Solid-State Circuit Interrupter Turn-On Control for Fast Fault Isolation
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Solution Overview
Problem
Conventional circuit interrupters are slow to react to fault conditions due to their electromechanical construction, leading to hazardous situations such as arc-flashes and inadequate protection against over-current conditions, with high variability in response times and current trip limits.
Innovation Solution
The development of solid-state circuit interrupter devices that utilize a solid-state switch and mode control circuit to quickly isolate faults, featuring a self-bias turn-on threshold voltage control mode and forced turn-off control mode, along with an air-gap electromagnetic switch for enhanced safety and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electromechanical circuit interrupters are used, then high isolation capability is achieved once tripped, but slow reaction time results in inadequate protection against arc flashes
Solution Approach 1:
The patent replaces the electromechanical switching mechanism with a solid-state switch controlled by a mode control circuit. The solid-state switch uses electronic field effects rather than mechanical contact movement, enabling reaction times in the microsecond range compared to millisecond times for electromechanical devices. This substitution maintains the circuit interrupter's ability to isolate faults while dramatically improving response speed to prevent arc flash hazards.
Solution Approach 2:
The patent changes the operational parameters of the circuit interrupter by implementing a mode control circuit that dynamically adjusts the switching characteristics. The mode control circuit transitions the solid-state switch between different operational modes (normal operation, fault detection, and isolation modes) based on real-time monitoring of electrical parameters such as current magnitude and voltage conditions, enabling both rapid response and reliable isolation.
2Device complexity
If conventional electromechanical circuit interrupters are used, then device simplicity is maintained, but large variations in trip time and current trip limit occur due to physical factors
Solution Approach 1:
The patent eliminates the mechanical components (bimetallic strips, electromagnetic coils, moving contacts) that cause variability in trip characteristics. The solid-state switch and mode control circuit provide electronic control with precise, repeatable timing and current threshold detection. This electronic approach removes the influence of mounting stresses and temperature variations that affect electromechanical devices, delivering consistent trip time and current trip limit across all units.
Solution Approach 2:
The mode control circuit incorporates feedback mechanisms that continuously monitor electrical parameters and adjust switching decisions accordingly. By sensing actual current and voltage conditions in real-time, the control circuit compensates for any environmental variations and ensures precise, consistent tripping characteristics. This feedback loop enables the device to maintain accurate protection thresholds regardless of external conditions.
3Ease of manufacture
If conventional electromechanical circuit interrupters are used, then manufacturing simplicity is maintained, but coordination between multiple circuit interrupters becomes almost impossible due to high variability
Solution Approach 1:
The patent replaces electromechanical components with solid-state electronics that offer programmable and adjustable characteristics. The mode control circuit can be configured with specific trip thresholds and timing characteristics, allowing multiple circuit interrupters to be coordinated within a system. This electronic configurability enables selective coordination where upstream devices have longer trip delays than downstream devices, creating a hierarchical protection scheme that was impossible to achieve consistently with variable electromechanical devices.
Solution Approach 2:
The patent introduces dynamic adjustability to the circuit interrupter through the mode control circuit. The control circuit can adapt its tripping characteristics based on system requirements, enabling coordination between multiple devices. This dynamic capability allows the protection system to be optimized for specific applications, with adjustable time-current characteristics that can be matched to the protection needs of different circuit levels and load types.
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
These devices provide rapid and precise fault isolation, reducing the risk of hazardous events like arc-flashes and improving protection by ensuring consistent and swift response to over-current conditions, even exceeding the trip current rating.
Implementation Method 1
The solid-state switch is configured to be placed in one of (i) a switched-on state to provide an electrical connection in an electrical path between the line input terminal and the load output terminal, and (ii) a switched-off state
Implementation Method 2
an air-gap electromagnetic switch for enhanced safety and precision
Data Source
AI summary
A circuit interrupter includes a solid-state switch and a mode control circuit. The solid-state switch is serially connected between a line input terminal and a load output terminal of the circuit interrupter. The mode control circuit is configured to implement a first control mode and a second control mode to control operation of the circuit interrupter. The first control mode is configured to generate a self-bias turn-on threshold voltage for the solid-state switch during power-up of the circuit interrupter, while maintaining the solid-state switch in a switched-off state until the self-bias turn-on threshold voltage is generated. The second control mode is configured to disrupt the self-bias turn-on threshold voltage and place the solid-state switch into a switched-off state.