Dual-Technology Safety System for Industrial Plants
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Solution Overview
Problem
Existing safety systems for industrial installations, particularly nuclear installations, are vulnerable to common mode failures that affect both separate processing chains using redundant technologies of the same nature, lacking protection against simultaneous hardware and/or software module failures.
Innovation Solution
A compact, low-complexity system with partial redundancy using two distinct processing chains, one implementing a relay or analog circuit and the other a programmable industrial automaton, along with a test module to compare responses to test signals, ensuring protection against common mode faults through technological diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant systems with two programmable automatons are used to improve safety, then availability of safety-critical functions is improved, but vulnerability to common mode failures increases
Solution Approach 1:
The patent changes the fundamental parameter of technological homogeneity to heterogeneity by using two different technologies (relay-based and programmable automaton) for the processing chains. This diversification of technological parameters prevents common mode failures while maintaining redundancy for safety-critical functions.
Solution Approach 2:
The system combines two distinct technological approaches (relay circuitry and programmable automaton) into a composite safety system. This composite architecture leverages the strengths of both technologies while mitigating their individual weaknesses, particularly regarding common mode failures.
2Reliability
If two programmable industrial logic controllers are used for full redundancy, then safety is improved, but system complexity and cost increase
Solution Approach 1:
The patent segments the safety system into two distinct processing chains with different technological bases (relay-based and programmable). This segmentation allows each chain to be simpler in its own right while collectively providing robust safety coverage, avoiding the complexity of dual programmable controllers.
Solution Approach 2:
Instead of copying the same programmable controller twice, the patent creates a functional copy using a different technology (relay-based system). This approach maintains the redundancy principle while reducing complexity associated with duplicating complex programmable systems.
3Ease of manufacture
If homogeneous redundant technologies are used, then ease of manufacture is improved, but protection against common mode faults is lost
Solution Approach 1:
The patent deliberately changes the technological parameter from homogeneous to heterogeneous by employing relay-based and programmable automaton technologies. This parameter change sacrifices some manufacturing uniformity but gains crucial protection against common mode faults.
Data Source
Figure 1
AI summary
The invention relates to an automated safety system for an industrial installation comprising a plurality of sensors for taking measurements of an industrial process, a plurality of actuators for performing operations that depend on measurement signals delivered by said sensors, at least one first processing chain, and at least one second processing chain connecting the sensors and actuators. This system is characterized in that the first processing chain comprises at least one first processing unit implementing a first technology, while the second processing chain comprises at least one second processing unit implementing a second technology different from the first technology, so as to ensure partial redundancy of at least one critical safety function of the industrial installation.