Redundant Analog Input Assembly Without Voltage Division Error
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Solution Overview
Problem
Existing redundant analog input units for measurement current require arithmetic correction of measurement values due to voltage division caused by resistance ratios between high-ohmic and current-measuring resistors, limiting precision and accuracy.
Innovation Solution
Each analog input unit has its high-ohmic voltage-measuring entry point directly connected to the analog entry point, allowing comparison of digital measurement values with a threshold, and switching between high-ohmic and low-ohmic states to ensure all units measure the same voltage, eliminating voltage division and enabling higher resistance ratios without accuracy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the controllable switch is closed in both input units to enable analog input operation, then the measurement current can be measured, but the measurement current is divided into halves over the two low-ohmic current-measuring resistors, requiring arithmetic correction and limiting precision
Solution Approach 1:
The patent extracts the voltage division problem by taking out one of the high-ohmic resistors from the measurement path. When the controllable switch is closed, the high-ohmic resistor is excluded from the circuit, preventing voltage division and eliminating the need for arithmetic correction, thus improving measurement precision while maintaining analog input operation
Solution Approach 2:
The patent applies dynamics by making the circuit configuration changeable through the controllable switch. The switch dynamically changes the circuit state between measuring analog input current (switch closed, high-ohmic resistor disabled) and binary input (switch open, voltage division active), allowing the system to adapt its measurement mode based on requirements
2Productivity
If a high resistance ratio between current-measuring resistor and high-ohmic resistor is used to achieve desired current distribution, then the current distribution ratio can be adjusted, but the precision is limited by unavoidable and unknown line resistances
Solution Approach 1:
The patent removes the high-ohmic resistor from the measurement path when analog input is required, eliminating the voltage division effect entirely. This extraction approach allows for higher resistance ratios without being affected by line resistances, as the high-ohmic resistor no longer participates in the measurement circuit
Solution Approach 2:
The controllable switch acts as an intermediary that controls the inclusion or exclusion of the high-ohmic resistor in the measurement circuit. By switching the resistor out of the path, the system achieves precise current measurement without the interfering effect of line resistances on voltage division
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration eliminates the need for arithmetic correction, significantly increases the resistance ratio, and ensures accurate measurement by self-monitoring and automatic error detection, enhancing operational safety and precision.
Implementation Method 1
a current-measuring resistor (15, 24) for converting a measurement current (I) into a voltage drop
Implementation Method 2
a voltage-measuring device (8, 19) with a high-ohmic voltage-measuring entry point (11, 20), for converting a voltage that is applied to the voltage-measuring entry point into a digital measurement value
Data Source
AI summary
At least two redundant analog input units for a measurement current have analog inputs which are connected in parallel and upon which voltage measuring devices directly lie to convert respectively applied voltages into a digital measurement value, wherein in order to detect errors, in particular in order to detect wire breakage, each analog input unit compares its generated measurement value with a threshold and outputs an error message if a measurement value is detected that falls below the threshold, where if the analog input of the analog input unit is in the low-resistance state, then the at least one other analog input unit is additionally caused to assume a current-measuring function and switch the analog input of the analog input unit to a low-resistance state.