Sequential Switch Interlock to Prevent Arc Discharge
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Solution Overview
Problem
In circuits with both mechanical and power electronic switches connected in series, such as solid-state starters and circuit breakers, arc discharge occurs during the opening and closing of mechanical switches, reducing their service life and reliability due to the lack of sequential interlock between the mechanical and electronic switches.
Innovation Solution
A sequential action device is introduced, which includes a mechanical operating mechanism, a power electronic switch software control circuit, a power electronic switch drive circuit, a triggering device, and a detection circuit. This device ensures that the power electronic switch is turned on only after the mechanical switch is closed and turned off before the mechanical switch is opened, preventing arc discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical switch and a power electronic switch are connected in series without sequential interlock, then the circuit can be simplified and operated independently, but arc discharge occurs during mechanical switch operation, reducing service life and reliability
Solution Approach 1:
The control system performs preliminary actions by detecting the mechanical switch state first, then sequentially controlling the power electronic switch to turn on only after the mechanical switch is confirmed closed, and to turn off before the mechanical switch opens. This preliminary detection and sequential control prevents arc discharge by ensuring the power electronic switch is already off when the mechanical switch begins to open, thereby protecting the mechanical switch without requiring complex interlock hardware.
2Speed
If the power electronic switch is directly controlled without sequential action, then the control response is fast and simple, but arc discharge compromises contact reliability and service life
Solution Approach 1:
The control system implements feedback by continuously detecting the mechanical switch state through detection circuits, then using this feedback information to adjust the power electronic switch control timing. The system monitors whether the mechanical switch is closed or opening, and automatically adjusts the power electronic switch turn-on/turn-off timing accordingly, maintaining fast switching while preventing arc discharge through real-time state-dependent control.
3Duration of action of stationary object
If sequential interlock control is implemented between mechanical and power electronic switches, then arc discharge is prevented and service life is extended, but the control system complexity increases
Solution Approach 1:
The control system acts as an intermediary between the mechanical switch and power electronic switch, mediating their interaction through sequential control. The detection circuit monitors the mechanical switch state, and the control unit translates this into appropriate power electronic switch control signals. This intermediary control function extends mechanical switch service life by preventing arc discharge while maintaining manageable system complexity through modular control architecture.
Data Source
Figure 1~2
AI summary
The present disclosure relates to an electromechanical sequential action device that is capable of sequentially interlocking a mechanical switch and a power electronic switch, where through an action sequence control, the electromechanical mechanism turns on the power electronic switch only after the mechanical switch is closed, and through an advanced travel control, turns off the power electronic switch before opening the mechanical switch, avoiding the problem of arc discharge during closing and opening of the mechanical switch, and improving the service life and connection reliability of the mechanical switch.