Control Valve Positioner Redundancy for Automatic Failover
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Solution Overview
Problem
Process control systems face disruptions when field devices, such as control valves, fail due to severe operating environments or extended maintenance cycles, leading to reduced availability and performance.
Innovation Solution
A high-availability configuration using a pair of positioners, where one acts as a primary and the other as a backup, with a switch that monitors the operational state of the primary positioner and automatically enables the secondary positioner's output if the primary fails, ensuring continuous operation of the control valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single positioner is used to control a valve, then the device complexity is low, but the reliability decreases when the positioner fails in severe operating environments
Solution Approach 1:
The system divides the positioner function into two separate positioners (first and second positioners) that independently control the same valve. This segmentation allows one positioner to serve as a backup for the other, improving reliability while maintaining manageable complexity through functional division
Solution Approach 2:
The system pre-configures a second positioner as a backup before any failure occurs. The switch is pre-programmed to automatically detect positioner failures and redirect control signals to the standby positioner, ensuring immediate failover without manual intervention or system reconfiguration
2Reliability
If a redundant positioner system is implemented, then the reliability improves, but the device complexity increases
Solution Approach 1:
A switch component acts as an intermediary between the two positioners and the valve actuator. This intermediary automatically routes control signals from either positioner to the actuator based on operational status, simplifying the overall system architecture while enabling redundancy without requiring complex control logic or additional hardware
Data Source
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AI summary
A system and method for controlling a valve increases the availability of a control valve assembly used in a control process. A pair of positioners (204,206) are arranged in a high-availability configuration and individually coupled to a controller (216). A first positioner (204) includes an output coupled to a switch (218) and a second positioner (206) includes an output coupled to the switch (218). The operating state of the first positioner (204) is monitored and the output of the first or second positioner (204,206) allowed to pass through the switch (218) to the control valve (214) is dependent upon the operating status of the first positioner (204).