Time-Offset Series Switches for Permanent Inductive Load Isolation
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Solution Overview
Problem
High-current, high-voltage switches used for disconnecting circuits with inductive loads face challenges in maintaining insulation resistance after disconnection, leading to potential re-conductivity and switch destruction due to high energy arcs and chemical conversion of extinguishing agents.
Innovation Solution
A dual-switch system where a high-current, high-voltage switch with an extinguishing agent is used initially to dissipate the majority of the inductive energy, followed by a second switch with lower energy handling capabilities to ensure safe and permanent disconnection, with the second switch activated after the first has absorbed sufficient energy to prevent destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single high-current, high-voltage switch with extinguishing agent is used to disconnect circuits with high inductive loads, then the circuit can be interrupted initially, but the switch becomes conductive again after cooling and cannot guarantee permanent safe separation
Solution Approach 1:
The single switch is divided into two separate switches connected in series. The first switch (S1) handles the initial high-energy interruption, while the second switch (S2) ensures permanent disconnection. This segmentation allows each switch to be optimized for its specific function, with S1 designed to withstand high energy input and S2 designed for reliable long-term insulation.
Solution Approach 2:
The first switch S1 performs the preliminary action of absorbing the majority of inductive energy through its extinguishing agent before the second switch S2 operates. This preliminary energy dissipation reduces the energy burden on S2, allowing it to maintain insulation resistance permanently without being overwhelmed by the full inductive energy load.
2Power
If a switch with extinguishing agent is used to withstand high energy input, then the circuit can be interrupted at high voltage and current, but the extinguishing agent becomes electrically conductive when plasma cools down
Solution Approach 1:
The switching function is segmented between two switches: S1 equipped with extinguishing agent for high-power interruption, and S2 without extinguishing agent for reliable insulation. This separates the high-power handling function from the insulation maintenance function, allowing each component to be optimized for its specific role.
Solution Approach 2:
The first switch S1 acts as an intermediary that absorbs the harmful inductive energy through its extinguishing agent before it can affect the second switch S2. This intermediary approach protects S2 from energy overload while maintaining the benefits of using extinguishing agents in S1 for high-power switching.
3Reliability
If the second switch is activated too early, then it may be destroyed by high energy arcs, but if activated too late, the first switch may become conductive again
Solution Approach 1:
The control unit continuously monitors the energy input into the first switch and uses this feedback information to determine the optimal moment to activate the second switch. This feedback mechanism ensures S2 is activated at the precise moment when enough energy has been absorbed by S1 to protect S2, but not so late that insulation resistance deteriorates.
Solution Approach 2:
The system dynamically changes the operational parameters of the two switches based on real-time conditions. The control unit adjusts the timing of S2 activation based on the energy absorption state of S1, transforming a static switching problem into a dynamic, condition-based control system that optimizes both safety and timing.
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 allows for permanent and safe disconnection of circuits with high inductive loads by distributing the energy load between the two switches, preventing re-conductivity and switch destruction, and enabling the use of lower-cost, lower-capacity switches for the second stage.
Implementation Method 1
the first switch/switching group is a high-current high-voltage switch which has an extinguishing agent in its interior in the region of the isolating element, by the separation of which the circuit is separated
Implementation Method 2
the cause of the formation of an arc is the energy stored in the circuit inductance in the form of a magnetic field at the moment of current separation
Implementation Method 3
the control unit is designed such that the second switch/switching group is transferred from the closed state to the disconnected state when so much energy has been absorbed in the first switch/switching group that the remaining amount of energy introduced into the second switch/switching group does not lead to its destruction
Data Source
Figure 1~2
Figure 3
Figure 4a~4b
AI summary
The invention relates to a device for permanently and reliably disconnecting a circuit with high currents at high voltages with an inductive load. The device comprises a first and a second switch/switching group connected in series, which can be switched from a closed state to a disconnected state to disconnect the circuit, wherein neither switch/switching group is designed to be capable of permanently disconnecting the circuit on its own, and a control unit that controls the second switch/switching group and is designed such that the second switch/switching group is switched from the closed state to the disconnected state after the first switch/switching group.The present invention also relates to a circuit which, in addition to the device according to the invention, also includes a voltage source, a load resistor and an inductive load, as well as a method using the device according to the invention.