Integrated Knife Disconnect Isolator for Hazardous Field Devices
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Solution Overview
Problem
Existing disconnection methods for electronic field devices in process environments, such as knife-disconnect switches, are complex and require additional system elements like marshalling cabinets, which increase costs and vulnerability to errors, while not providing full isolation between field device lines.
Innovation Solution
Integrating disconnect elements directly into the functional device where field device wiring connects to process electronics, eliminating the need for a marshalling cabinet by mounting knife-disconnect switches on isolators or barriers within the isolator cabinet, thereby simplifying wiring and reducing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If knife-disconnect switches are mounted in a marshalling cabinet, then reliable disconnection and visible indication are provided, but system complexity and wiring requirements increase
Solution Approach 1:
The disconnect element is merged with the functional device (isolator or barrier) by mounting it directly on the same printed circuit board. This integration eliminates the need for a separate marshalling cabinet and reduces wiring complexity while maintaining reliable disconnection capability.
Solution Approach 2:
The functional device serves multiple functions: it provides intrinsic safety functionality (isolator or barrier) and simultaneously houses the disconnect element. This multi-functionality reduces the overall number of system components needed.
2Ease of operation
If knife-disconnect switches are mounted in a marshalling cabinet, then disconnection indication is provided, but additional system elements and costs are required
Solution Approach 1:
The disconnect element integrates the disconnection function and visual indication directly into the functional device housing. The transparent or translucent cover allows visual confirmation of disconnect status without requiring separate indication mechanisms.
3Device complexity
If disconnect elements are integrated into the functional device, then wiring complexity is reduced, but full isolation between field device lines may be compromised
Solution Approach 1:
The disconnect element physically separates and isolates individual wire connections through its blade structure. When opened, the blade creates a physical gap that ensures complete electrical isolation between live and disconnected lines, maintaining safety even with integrated mounting.
Data Source
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Figure 2A
AI summary
The invention provides for an electronic functional device such as an isolator/barrier for input/output process connection to a plurality of field devices possibly operating in a hazardous environment, the functional device having mounted there-to a disconnect element, such as a knife disconnect element, so as to be associated therewith and to provide disconnect functionality between the field devices and the isolator/barrier device, the mounting of the disconnect element at the isolator/barrier device also serving to provide further indication of the field device associated with the disconnect element.