Residual Current Circuit Breaker Voltage-Independent Test
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Solution Overview
Problem
Residual current circuit breakers require different test resistors for various mains voltage ranges, limiting their applicability and increasing the number of device variants needed.
Innovation Solution
Incorporating a current source with a series connection of two transistors, specifically depletion-type MOSFETs, which allows for a voltage-independent test current generation, enabling a wider range of applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a test resistor is used in the test circuit, then the test current can be generated, but the device requires different test resistors for various mains voltage ranges, increasing device complexity and reducing adaptability
Solution Approach 1:
The patent replaces the voltage-dependent test resistor with a current source that generates a predetermined test current independent of mains voltage. This parameter change from voltage-based to current-based testing eliminates the need for multiple device variants across different voltage ranges, directly resolving the contradiction between adaptability and device complexity
Solution Approach 2:
The current source is designed to provide a universal test current that works across all mains voltage ranges without requiring device-specific configurations. This single universal test circuit replaces multiple voltage-specific test resistor configurations, enabling one device design to serve multiple voltage applications
2Reliability
If a test resistor is used to generate test current, then the functionality can be tested, but the device may experience overload during voltage peaks
Solution Approach 1:
The current source is designed with built-in current limiting capability that prevents excessive current flow before voltage peaks can cause damage. By establishing a maximum current threshold in advance, the circuit proactively protects against overload conditions that would otherwise occur during voltage transients or peaks
Solution Approach 2:
The current source uses simple electronic components including transistors and resistors that can be easily replaced if needed, providing a cost-effective solution for protecting against voltage peaks without requiring expensive complex protection circuits
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 extends the voltage range of residual current circuit breakers, reduces the need for device variants, ensures safe current limitation, and avoids overload during voltage peaks, while simplifying the design and reducing costs.
Implementation Method 1
Incorporating a current source with a series connection of two transistors, specifically depletion-type MOSFETs, which allows for a voltage-independent test current generation
Implementation Method 2
an earth fault detection circuit including a zero-phase current transformer, a test winding and an earth fault detection winding
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a residual current circuit breaker for an electrical circuit, comprising a summation current transformer for determining a differential current of the electrical circuit, a switching lock with contacts for interrupting the electrical circuit, and a tripping circuit connected to the summation current transformer and the switching lock, configured such that the switching lock is activated when a differential current limit is exceeded, thereby interrupting the electrical circuit. A test circuit with a test button for checking the functionality of the residual current circuit breaker includes a current source.