Two-Channel Switching Assembly Monitoring via Pulsed Diagnostics
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Solution Overview
Problem
Current methods for increasing diagnostic coverage in functional safety, particularly in electrical receiving elements, do not effectively utilize internal circuit parts for enhanced monitoring, leading to a gap in achieving higher safety integrity levels.
Innovation Solution
An electrical switching arrangement with two channels, where internal safety signals are generated to control voltage interrupters, and a pulsed diagnostic signal is superimposed on these signals to alternately interrupt supply variables, allowing for internal monitoring and measurement to detect deviations and malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diagnostic coverage is increased by adding more monitoring functions, then safety integrity level is improved, but device complexity increases
Solution Approach 1:
The switching arrangement performs self-diagnosis by using its own internal circuit parts (voltage interrupters, channels) to monitor itself. The pulsed diagnostic signal traverses through the internal channels and is evaluated by the control unit, enabling the system to detect its own malfunctions without external testing equipment or additional monitoring hardware.
Solution Approach 2:
The internal circuit parts of the switching arrangement serve dual functions: they perform their primary switching and power interruption functions while simultaneously serving as test paths for diagnostic monitoring. The voltage interrupters and channels are used both for safety function execution and for carrying the pulsed diagnostic signal through the system.
2Reliability
If redundant components are added to improve diagnostic coverage, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The switching arrangement performs self-diagnosis by using its own internal circuit parts (voltage interrupters, channels) to monitor itself. The pulsed diagnostic signal traverses through the internal channels and is evaluated by the control unit, enabling the system to detect its own malfunctions without external testing equipment or additional monitoring hardware.
3Reliability
If internal monitoring is implemented using existing circuit parts, then diagnostic coverage is improved, but the risk of interference with safety signals increases
Solution Approach 1:
The diagnostic signal is applied in pulsed form rather than continuously. The control unit generates pulsed diagnostic signals that are superimposed on the safety signals, allowing the diagnostic function to activate periodically without continuously interfering with the safety signal transmission. This periodic activation minimizes potential interference while still achieving effective diagnostic coverage.
Solution Approach 2:
The diagnostic signal is superimposed on the safety signals before they are transmitted through the channels. By preparing the diagnostic signal in advance and combining it with the safety signals at the input stage, the system ensures that the diagnostic function is integrated without disrupting the primary safety function operation.
Data Source
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AI summary
In order to specify a method for monitoring an electrical switching arrangement (100) with at least two channels (K1, K2), which is improved compared to the prior art, and which electrically connects an electrical source (Vcc) supplying the respective channel (K1, K2) to an output (A1, A2) of the respective channel (K1, K2) by forming an electrical supply quantity (V1, V2), the switching arrangement (100) is supplied with, in addition to an external safety signal (sext), from which an internal safety signal (sint,1, sint,2) is generated for each of the at least two channels (K1, K2) in order to control a voltage interrupter (S1, S2) connected in series in the respective channel (K1, K2), a pulsed diagnostic signal (d) is supplied, which is superimposed on the internal safety signals (sint,1, sint,2) in order to monitor the voltage in the respective channels (K1, K2).to alternately open and close the switched voltage interrupter (K2) and thus alternately interrupt the supply quantities (V1, V2) that are established in the respective channels (K1, K2).