Circuit Breaker Extended Instantaneous Protection
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Solution Overview
Problem
Existing circuit breakers lack effective mechanisms for extended instantaneous protection, which is crucial for managing high fault currents and ensuring reliable power distribution, especially in systems with varying load conditions such as those with utility transformers or added generators/motors.
Innovation Solution
A circuit breaker system incorporating a Rogowski coil current transformer and a microprocessor that monitors alternating current levels and initiates tripping based on predetermined thresholds and time intervals, providing extended instantaneous protection by delaying tripping until a set number of current cycles is exceeded, thus preventing unnecessary power disruptions and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circuit breaker trips immediately when fault current exceeds the withstand level, then protection reliability is improved, but unnecessary power disruptions occur and the circuit breaker cannot operate within its full interrupting rating
Solution Approach 1:
The circuit breaker employs dynamic trip characteristics that adapt to different fault conditions. The microprocessor monitors current over multiple cycles and dynamically adjusts the tripping decision based on whether the fault is temporary (e.g., lightning strike) or persistent. This allows the breaker to maintain reliability by tripping for true faults while avoiding unnecessary disruptions for transient conditions.
Solution Approach 2:
The system performs preliminary monitoring of current levels over a predetermined number of cycles before initiating tripping. This preliminary action allows the circuit breaker to assess the nature of the fault and determine whether immediate tripping is necessary, thereby preventing premature disruptions while ensuring protection when needed.
2Ease of operation
If the circuit breaker uses a predetermined tripping threshold, then operation simplicity is improved, but the circuit breaker cannot adapt to varying load conditions such as utility transformers or added generators/motors
Solution Approach 1:
The circuit breaker uses dynamic trip curves that can adapt to different system configurations. The microprocessor monitors current characteristics over multiple cycles and adjusts tripping thresholds based on the detected load pattern, allowing the same device to accommodate utility transformers, generators, motors, and other varying conditions while maintaining simple operation for the end user.
Solution Approach 2:
The system changes operational parameters (tripping thresholds and time delays) based on detected system conditions. The microprocessor analyzes current waveforms and adjusts the effective trip settings to match the specific configuration, whether it involves utility transformers, distributed generators, motor loads, or other equipment, thereby achieving versatility without complicating user operation.
3Productivity
If the circuit breaker delays tripping until a set number of current cycles are exceeded, then unnecessary power disruptions are prevented, but the response time to actual faults is extended
Solution Approach 1:
The time delay before tripping is dynamically adjusted based on the detected fault characteristics. For severe faults that clearly exceed the interrupting rating, the microprocessor initiates tripping after minimal cycles. For marginal or temporary overcurrent conditions, the delay is extended to allow assessment of whether the condition is transient, thereby optimizing both response time and prevention of unnecessary disruptions.
Solution Approach 2:
The circuit breaker performs preliminary monitoring for a predetermined number of cycles to confirm the persistence of the fault condition before initiating tripping. This preliminary assessment period ensures that transient conditions do not trigger false trips, while the microprocessor's rapid analysis capability minimizes the actual delay for genuine faults, balancing continuity with responsive protection.
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
This solution enables the circuit breaker to operate within its full interrupting rating even when fault currents exceed its withstand level, improving power transmission reliability by coordinating trips and preventing downstream faults from affecting non-faulted circuits.
Implementation Method 1
a Rogowski coil current transformer and a microprocessor that monitors alternating current levels
Data Source
AI summary
Certain exemplary embodiments can comprise an apparatus comprising: a current transformer adapted to provide a signal correlated to an amperage of an alternating current of a first phase of an electric circuit, the alternating current flowing through a circuit breaker; and a microprocessor adapted to receive the signal from said current transformer, and to cause the circuit breaker to trip responsive to the signal exceeding a predetermined threshold.