Fault Current Detection Device with Saturation Control
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Solution Overview
Problem
Existing fault current detection devices in electrical installations are not sufficiently sensitive to direct or pulsed currents, and using multiple magnetic circuits to mitigate saturation issues leads to bulkiness and increased cost.
Innovation Solution
A fault current detection device utilizing a single magnetic circuit with a current sensor, secondary winding, generator, measuring circuit, processing circuit, and control circuit to detect saturation and generate fault signals, allowing for economical and compact detection of fault currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple magnetic circuits are used to mitigate saturation issues, then reliability is improved, but device complexity and size increase
Solution Approach 1:
The control circuit preliminarily detects the magnetic state of the single magnetic circuit by measuring the voltage across the secondary winding. When saturation is detected, it generates a fault signal before the fault current can cause damage, preventing the need for multiple magnetic circuits while maintaining detection reliability.
Solution Approach 2:
The patent introduces an intermediary control circuit that monitors the magnetic circuit's state through voltage measurement. This intermediary mechanism enables a single magnetic circuit to provide reliable detection by detecting saturation conditions, eliminating the need for multiple magnetic circuits.
2Reliability
If the magnetic circuit is oversized to avoid saturation at high fault currents, then reliability is improved, but device size and cost increase
Solution Approach 1:
The patent replaces the mechanical approach of oversizing the magnetic circuit with an electrical detection approach. The control circuit uses voltage measurement across the secondary winding to detect magnetic saturation, allowing a compact magnetic circuit to reliably detect high fault currents without physical oversizing.
Solution Approach 2:
The patent changes the detection parameter from physical magnetic field measurement to voltage measurement across the secondary winding. This parameter change enables the use of a compact magnetic circuit while maintaining the ability to detect high fault currents through electrical signal analysis rather than physical dimensioning.
3Device complexity
If a single magnetic circuit is used, then device size and cost are reduced, but detection precision deteriorates due to saturation
Solution Approach 1:
The control circuit continuously monitors the voltage across the secondary winding, providing feedback on the magnetic circuit's saturation state. When saturation is detected through voltage threshold comparison, the system generates a fault signal, maintaining detection precision with a single magnetic circuit by using feedback-based saturation detection.
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
Enables effective detection of alternating, direct, or pulsed fault currents with reduced size and cost, ensuring reliable operation even at high fault current thresholds, and activates appropriate safety mechanisms.
Implementation Method 1
a current sensor formed by a magnetic circuit (11) crossed by the current line (5), the latter forming a primary, said sensor comprising a first secondary winding (12) wound on the magnetic circuit (11)
Implementation Method 2
a generator (13) connected to said first secondary winding (12) to deliver an electrical signal AC to it
Implementation Method 3
to provide a second fault signal when said electrical signal is representative of saturation of the magnetic circuit
Data Source
Figure 1
Figure 2a~2c
Figure 3
AI summary
A device for detecting a fault current flowing in a current line (5) of an electrical installation comprises: - a magnetic circuit (11), through which the current line (5) passes, having a secondary winding (12), - a generator (13) connected to the winding (12) to supply it with an electrical signal, - a current measurement circuit (14) for the current flowing in the winding (12), - a processing circuit (15) for providing a fault signal when the current in the winding (12) exceeds a predetermined threshold. The device includes a control circuit (22) arranged to provide a second fault signal (25) in the event of saturation of the magnetic circuit (11) or failure of the generator (13). The invention also relates to a residual current protection device and the assembly of several residual current protection devices.