Electromagnetic Flow Meter Fault Detection via Voltage Summation
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Solution Overview
Problem
Conventional tri-state magnetic excitation electromagnetic flow meters have low reliability in fault evaluation due to the detection of differential noise as a small value, which limits the accuracy of fault detection.
Innovation Solution
An electromagnetic flow meter that calculates the sum of voltages between electrodes during specific non-magnetic-excitation periods to detect differential noise as a large value, incorporating a between-electrodes voltage sum calculating means and fault evaluating means to enhance fault detection reliability, and uses band-pass filters, an adding circuit, and a frequency component extracting filter to isolate specific frequency components and exclude background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage difference calculation method is used between electrodes, then the measurement system remains simple, but the fault detection reliability is low due to differential noise being detected as a small value
Solution Approach 1:
The voltage detection process is segmented into two separate voltage measurements (Va and Vb) taken at different time points during the non-magnetic excitation periods, rather than directly measuring the voltage difference. This segmentation allows each voltage to be measured and processed independently, improving fault detection capability while managing circuit complexity through temporal separation of measurements.
Solution Approach 2:
The system performs preliminary voltage measurements during non-magnetic excitation periods before actual flow measurement. By measuring voltages Va and Vb during these idle periods and calculating their sum, the system prepares fault detection data in advance, enabling reliable fault detection without interfering with the main flow measurement function.
2Measurement precision
If voltage measurements are taken during non-magnetic excitation periods, then differential noise can be detected, but background noise and interference signals are also present
Solution Approach 1:
The system utilizes the periodic non-magnetic excitation periods to perform voltage measurements. By scheduling measurements during these regular intervals when the magnetic excitation coil is not active, the system captures differential noise characteristics periodically, enabling consistent fault detection while avoiding continuous measurement interference.
Solution Approach 2:
The system calculates the sum of voltages Va and Vb and uses this feedback signal for fault detection. The feedback mechanism compares the measured voltage sum against expected ranges to identify faults such as empty tubes or electrode adhesions, continuously monitoring system health based on the periodic measurements.
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 solution significantly increases the reliability of fault detection by summing voltages across electrodes, amplifying differential noise, and filtering out background noise, enabling timely detection of faults such as empty tubes or electrode adhesions with improved accuracy.
Implementation Method 1
2 is a magnetic excitation coil that is disposed with the direction in which the magnetic field is generated being perpendicular to the direction of flow of the fluid
Implementation Method 2
a signal electromotive force that is produced between a pair of electrodes that are disposed facing each other within a measuring tube
Data Source
AI summary
With the non-magnetic-excitation period until a specific amount of time elapses from the commencement of the transition from the positive magnetic excitation period to the non-magnetic-excitation period defined as a first period T1 and the non-magnetic-excitation period until a specific amount of time elapses from the commencement of the transition from the negative magnetic excitation period to the non-magnetic-excitation period defined as a second period T2, the sum of a voltage produced at a detecting electrode and a voltage produced at a detecting electrode, at the time of each first period T1 and second period T2, is calculated as a sum of voltages between electrodes, and a fault in an electromagnetic flow meter, such as detection of an empty state, adhesion of an electrically insulating object to an electrode, and so forth, is evaluated based on the sum of voltages between electrodes.