Circuit Interrupter Interlock for Manual Isolation Switching
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Solution Overview
Problem
Solid state circuit interrupters face issues where the isolation switch cannot be manually switched from the ON state to the OFF state without auxiliary power, leading to impaired functionality and potential current leakage.
Innovation Solution
Incorporation of a physical interlock apparatus that resists manual movement of the isolation switch from the ON state to the OFF state until certain conditions are met, combined with an electronic interlock that synchronizes the states of the solid state switch and isolation switch to prevent unintended state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the isolation switch is made manually operable without auxiliary power, then the ease of operation is improved, but the risk of unintended state changes and potential damage increases
Solution Approach 1:
A physical interlock mechanism is introduced as an intermediary between the manual operator and the isolation switch. This interlock requires a key or tool to disengage before the isolation switch can be manually operated, ensuring that proper procedures are followed and preventing unintended state changes while maintaining manual operability when needed
Solution Approach 2:
The system provides self-protection through the interlock mechanism that automatically prevents unsafe operations. The interlock is designed to physically block the isolation switch from being moved unless specific conditions are met, making the system self-protecting without requiring external supervision or auxiliary power
2Loss of time
If the isolation switch can be manually moved from ON to OFF state without auxiliary power, then the loss of time in serviceable situations is reduced, but harmful factors increase due to potential current leakage
Solution Approach 1:
The solid state switch is required to be in the OFF state before the isolation switch can be manually operated. This preliminary condition ensures that no current is flowing through the solid state devices when the isolation switch is moved, eliminating the risk of current leakage while allowing quick manual operation when the circuit is already de-energized
Solution Approach 2:
The physical interlock serves as a mediator that enforces the proper sequence of operations. It mechanically prevents the isolation switch from being moved unless the solid state switch is in the correct state, ensuring safety while enabling rapid service when conditions are appropriate
3Reliability
If an electronic interlock is added to synchronize switch states, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex electronic interlock systems with a simpler mechanical interlock mechanism. The physical interlock uses mechanical linkages, latches, and blocking structures to enforce proper switch state sequences, achieving reliable synchronization with fewer components and lower complexity than electronic alternatives would require
Data Source
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AI summary
A solid state circuit interrupter provides structures which can manually move an isolation switch of a pole from the ON state to the OFF state without the use of auxiliary power but that advantageously additionally provides an interlock apparatus that avoids manually moving the isolation switch from the ON state to the OFF state until certain conditions exist. One such condition is to ensure that some action is taken, such as by switching a physical interlock between one state and another state. Such a change in state of the physical interlock might additionally result in a change in state of an electronic interlock that would resist the solid state switch being moved to its ON state while the isolation switch is capable of being manually switched to its OFF state. The physical interlock might additionally resist the isolation switch from being manually switched into its ON state.