Switchgear Unit Thermal Fuse Arc Extinguishing
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Solution Overview
Problem
Existing switchgear units for high DC voltages face challenges in reliably and safely interrupting direct current between a PV generator and an inverter, particularly in extinguishing arcs that are not automatically extinguished, requiring manual intervention and being prone to faults due to missing or defective components.
Innovation Solution
A switchgear unit with a mechanical contact system and a thermal fuse that trips when the arc-generated heat exceeds the melting point, independent of current level, using a prestressed spring element to automatically interrupt the circuit and extinguish arcs without manual activation, featuring a melting location and conductive materials that allow for reliable and economic manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical switches are used for load isolation, then DC isolation is produced between the electrical device and direct current source, but the arc produced when contacts are opened under load requires manual intervention and is prone to faults
Solution Approach 1:
The thermal fuse is designed to automatically detect arc-generated heat and trip the isolating apparatus without manual intervention. The melting location directly senses the thermal state and autonomously initiates circuit interruption, making the system self-protecting against arc faults.
Solution Approach 2:
The patent replaces manual mechanical operation with an automated thermal-mechanical system. The thermal fuse converts thermal energy from the arc into mechanical motion through melting, which then triggers the isolating apparatus to open the circuit automatically, eliminating the need for manual switching.
2Object-affected harmful factors
If arc extinguishing apparatuses with permanent magnets are used, then arcs are moved and extinguished, but the system is complex and prone to faults from missing or defective components
Solution Approach 1:
The patent extracts the essential function of arc detection and response from the complex magnetic blowout system. By isolating the thermal fuse as a separate, simple component that directly senses arc heat, the system eliminates the need for permanent magnets, arc conducting pieces, and complex magnetic field generation apparatuses.
Solution Approach 2:
The thermal fuse is designed as a simple, inexpensive, single-use component. The melting location is a consumable element that sacrifices itself by melting to trigger the protective action, replacing expensive and complex permanent magnetic components with a cheap thermal response mechanism.
3Extent of automation
If thermal fuse with melting location is used, then automatic tripping occurs independent of current level, but the melting location must be precisely positioned in the conductor path
Solution Approach 1:
The melting location is integrated directly into the conductor path structure itself, merging the thermal sensing function with the current-carrying element. This integration eliminates the need for separate positioning mechanisms and ensures the melting location is automatically in the correct position within the electrical circuit.
Solution Approach 2:
The conductor path serves as an intermediary that both carries the current and positions the melting location. The thermal energy from the arc is transferred through this intermediary element to the melting location, which then triggers the protective action, simplifying the overall positioning requirements.
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
Ensures safe and reliable DC isolation between the PV generator and inverter, preventing damage from arcs and allowing for quick system interruption, even in the absence of current overloads, while being cost-effective and suitable for a range of voltage applications.
Implementation Method 1
The thermal fuse has a melting location which is arranged in the conductor path and which is connected first to the contact system and second via a moving conductor section to the first connection. The isolating apparatus is tripped and the connection between the conductor section and the contact system at the melting location is broken when the arc has caused the melting temperature of the melting location to be reached or exceeded.
Implementation Method 2
A switchgear unit with a mechanical contact system and a thermal fuse that trips when the arc-generated heat exceeds the melting point, independent of current level, using a prestressed spring element to automatically interrupt the circuit
Data Source
AI summary
A switchgear unit switches high DC voltages, particularly for interrupting of direct current between a direct current source and an electrical device. The switchgear unit contains two connections which project from a housing and which are electrically conductively coupled by a conductor path, a contact system which is arranged between the first and second connections and an isolating apparatus that can be tripped by a thermal fuse. The thermal fuse contains a melting location which is arranged in the conductor path and which is connected first to the contact system and second via a moving conductor section to the first connection. The isolating apparatus is tripped and the connection between the conductor section and the contact system is broken at the melting location when an arc produced when the contact system is opened has caused the melting temperature of the melting location to be reached or exceeded.