Valve Diagnostic Power Selection Using Limit Switch Outputs
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Solution Overview
Problem
Industrial transmitters and mechanical limit switches in control valve systems lack the ability to collect diagnostic information, leading to premature replacement of valves due to uniform maintenance schedules, which increases costs and does not account for varying usage rates among valves.
Innovation Solution
A diagnostic module that selectively switches between available power sources, including a 4-20 mA signal and limit switch outputs, to operate without an external power source, enabling the collection of diagnostic data on valve usage and wear, thereby identifying valves requiring maintenance based on actual usage rather than schedules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform maintenance schedules are used for all valves, then maintenance can be systematically performed, but valves are replaced prematurely increasing costs without accounting for varying usage rates
Solution Approach 1:
The system changes the maintenance parameter from time-based (uniform schedules) to usage-based (actual valve operation cycles). The diagnostic module monitors valve usage parameters such as actuation count, position changes, and operational duration to dynamically adjust maintenance timing, replacing valves based on actual wear rather than predetermined intervals.
Solution Approach 2:
The diagnostic module continuously collects feedback data on valve usage and wear conditions through sensors monitoring position, actuation frequency, and operational parameters. This feedback loop enables real-time assessment of valve health and predictive maintenance scheduling, preventing both premature replacement and failure.
2Loss of information
If diagnostic modules are added to collect usage data, then maintenance can be optimized based on actual usage, but device complexity increases requiring additional power sources
Solution Approach 1:
The diagnostic module is designed to operate using existing power sources already present in the control valve system, such as the 4-20 mA control signal or limit switch power. By leveraging multi-functionality of existing components to provide both control and diagnostic power needs, the system avoids adding dedicated power sources and maintains simplicity.
Solution Approach 2:
The diagnostic module harvests power from the valve's own control circuitry and operational signals rather than requiring external power infrastructure. The 4-20 mA control signal and limit switch outputs serve dual purposes: maintaining valve control and powering diagnostic functions, enabling the system to self-power its monitoring capabilities.
3Device complexity
If existing power sources are used to power the diagnostic module, then no external power source is needed reducing complexity, but power availability from existing sources must be sufficient
Solution Approach 1:
The power selection circuit dynamically switches between multiple power sources based on availability and suitability for different operational modes. During normal operation, the module draws power from the 4-20 mA control signal; during diagnostic tasks requiring higher power, it switches to limit switch power or alternative sources, ensuring continuous reliable operation without external power infrastructure.
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture are disclosed for power selection. An example method includes, when a first limit switch detects that a first device is in a first position, powering a second device based on a first output of the first limit switch, when a second limit switch detects that the first device is in a second position, powering the second device based on a second output of the second limit switch, and performing the diagnostic task based on at least one of the first output or the second output.