Inductive Fault Current Detection Without Shunt Losses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting arc faults in electrical circuits are inefficient, leading to increased operating and manufacturing costs due to ohmic losses and complex structures, and are not suitable for both alternating and direct currents.
Innovation Solution
A method and device utilizing inductive coupling between two coils, where the main current path includes a first coil with a large cross-section and a second coil with fewer turns, allowing for rapid detection of faults without additional measuring resistors, reducing ohmic losses and manufacturing costs, and enabling detection of both alternating and direct currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shunt with a measuring resistor is used to detect electrical current, then the electrical current can be measured, but electrical losses occur and operating costs increase
Solution Approach 1:
The patent introduces a magnetic field as an intermediary between the current-carrying conductor and the measurement system. Instead of directly measuring current through a shunt resistor, the invention uses the magnetic field generated by the current to induce a voltage in a secondary coil, which then provides the measurement signal without requiring direct electrical contact or creating ohmic losses in the main current path.
2Measurement precision
If a shunt with a measuring resistor is used to detect electrical current, then the electrical current can be measured, but the measuring resistor heats up requiring cooling
Solution Approach 1:
The magnetic field serves as a mediator that transfers energy from the current-carrying conductor to the measurement coil without thermal contact. This eliminates the heating problem inherent in shunt resistors, as the measurement system remains thermally isolated from the high-current path while still obtaining accurate current information through electromagnetic induction.
3Measurement precision
If current transformers are used to detect electrical current, then the measurement can be performed, but the device complexity and manufacturing costs increase
Solution Approach 1:
The invention extracts only the essential measurement function from complex current transformer designs. By using a simple coil winding around or near the current-carrying conductor, the system achieves current measurement capability without the need for complex transformer cores, multiple windings, or sophisticated calibration mechanisms, thereby reducing device complexity while maintaining measurement accuracy.
4Measurement precision
If measuring transformers are used to detect direct current, then the measurement can be performed, but the device complexity and manufacturing costs increase
Solution Approach 1:
For direct current measurement, the invention uses the magnetic field as an intermediary that can detect both AC and DC currents uniformly. The magnetic field generated by direct current induces a measurable effect in the secondary coil, eliminating the need for separate AC/DC measurement systems or complex rectification circuits, thereby simplifying the device while expanding its measurement capabilities.
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
The solution reduces operating costs by eliminating ohmic losses, decreases manufacturing costs through simplified components, and enhances detection speed and robustness by providing immediate changes in inductance and current measurement, effectively addressing the inefficiencies of existing arc fault detection methods.
Implementation Method 1
The first coil is inductively coupled to a second coil. A electrical voltage is applied to the second coil. An electrical current resulting from the applied electrical voltage through the second coil is measured.
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method (26) for detecting a current, caused by a fault, in a main current path (4) which has a first coil (10) which is inductively coupled with a second coil (12). An electric voltage is applied at the second coil (12), and an electric current resulting from the second coil (12) is detected. The electric current is compared with a limit value, and a conclusion regarding the existence of a fault is drawn subject to the comparison. The invention further relates to a device (8) for detecting a current caused by a fault, and to a circuit breaker (2).