Parallel Breaking Load Switch With Cam-Driven Vacuum Interruption
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Solution Overview
Problem
Existing medium-voltage circuit breakers face challenges with the use of vacuum interrupters due to their bulkiness and high cost, limited flexibility in arrangement, and precise kinematic connections, necessitating improved designs for lower accuracy, longer breaking distance, and flexible over-travel in disconnection.
Innovation Solution
A parallel breaking load switch design incorporating a stationary contact, moving contact, vacuum interrupter, and cam assembly, allowing for a rotating small contact to actuate the vacuum interrupter with a linear movement of at least 7 mm, facilitated by a cam assembly with a leading and guiding groove, and a torsional spring for elastic potential energy release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vacuum interrupter is used in a medium-voltage circuit breaker, then arc extinguishing capability is improved, but device size and cost increase
Solution Approach 1:
The circuit breaker is divided into two separate functional parts: a main switch for normal current conduction and a vacuum interrupter for arc extinguishing. The vacuum interrupter is arranged in a bypass circuit that is only activated during disconnection operations, allowing it to be smaller and less expensive while maintaining effective arc control.
Solution Approach 2:
The bypass circuit with the vacuum interrupter is pre-configured and ready to activate automatically when disconnection is needed. The movable portion closes the bypass circuit containing the vacuum interrupter before the main circuit current is interrupted, ensuring the vacuum interrupter is prepared to handle the arc extinguishing function.
2Volume of moving object
If the vacuum interrupter is arranged in a bypass circuit, then device size is reduced, but kinematic connection precision requirements increase
Solution Approach 1:
A cam assembly with a small contact rotatable around a rotating axis is introduced as an intermediary mechanism between the movable portion and the vacuum interrupter. This cam assembly translates the rotational motion of the movable portion into precise linear movement of the vacuum interrupter's movable switch contact, reducing the direct kinematic connection precision requirements while maintaining reliable operation.
3Object-generated harmful factors
If the movable portion closes the bypass circuit before interrupting main circuit current, then arc generation in main switch is avoided, but current interruption timing complexity increases
Solution Approach 1:
The system dynamically transitions between two operational states: during normal operation, the main circuit carries current while the bypass circuit remains open; during disconnection, the bypass circuit closes to redirect current through the vacuum interrupter before the main circuit is interrupted. This dynamic reconfiguration eliminates arcs in the main switch while managing timing complexity through the mechanical cam assembly.
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 design achieves reliable and cost-effective disconnection with fewer components, reduced assembly errors, and improved reliability by allowing flexible setting of over-travel and breaking distance, while avoiding arcing and using less expensive insulation gases.
Implementation Method 1
the vacuum interrupter is the most effective in extinguishing arc current
Implementation Method 2
a cam assembly, wherein the cam assembly is provided with a small contact capable of rotating around the rotating axis
Implementation Method 3
a torsional spring for elastic potential energy release
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Present disclosure relates to a parallel breaking load switch, which includes: - a stationary contact; - a moving contact, wherein the moving contact is configured to be capable of rotating around a pivot axis among a closed position, a commutation position and a breaking position; - a vacuum interrupter, wherein the stationary contact is electrically connected with a fixed switch contact in the vacuum interrupter; and - a cam assembly, wherein the cam assembly is provided with a small contact capable of rotating around the pivot axis; wherein a moving end of a movable switch contact can be guided and operatively connected to the cam assembly, and a travel of the linear movement is not less than 7 mm. Thus, a relatively long breaking distance can be realized, and technical requirements such as over-travel can be set flexibly. Present disclosure also relates to a medium-voltage switchgear with the parallel breaking load switch.