions using the same physical probe structure. This multi-functionality allows a single device to reliably monitor both conductive and non-conductive media, eliminating the need for separate specialized probes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If complex adjustment processes are implemented to adapt to changing media, then measurement accuracy improves, but device complexity increases

Engineering Contradiction:
Improveaccuracy of medium property monitoringVSAvoidcomplexity of adjustment processes
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system automatically determines which operating mode (conductive or capacitive) is appropriate based on the medium's properties and seamlessly switches between modes without requiring manual intervention. The control/evaluation unit handles the adaptation autonomously, eliminating complex adjustment processes while maintaining measurement accuracy.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system changes its measurement parameters by switching between conductive and capacitive modes depending on the medium's conductivity. This parameter adaptation allows accurate measurement across different media types without requiring physical adjustments or complex calibration procedures.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If alternating conductive and capacitive modes are used, then monitoring range is extended, but device complexity increases

Engineering Contradiction:
Improverange of media conductivity coverageVSAvoidcomplexity of dual-mode operation
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines both conductive and capacitive measurement capabilities into a single integrated measuring probe and control system. By merging these two measurement principles into one device with unified control logic, the system achieves extended monitoring range without proportionally increasing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables reliable monitoring of media-specific properties and process control across an extended range of conductivities, including non-conductive and high-conductive media, by combining the advantages of conductive and capacitive methods, and allows for adaptive switching curve adjustments to specific process conditions.

Implementation Method 1

the measuring probe (1) is operated in a conductive operating mode (II) as a conductive measuring probe (1)

Methodology Applied
Scientific EffectElectrical Conductivity: Conduction (electrical)

Implementation Method 2

operated in a capacitive operating mode (I) as a capacitive measuring probe (1)

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP2994725B1Method and apparatus for monitoring of at least one specific property of a fluid medium for a level measurement
Publication Date: 2020.01.15 ENDRESS & HAUSER GMBH & CO KG
  • EP2994725B1 patent drawingFigure 1~2b
  • EP2994725B1 patent drawingFigure 3~4
  • EP2994725B1 patent drawingFigure 5

AI summary

The invention relates to a method and a device for monitoring at least one medium-specific property of a medium in automation technology by means of a measuring probe (1), wherein the at least one medium-specific property is determined in a conductive operating mode and in a capacitive operating mode of the measuring probe (1), wherein the conductive operating mode and the capacitive operating mode are activated in alternation, wherein the measured values that are determined in at least one of the two operating modes are used to check if the at least one medium-specific property to be monitored lies within a specified tolerance band, and wherein an indication and/or a switching signal is generated if the at least one medium-specific property to be monitored lies outside the specified tolerance band.