Master-Slave Digital Circuit Breakers for Balanced Current Sharing
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Solution Overview
Problem
Parallel electronic circuit breakers often experience unequal current sharing when used in combination, leading to one breaker tripping earlier than the other due to internal tolerancing, resulting in a higher than desired tolerance, which can compromise system reliability.
Innovation Solution
Implementing a master-slave configuration where a master circuit breaker senses and converts current to a digital signal, averages it with a signal from a slave circuit breaker, and controls power switches to terminate power to the load if the average current exceeds a threshold, ensuring synchronized tripping across multiple circuit breakers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parallel circuit breakers are used to increase tolerance, then system reliability is improved, but unequal current sharing occurs due to internal tolerancing causing one breaker to trip earlier
Solution Approach 1:
The patent combines multiple circuit breakers into a single integrated unit with shared current sensing and control electronics. The breakers are electrically connected in parallel but controlled by a unified system that measures total current and distributes tripping commands synchronously, eliminating the current sharing inequality problem while maintaining enhanced reliability through redundancy
2Device complexity
If circuit breakers are used as stand-alone units, then device complexity is reduced, but tolerance is lower compared to parallel configuration
Solution Approach 1:
The circuit breaker unit is designed with multi-functionality to operate effectively both as a stand-alone device and in parallel configurations. The integrated control system automatically adapts to the operating mode, providing appropriate tolerance levels for each configuration while maintaining consistent device complexity through standardized modular design
Data Source
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AI summary
A master circuit breaker comprises a first circuit breaker (16a; 116a) that digitally senses a first current to a first load (14; 114); and an input that receives a second digital signal from a slave circuit breaker. The first circuit breaker (16a; 116a) digitally determines an average current based upon the sensed first current and the second digital signal; and the first circuit breaker outputs an output control signal that indicates when the average current is greater than a threshold value. An electrical system includes a first circuit breaker that digitally senses a first current to a first load, and a second circuit breaker that digitally senses a second current to a second load and provides an output to the first circuit breaker. The first circuit breaker determines an average current based upon the first sensed current and the output from the second circuit breaker, and the first and second circuit breakers terminate power to the first and second loads if the average current is greater than a threshold value.