Galvanically Isolated Analog Input Switching for Ground Loop-Free Acquisition
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Solution Overview
Problem
Conventional multi-channel measurement data acquisition devices are prone to ground loops and impedance coupling, which degrade measurement quality and require complex galvanic decoupling of sensors, leading to equipment complexity and reduced accuracy.
Innovation Solution
The device features a galvanically decoupled analog input module with a controllable electronic analog signal switch and analog-to-digital converter, ensuring potential-free operation and high dielectric strength between channels, eliminating ground loops and impedance coupling, while allowing flexible configuration of connection terminals to optimize device size and functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic decoupling is implemented for all sensors to protect against ground loops, then protection against ground loops is improved, but equipment complexity increases
Solution Approach 1:
The device is segmented into multiple galvanically isolated modules (analog input module, analog-to-digital converter, digital processing unit), each operating at different potential levels. This segmentation allows protection against ground loops without requiring all sensors to be galvanically decoupled, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
A potential-free electronic analog signal switch device acts as an intermediary between sensors at different potentials and the analog-to-digital converter. This intermediary component enables safe signal transmission across potential differences without requiring direct galvanic decoupling of all sensors, thus protecting against ground loops while simplifying equipment configuration.
2Object-affected harmful factors
If differential input mode is used to reduce ground loop risks, then electromagnetic interference compensation is improved, but protection against impedance coupling from ground loops remains insufficient
Solution Approach 1:
The potential-free electronic analog signal switch device serves as an intermediary that breaks the ground loop path, providing protection against impedance coupling that differential input mode alone cannot achieve. This intermediary component allows the system to use simpler single-ended input mode while still protecting against ground loop effects.
3Reliability
If all sensors are galvanically decoupled to eliminate ground loops, then ground loop protection is improved, but measurement accuracy may be reduced
Solution Approach 1:
Galvanic isolation is selectively applied only where necessary (at the analog-to-digital converter interface) rather than to all sensors. This segmented approach provides ground loop protection while maintaining signal integrity for measurements, avoiding the accuracy degradation that would result from universal galvanic decoupling.
Solution Approach 2:
The system automatically adapts to the potential level of each connected sensor through the potential-free electronic analog signal switch, eliminating the need for manual configuration or complex decoupling circuits. This self-adjusting capability provides ground loop protection while preserving measurement accuracy without requiring user intervention.
4Adaptability or versatility
If the analog input module assumes ground reference of switched-through signals, then adaptation to analog signals is improved, but potential differences between channels increase
Solution Approach 1:
The electronic analog signal switch device with high dielectric strength acts as an intermediary that can withstand significant potential differences between channels. This intermediary component enables the analog input module to adapt to different signal ground references while the high dielectric strength provides the necessary insulation to handle increased potential differences safely.
Data Source
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AI summary
The apparatus (1) has an analog input assembly (10) including analog inputs, and a controllable electronic analog signal switch device (12). Control lines of the electronic analog signal switch device of an analog-digital converter (14) of the assembly, and an output of the analog-digital converter are respectively galvanically decoupled from a ground such that the analog input assembly acquires the switched-through analog signal after an analog signal is switched to the analog-digital converter. An independent claim is also included for a method for operating a multi-channel measurement data acquisition apparatus.