Hybrid Switching Device Arc Suppression via Semiconductor Commutation
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Solution Overview
Problem
Existing switching devices face challenges in preventing unwanted switching arcs, particularly during the switch-on process, which can lead to contact welding and reduced functional reliability, especially when handling high DC currents and low-frequency AC currents.
Innovation Solution
A hybrid switching arrangement is modified to include a semiconductor switch connected in parallel, which is briefly activated during the mechanical contacting process to suppress arcing, with the commutation time adjusted based on the mechanical contact arrangement to minimize load on the semiconductor switch and prevent excessive arcing stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor switch is activated during mechanical contacting to suppress arcing, then contact welding is prevented and functional reliability is improved, but the semiconductor switch experiences increased current load and thermal stress
Solution Approach 1:
The semiconductor switch is activated in advance before the mechanical contacts fully close, during the contacting process when arcing occurs. This preliminary action suppresses the arc formation at the contacts by providing an alternative low-impedance path for the current, preventing contact welding while the mechanical contacts are still closing
Solution Approach 2:
The activation time of the semiconductor switch is dynamically adjusted based on the closing time of the mechanical contact arrangement. The control unit waits for a specified period after initialization before activating the semiconductor switch, allowing adaptation to different mechanical contact characteristics and optimizing the timing for arc suppression while minimizing unnecessary semiconductor conduction time
2Reliability
If the semiconductor switch is activated early to prevent arcing, then contact protection is improved, but the current load on the semiconductor increases unnecessarily
Solution Approach 1:
The semiconductor switch is activated in advance during the mechanical contacting process to establish an alternative current path before the mechanical contacts fully close, preventing arc formation and contact damage
Solution Approach 2:
The control unit automatically determines the activation time based on the closing time of the mechanical contact arrangement, adapting to the specific mechanical contact characteristics without requiring external intervention or fixed timing parameters
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 approach reduces the risk of arcing and extends the electrical service life of switching devices by ensuring reliable commutation and minimizing thermal load on the semiconductor switch, thereby enhancing functional reliability and longevity.
Implementation Method 1
the load current is artificially reduced to zero by the semiconductor via its activation, so that after opening both the reset contact arrangement and the isolating contact arrangement connected in series thereto, reliable galvanic isolation is achieved
Implementation Method 2
after opening both the reset contact arrangement and the isolating contact arrangement connected in series thereto, reliable galvanic isolation is achieved
Implementation Method 3
In such a bouncing process, an arc is briefly formed between the minimally opened contacts. In the case of high arc currents in particular, local melting of the contact surfaces can occur in the area of the base points, which then leads to welding of the two contacts when contact is made again immediately afterwards
Data Source
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AI summary
The invention relates to a switching device for conducting and interrupting electrical currents, comprising a first mechanical contact assembly (10), a semiconductor switch (20) connected in parallel to the first mechanical contact assembly, a second mechanical contact assembly (30) connected in series to the first mechanical contact assembly, and switching electronics (50) designed to switch the semiconductor switch (20) on and off. According to the invention, the switching electronics (50) are designed such that, during a closing process of the first mechanical contact assembly (10), they switch on the semiconductor switch (20) at the end of a first specified time period t-0 after the initialisation of the switching electronics (50), and they switch same off again at the end of a second specified time period t-1, wherein the first specified time period t-0 is adjusted by the switching electronics (50) according to the first mechanical contact assembly (10).