AVTR Function Block for Independent Trip Limit Selection

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Solution Overview

Problem

Current process control systems face challenges in implementing multiple trip limits for devices, including issues with detecting key switch malfunctions, lack of time limits for abnormal operational states, non-independent trip limits, and configuration errors leading to incorrect trip limits.

Innovation Solution

A method and apparatus that allow for separate and independent configuration of multiple trip limits for a device, with internal logic within the AVTR function block to determine which trip limit to apply based on operational states and time limits, eliminating the need for manual tracking and calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual tracking and calculations are used to manage trip limits, then operators can monitor device operation, but operator workload increases and errors occur

Engineering Contradiction:

Improvetrip limit application accuracyVSAvoidoperator workload

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The AVTR function block automatically determines which trip limit to apply based on the received operational state input, eliminating the need for operators to manually track and calculate the appropriate trip limit. The function block self-manages the selection logic internally.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

An operational state input signal acts as an intermediary between the device operational conditions and the trip limit selection. This input signal enables the AVTR function block to automatically determine the correct trip limit without requiring manual operator intervention.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple independent trip limits are configured, then accurate trip limit selection is achieved, but configuration complexity increases

Engineering Contradiction:

Improvetrip limit selection accuracyVSAvoidfunction block configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The AVTR function block is enhanced to handle multiple trip limits and operational states within a single universal configuration. The same function block structure accommodates different trip limits by receiving an operational state input, rather than requiring separate function blocks for each trip limit scenario.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The trip limit configuration is segmented into independent trip limit values and an operational state input signal. This allows each trip limit to be configured independently while using a single unified function block to manage them all based on the operational state.

Inventive Principle:

Principle #1Segmentation

3Extent of automation

If key switch status is monitored to determine operational state, then trip limit selection can be automated, but undetected malfunctions may occur

Engineering Contradiction:

Improvetrip limit selection automationVSAvoidkey switch malfunction detection

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

The system uses feedback from the operational state input (such as key switch status) to automatically select the appropriate trip limit. The AVTR function block continuously monitors this input and adjusts the applied trip limit based on the current operational state, creating a closed-loop control system.

Inventive Principle:

Principle #23Feedback

4Adaptability or versatility

If trip limits are applied without time limits, then operational flexibility is maintained, but abnormal states may persist indefinitely

Engineering Contradiction:

Improveoperational state flexibilityVSAvoidabnormal state duration

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of moving object

Solution Approach 1:

The system implements periodic reassessment of the operational state through the continuous monitoring of the operational state input signal. This allows the trip limit to be reapplied or removed periodically based on whether the abnormal condition persists or has been resolved, enabling time-based control of abnormal states.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS9239576B2Methods and apparatus to apply multiple trip limits to a device in a process control system

Publication Date: 2016.01.19 FISHER ROSEMOUNT SYST INC

AI summary

Methods and apparatus to apply multiple trip limits to a device in a process control system are disclosed. An example method involves monitoring a value of a parameter associated with the operation of the device and receiving an input indicative of an operational state of the device, where a first input indicates a first operational state and a second input indicates a second operational state. If the first input is received, comparing via a function block the value of the parameter to a first trip limit, and if the second input is received, comparing via the function block the value of the parameter to a second trip limit, and implementing a response based on the comparison.