Single-channel safety output for cross-fault detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing safety switching devices require additional terminals and lines to achieve a high safety category, such as category 4, and are prone to cross faults due to dual-channel configurations, which increases complexity and cost.
Innovation Solution
A safety switching device system utilizing a single-channel connection with a clocked pulse signal for cross-fault detection, where the first device monitors the signal for fail-safe operation and the second device receives power from it, ensuring redundancy through dual microprocessors for high safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual-channel configuration is used to achieve high safety category, then safety reliability is improved, but device complexity and cost increase due to additional terminals and lines
Solution Approach 1:
The patent merges the functions of multiple safety channels into a single integrated channel. The single-channel safety output combines signal transmission, power supply, and fault detection capabilities that were previously distributed across multiple separate channels, thereby reducing device complexity while maintaining safety reliability through integrated monitoring of the combined signal.
2Reliability
If dual-channel configuration is used to achieve high safety category, then safety reliability is improved, but quantity of components increases due to additional terminals and lines
Solution Approach 1:
The single-channel safety output is designed to perform multiple functions simultaneously: it transmits the safety signal, provides power supply to connected devices, and enables cross-fault detection. This multi-functional approach eliminates the need for separate terminals and lines for each function, thereby reducing the quantity of components while maintaining the required safety reliability.
3Device complexity
If single-channel connection is used, then device complexity is reduced, but cross-fault detection capability is worsened
Solution Approach 1:
The patent implements feedback mechanisms within the single-channel safety output system. The control unit continuously monitors the transmitted signal and uses feedback information to detect cross-faults. This internal feedback loop enables the system to maintain cross-fault detection capability despite using a simplified single-channel connection, as the feedback provides real-time information about signal integrity and potential faults.
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a safety switching device for fail-safely switching on and off an electrical load, and to a system comprising at least two safety switching devices which interact in a fail-safe manner via a single-channel. The safety switching device comprises a fail-safe control unit; a first and a second electronic switching element; at least one input terminal for receiving a first switching signal that causes a switching of said switching elements, and a clocked output terminal (L11) for connecting said safety switching device to a second safety switching device (104). The clocked output terminal provides a clocked signal (108) depending on the first switching signal and being monitored by said control unit for performing a cross fault detection, wherein said clocked output terminal (L11) is further adapted to provide power to said second safety switching device (104), wherein said clocked signal (108) comprises a train of pulses indicative of a true safety status of the safety switching device, said clocked output terminal (L11) outputs a constant 0 V signal, if the safety status of the safety switching device indicates a fault, and wherein the clocked signal (108) differs from all other clocked signals present in the safety switching device.