Directional Coupler for Fault Location on Conductors
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Solution Overview
Problem
Existing fault location devices in electrical networks face challenges due to complex and costly designs, particularly with large and heavy chokes that require network disconnection for installation, leading to operational disruptions and increased complexity.
Innovation Solution
A directional coupler using a capacitor to block high-frequency test pulses and echoes, allowing for a small, lightweight, and inexpensive design that operates without network interruption, utilizing Rogowski coils for non-contact inductive coupling and decoupling, and a capacitor to suppress reflections from the rear network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer with inductive coupling is used to couple test pulses to the line, then the test pulses can be directed towards the fault location, but the device becomes large, heavy, and expensive
Solution Approach 1:
The patent replaces the mechanical/physical transformer coupling system with an electronic switching system. Instead of using a transformer to inductively couple test pulses to the line, the invention uses electronic switches (transistors or thyristors) to directly connect the pulse generator to the line, eliminating the need for heavy magnetic coupling components while maintaining the ability to direct test pulses toward the fault location.
2Reliability
If a choke is connected in series with the line to block reflections, then pulse reflections from the rear network are prevented, but the line must be interrupted and power supply stopped
Solution Approach 1:
The patent employs dynamic switching elements (electronic switches) that can change their state rapidly between conducting and non-conducting modes. During fault location, the switches are activated to block reflections from the rear network, and during normal operation, they remain inactive to maintain continuous power supply, thus providing dynamic adaptability between measurement and operation modes without permanent line interruption.
Solution Approach 2:
The invention implements periodic testing by activating the electronic switches only during brief test pulse intervals rather than continuously. This allows the system to periodically block reflections when needed for measurement while maintaining continuous power supply during normal operation, eliminating the need for sustained line interruption required by permanent choke installations.
3Reliability
If a transformer-based coupling device is used, then test pulses can be coupled to the line, but the circuit becomes exceptionally complex with galvanic connections required
Solution Approach 1:
The patent replaces the complex transformer-based electromagnetic coupling system with a simpler electronic switching system using solid-state devices. This substitution eliminates the need for magnetic cores, windings, and associated galvanic isolation requirements, significantly reducing circuit complexity while maintaining the essential function of coupling test pulses to the line.
4Object-affected harmful factors
If a large choke is used to block high-frequency test pulses, then reflections are suppressed, but the device is too large and heavy for practical application
Solution Approach 1:
The patent replaces the heavy physical choke (inductor) with an electronic switching system that uses active semiconductor devices to achieve the same reflection suppression function. The electronic switches can rapidly change impedance states to block high-frequency test pulses from traveling into the rear network, achieving the same harmful factor suppression without the weight and size of traditional magnetic chokes.
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 trouble-free network operation during installation and maintenance, reducing complexity and weight, and allowing for separate optimization of coupling and decoupling devices, effectively suppressing disturbing reflections and eliminating the need for network disconnection.
Implementation Method 1
The coupling in and out can be purely inductive. It can be designed without contact, so that no modifications to the insulation are necessary.
Implementation Method 2
A directional coupler is proposed, which uses a capacitor to block the rear portion of the network by short-circuiting and thus suppressing the high-frequency components of the test pulse.
Data Source
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AI summary
The invention relates to a device for locating a fault (9) on a conductor (4) of an electrical transmission line (1) having at least one phase conductor (4) and at least one counter conductor (5), comprising a device (11) for coupling at least one test pulse into the conductor (4) and a device (12) for coupling echo pulses reflected at the fault (9) out of the conductor (4), as well as a steering device (17) to couple the pulses at least preferably in the direction forward to the fault (9), wherein the coupling devices (11, 12) are designed to be inductively coupled and the steering device is designed as a capacitor (17) arranged backwards from the coupling devices (11, 12) between the conductor (4) and the counter conductor (5).