Inductive Conductivity Sensor Failure Detection Circuit
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Solution Overview
Problem
Existing methods for detecting failures in electromagnetic conductivity measurement devices, such as open-circuit and short-circuit failures, can lead to incorrect conductivity readings, and existing solutions complicate the device with additional components like extra loops, increasing cost and complexity.
Innovation Solution
A simple detection method and circuit that applies an additional direct current signal to the measurement device's coils to generate a derived signal, which is measured against threshold values to determine failure conditions, avoiding the need for additional components and maintaining measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional wire loop is introduced into the measurement sensor to form a conductive loop through the excitation coil and the induction coil, then open-circuit failure detection is enabled, but the device becomes more complicated
Solution Approach 1:
The invention extracts the failure detection function from the main measurement circuit by applying a separate direct current signal through a high-value resistor to the coil. This allows open-circuit failure detection without requiring additional wire loops or modifying the sensor structure, thereby maintaining simplicity while enabling reliability monitoring.
2Reliability
If existing failure detection methods are used, then open-circuit and short-circuit failures can be detected, but incorrect conductivity readings may still occur
Solution Approach 1:
The invention performs preliminary failure detection by monitoring the voltage across the coil before conducting conductivity measurements. By applying a direct current signal and measuring the resulting voltage, the system can identify open-circuit or short-circuit conditions in advance, preventing incorrect conductivity readings from being recorded.
3Reliability
If additional components are added to the measurement device for failure detection, then reliability is improved, but cost and complexity increase
Solution Approach 1:
The invention makes the existing coil serve multiple functions: it acts as both the measurement sensor for conductivity detection and the test object for failure detection. By applying a direct current signal through a high-value resistor and monitoring the voltage, the same coil structure is used for both measurement and reliability monitoring, eliminating the need for separate detection components.
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 approach provides a reliable and cost-effective means to detect open-circuit and short-circuit failures, ensuring accurate conductivity measurements without complicating the device, thus enhancing measurement reliability.
Implementation Method 1
A non-contact type measurement applies the principle of electromagnetic induction and is therefore also referred to as an electromagnetic conductivity measuring method or an inductive conductivity measuring method
Data Source
Figure 1~3
AI summary
The present invention discloses a method and device for detecting open-circuit and short-circuit failure in an electromagnetic (inductive) measurement of the conductivity of liquids. An electromagnetic measurement of the conductivity of a liquid is performed by immersing a sensor into the liquid, wherein the sensor includes at least 2 toroidal cores, one of them carrying an excitation coil and the other carrying an induction coil. When an AC excitation voltage is applied to the excitation coil, an induced current or voltage can be measured in the induction coil which is proportional to the conductivity of the measured liquid. The present invention discloses a method and device for detecting open-circuit and short-circuit failure on the sensor and cable wiring. Its concept is to add a very small DC current at the terminal of the excitation coil or induction coil in order to detect an open-circuit failure of the device, and to monitor the output swing of the excitation-driving circuit in order to detect a short-circuit failure of the device. The purpose is to improve the reliability of the measurement result.