Switchgear Actuation Sequence for Contact Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric switchgear in power distribution installations faces issues with contact deterioration and risk of welding due to thermal and electrodynamic stresses during fault conditions, and the current actuating elements have a bounce effect that increases the risk of restrike, while also requiring larger enclosures and higher costs due to the need for multiple coupling devices for each phase.
Innovation Solution
The electric switchgear configuration actuates the switch before the disconnector in breaking operations and the disconnector before the switch in connection operations, using a single actuating element for all phases, which reduces wear on the switch and prevents bounce effects, and incorporates an elastic element to minimize oscillation and a common coupling device for all phases to reduce enclosure size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switch acts before the disconnector in breaking operations, then the switch contacts are protected from thermal and electrodynamic stresses, but the disconnector must be designed to handle the sectioning function effectively
Solution Approach 1:
The operating means are divided into distinct functional components: a switch for breaking operations and a disconnector for sectioning operations. This segmentation allows each component to be optimized for its specific function, with the switch handling fault current interruption and the disconnector providing visible isolation, thereby protecting switch contacts from excessive thermal and electrodynamic stresses while maintaining system reliability.
Solution Approach 2:
The switch performs the breaking operation before the disconnector performs the sectioning operation. This preliminary action by the switch removes the fault current and load before the disconnector opens, ensuring that the disconnector operates under lighter conditions and the switch contacts are not exposed to prolonged thermal and electrodynamic stresses that would occur if the disconnector opened first under load.
2Ease of operation
If multiple coupling devices are used for each phase, then each operating means can be actuated independently, but the enclosure size and cost increase
Solution Approach 1:
Multiple coupling devices for different phases are merged into a single common coupling device that can actuate all operating means (switch and disconnector) across all phases. This unified coupling mechanism reduces the number of separate actuating components, thereby reducing the overall enclosure size and cost while still enabling independent actuation of each operating means through the shared coupling mechanism.
Solution Approach 2:
The coupling device is designed with multi-functionality to serve all phases and both the switch and disconnector operations. This universal coupling mechanism can be actuated to simultaneously or independently operate multiple circuit breakers and disconnectors across different phases, eliminating the need for separate dedicated coupling devices for each phase and reducing the overall system complexity and enclosure requirements.
3Device complexity
If a single actuating element is used for all phases, then the device complexity is reduced, but the coordination of breaking and sectioning operations becomes more challenging
Solution Approach 1:
Multiple actuating elements for different phases are merged into a single actuating element that controls all operating means across all phases. This unified actuating mechanism simplifies the device complexity by reducing the number of separate components while incorporating internal coordination mechanisms that ensure the correct sequence of operations (switch breaking before disconnector sectioning) is maintained across all phases simultaneously or in a coordinated manner.
Solution Approach 2:
The single actuating element incorporates feedback mechanisms that monitor the status of each phase and operating means, automatically coordinating the breaking and sectioning operations to ensure the correct sequence is maintained. The feedback system detects when the switch has broken the fault current and then triggers the disconnector to perform the sectioning operation, ensuring proper coordination without requiring complex manual control while still using a single actuating element.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The switchgear comprises operating means which allow performing the breaking and/or connection and/or sectioning and/or grounding operation functions of the electric circuit. The operating means comprise a vacuum switch (1 a) and a disconnector (1 b) (1 d), being actuated in both cases by at least one actuating element (3) which, by means of a single operation of the operating mechanism (32), allows performing the breaking - connection - sectioning functions.