Switch-Off Acceleration Circuit for Fault-Monitored Load Shutdown
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Solution Overview
Problem
Safety-related automation systems face challenges in efficiently switching off loads while maintaining error detection capabilities in supply lines, leading to prolonged switch-off processes and increased power loss.
Innovation Solution
A switch-off acceleration device is connected between input/output devices and loads without signal decoupling, providing electrical resistance based on voltage during the switch-off process to accelerate capacitive discharge, ensuring quick and low-loss shutdowns while detecting faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a switch-off acceleration device is connected between the input/output device and the load, then the switch-off process is accelerated and power loss is reduced, but fault detection in the supply line may be impaired
Solution Approach 1:
The switch-off acceleration device is connected to the supply line through a coupling capacitor that acts as an intermediary. This capacitor blocks DC fault signals from being affected by the acceleration device while allowing the acceleration function to operate. The coupling capacitor thus mediates between the need for accelerated switch-off and the need to preserve fault detection capability.
2Reliability
If signal decoupling is used to preserve fault detection, then fault detection is maintained, but the switch-off process cannot be accelerated
Solution Approach 1:
The coupling capacitor serves as an intermediary that enables both functions simultaneously. It allows the switch-off acceleration device to operate while blocking DC signals, thus maintaining fault detection capability without sacrificing switch-off acceleration.
Solution Approach 2:
The system changes the electrical parameters of the supply line dynamically by introducing the coupling capacitor during switch-off operations. This parameter change allows the line to exhibit capacitive coupling characteristics during normal operation (preserving fault detection) while enabling accelerated discharge during switch-off.
3Loss of time
If the switch-off process is accelerated, then the switch-off time is reduced, but power loss increases
Solution Approach 1:
The switch-off acceleration device operates periodically or transiently only during the switch-off phase rather than continuously. The coupling capacitor charges during normal operation and then discharges during switch-off, creating a periodic action pattern that achieves acceleration only when needed, minimizing overall power loss.
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
The solution enables rapid and low-power switch-off processes with preserved error detection capabilities, shortening the switch-off duration and time for recognizing proper shutdowns.
Implementation Method 1
a shutdown acceleration device which is configured to provide an electrical resistance between the load and ground connections, depending on the voltage applied to the load connection during a shutdown process, so that an accelerated discharge of capacitive elements occurs
Data Source
Figure 1
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Figure 4
AI summary
The system (10) has an input and/or output device (20) comprising load terminals (32,36), a ground terminal (34) and a monitoring device for monitoring the voltage drop at load terminals during turn-off operation. A shut-accelerating device (80) connected to load terminal and optionally to ground connection load (100), has electric resistor between the load and ground terminals so that accelerated discharge of capacitive element (90) is performed as a function of applied load at the turn-off during power supply voltage. A supply voltage source (40) feeds the load.