Safety Relay Independently Testable Contacts
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Solution Overview
Problem
Existing safety relays in process control systems are expensive to maintain and operate due to the need for physical removal from the process to test their operation, and they cannot identify inoperable contacts without shutting down the system, which increases production costs and reduces testing frequency.
Innovation Solution
A safety relay with independently testable contacts, configured with parallel relay coils and series-connected switches, allowing for the testing of each relay contact without disrupting the system's operation, using a signal to identify operable or inoperable contacts based on measured electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If force-guided relays with mechanically linked relay contacts are used, then the safety relay provides multiple switching elements to break electrical paths, but the relay must be physically removed from the process to test operation and cannot identify inoperable contacts without system shutdown
Solution Approach 1:
The patent divides the relay testing function into independent segments by providing individual test switches (402, 404, 406) for each relay contact. This allows each contact to be tested independently while the relay remains installed in the process, eliminating the need for physical removal and enabling continuous operation during testing.
Solution Approach 2:
The patent introduces test switches as intermediary components between the operator and the relay contacts. These switches enable indirect testing of the relay contacts by routing test signals through the switches, allowing operation verification without direct physical manipulation or system shutdown.
2Reliability
If force-guided relays with mechanically linked relay contacts are used, then the relay contacts move together when relay coils are energized, but maintenance costs and operational costs increase due to required physical removal for testing
Solution Approach 1:
The patent segments the testing capability for each relay contact, allowing individual contacts to be tested and identified for potential replacement. This enables selective maintenance of only the faulty contacts rather than replacing entire relay assemblies, reducing maintenance costs and simplifying the replacement process.
Solution Approach 2:
The relay system performs self-diagnosis through the test switches and electrical characteristic measurements, automatically identifying inoperable contacts without requiring external intervention or system shutdown. This self-service capability reduces operational costs and enables proactive maintenance scheduling.
3Measurement precision
If the relay must be physically removed from the process to test operation, then testing can be performed, but system operation is disrupted and production costs increase
Solution Approach 1:
The patent enables preliminary testing of relay contacts through the test switches before actual system operation is affected. This preliminary action allows verification of contact functionality during normal operation, preventing unexpected failures and maintaining continuous productivity.
Solution Approach 2:
The patent maintains continuous useful action by allowing relay testing to occur during normal system operation. The test switches enable testing without interrupting the process, ensuring uninterrupted productivity while maintaining measurement precision for contact functionality verification.
4Reliability
If inoperable contacts cannot be identified without system shutdown, then safety is maintained, but testing frequency decreases and maintenance costs increase
Solution Approach 1:
The patent implements feedback mechanisms through electrical characteristic measurements that provide real-time information about relay contact status. This feedback allows continuous monitoring and identification of inoperable contacts during normal operation, enabling frequent testing without system shutdown and maintaining high testing frequency while ensuring safety.
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
Enables frequent and non-disruptive testing of safety relays, reducing operational impacts and maintenance costs, while ensuring continuous operation of field devices and process control systems.
Implementation Method 1
a first relay coil operatively coupled to the first relay contact and a second relay coil operatively coupled to the second relay contact
Data Source
AI summary
Methods, apparatus, and articles of manufacture related to safety relays having independently testable relay contacts are disclosed. In one disclosed example, a safety relay includes a plurality of relay coils, each of which is coupled in parallel to a first node via a respective one of a plurality of switches. The disclosed example also includes and a plurality of relay contacts, each of which corresponds to a respective one of the plurality of relay coils. The relay contacts of the safety relay are coupled in series and independently controllable by respective ones of the switches.