Redundant Input Module Filter Diagnostics for Constant Signal Faults
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Solution Overview
Problem
Detecting failures in redundant signal paths within industrial control systems is challenging, especially when the input signal remains constant, as existing methods rely on signal changes to identify faulty components, potentially leading to undetected failures in electronic components along the signal path.
Innovation Solution
A safety-rated input module with redundant signal paths that injects a test signal at a predefined frequency to determine the frequency response of each path, allowing for the identification of failures by comparing the responses, thereby pinpointing the specific location of faults within the filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing fault detection methods relying on signal changes are used, then the system can detect faults when signals vary, but failures in electronic components along the signal path remain undetected when the input signal remains constant
Solution Approach 1:
The system performs preliminary diagnostic actions by injecting test signals at predefined frequencies to evaluate the frequency response of electronic components before actual operation. This allows the system to proactively identify failed components in redundant signal paths even when the normal input signal remains constant, resolving the contradiction between maintaining reliability and overcoming detection difficulty.
Solution Approach 2:
The system introduces an intermediary test signal as a mediator to evaluate the health of electronic components. This test signal, injected at predefined frequencies, serves as a diagnostic tool that interacts with the electronic components to reveal their operational status without relying on the normal input signal, thus enabling detection of failed components that would otherwise remain undetected.
2Reliability
If redundant signal paths are implemented to detect failures, then the system can identify differences between paths, but the specific location of faults within the filter cannot be pinpointed
Solution Approach 1:
The system segments the fault detection process by evaluating different frequency responses of electronic components within the redundant signal paths. By analyzing the frequency response at predefined frequencies, the system can identify which specific component or stage in the filter path is faulty, rather than merely detecting that a fault exists somewhere in the path. This segmentation of the diagnostic approach preserves fault location information.
Solution Approach 2:
The system changes the parameter being measured by evaluating the frequency response at multiple predefined frequencies. This parameter change approach allows the system to characterize the behavior of different electronic components along the signal path, enabling identification of the specific fault location based on which component's frequency response deviates from expected values.
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 method enables the detection of failed electronic components in redundant signal paths without relying on input signal changes, ensuring timely identification and maintenance, thereby enhancing the reliability and safety of industrial control systems.
Implementation Method 1
generate a test signal at a predefined frequency and determine a frequency response of each filter as a function of the test signal
Data Source
AI summary
A system and method for detecting a failure in a redundant signal path during operation of the redundant path is disclosed. A test signal is sequentially injected into each signal path while an input signal is conducted by the other signal path not receiving the test signal. The test signal is selected at a frequency to verify operation of a filter connected in series along each path. A processor generates the test signal, injects the test signal at the input of the filter, and receives the output of the filter. The processor then generates a frequency response of the filter in each signal path as a function of the output from the filter and of the original test signal. The frequency response obtained along each of the redundant signal paths is compared to each other to detect a failure of one of the filters present along the respective signal paths.