Adjustable Circuit Breaker Tripping Curve for Selective Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Circuit breakers face challenges in achieving selective tripping behavior due to overlapping characteristic curves with fuses, limiting their ability to detect faults and short-circuit currents effectively in electrical power systems.
Innovation Solution
A circuit breaker design with an adjustable current/period limit value characteristic curve, allowing for a range of current limit values and periods that decrease with increasing current, enabling precise control for selective tripping and closer staggering with fuses, along with an adjustable second current limit value that can be set as a multiple of the rated current or other limit values, enhancing adjustability and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If circuit breakers use fixed characteristic curves for tripping, then the device structure is simple, but the ability to achieve selective tripping with fuses is limited due to overlapping curves
Solution Approach 1:
The patent applies dynamics by making the tripping characteristic curve adjustable rather than fixed. The control unit allows modification of the characteristic curve parameters (such as time delay and current threshold) to match different protection requirements. This enables the circuit breaker to adapt its tripping behavior dynamically, achieving selective tripping with fuses by adjusting the characteristic curve to avoid overlapping, thus improving reliability while managing device complexity through software-based adjustment mechanisms.
2Adaptability or versatility
If the current/period limit value characteristic curve is made adjustable, then selectivity and protection functions are improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by allowing adjustment of key parameters in the current/period limit value characteristic curve, such as the time delay parameter and current threshold parameter. The control unit stores multiple sets of parameter values corresponding to different tripping characteristics (e.g., D-curve, K-curve, Z-curve). Users can select and adjust these parameters to match specific application requirements, thereby improving adaptability and versatility. The complexity is managed by implementing parameter storage and selection mechanisms in the control unit, which processes the adjusted parameters to generate appropriate tripping signals.
3Ease of manufacture
If circuit breakers have fixed tripping thresholds, then the device is easier to manufacture, but the ability to detect faults effectively across different current ranges is limited
Solution Approach 1:
The patent applies dynamics by replacing fixed tripping thresholds with adjustable thresholds that can be modified according to different fault detection requirements. The control unit allows users to set and adjust current threshold parameters to match specific protection needs, enabling effective fault detection across different current ranges. This improves measurement precision for fault detection while managing manufacturing complexity through standardized adjustable components and software-based threshold configuration.
Data Source
AI summary
A circuit breaker includes a tripping unit for interrupting an electrical circuit, and at least one current sensor for determining the electrical current flowing through the circuit breaker, connected to a control unit and configured such that the determined current is compared with current/period limit values. If a current/period limit value is exceeded, the tripping unit interrupts the electrical circuit. The current/period limit values include an adjustable first current limit value, present for a first period for an interruption; an adjustable second period, during which a second current limit value must be present to effect an interruption; and a range between the first current limit value and the second current limit value, the period decreasing with increasing current limit values in order to effect an interruption. The second current limit value can be adjusted at the circuit breaker.