Rogowski Converter Wire Breakage Detection in Circuit Breakers
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Solution Overview
Problem
The existing circuit breakers with Rogowski converters face limitations in using the same electronic trip unit (ETU) for various switch rated currents due to restricted input ranges, leading to inadequate measurement capabilities and potential misinterpretation of wire breakages when applying DC voltage.
Innovation Solution
Incorporating a digital/analog converter coupled to a communication bus allows for digitally prescribing the DC voltage, enabling the data processing device to set a switch-rated-current-dependent gain factor and ensure consistent offset detection across different gain factors, thereby expanding the measurement range and universality of the ETU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed gain factor is used in the amplifier stage, then the circuit breaker can reliably detect wire breakages for a specific switch rated current, but the electronic trip unit cannot be universally applied across different switch rated currents
Solution Approach 1:
The patent implements dynamic adjustment of the gain factor in the amplifier stage based on the switch rated current. The data processing device determines the appropriate gain factor corresponding to the detected switch rated current and configures the amplifier stage accordingly, allowing the system to adapt to different current ranges while maintaining accurate offset detection for wire breakage checking
Solution Approach 2:
The patent changes the electrical parameters (gain factor) of the amplifier stage according to the switch rated current. By adjusting the gain factor to match different current levels, the system ensures that the offset voltage from the Rogowski converter remains within the detectable range of the data processing device across various rated currents
2Adaptability or versatility
If the data processing device has a restricted input range, then the measurement system is simpler, but the ETU cannot be used for different switch rated currents without customization
Solution Approach 1:
The patent makes the voltage application device universal by enabling it to handle multiple switch rated currents through software configuration rather than hardware customization. The data processing device stores multiple gain factors corresponding to different rated currents and selects the appropriate one based on detection, allowing a single ETU design to serve multiple current ranges
Solution Approach 2:
The patent replaces physical customization (mechanical/electrical configuration for different current ranges) with software-based configuration. Instead of requiring different hardware setups for different rated currents, the system uses digital storage and retrieval of gain factors, substituting mechanical complexity with programmable control
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 function effectively across a wide range of switch rated currents without customization, ensuring accurate detection of wire breakages and reliable operation by maintaining consistent offset levels regardless of gain factors.
Implementation Method 1
a Rogowski converter is used to measure the current level; this is a coil without an iron core, i.e. an air-core inductor or generally a coil wound on a plastic body. The Rogowski converter has an amplification stage arranged downstream of it for amplifying output signals from the Rogowski converter, that is to say for amplifying the voltage induced in the Rogowski converter on account of a change in the current level through the power line.
Implementation Method 2
the device for applying a DC voltage to the Rogowski converter therefore comprises a digital/analog converter which is coupled to a communication bus which can be used to digitally prescribe the value for the DC voltage for the purpose of the conversion by the digital/analog converter.
Data Source
AI summary
A circuit breaker is disclosed. A Rogowski converter is checked for wire breakage by applying a voltage to the Rogowski converter which is output by a digital/analog converter in response to a digital signal. The digital signal is dependent on the switch rated current of the circuit breaker.