Hybrid Switch Actuation for Fast and Low dI/dt Fault Opening
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Solution Overview
Problem
Thomson coil systems are inadequate for switching operations at very slow current change rates (dl/dt <1 kA/ms), as the forces generated are insufficient to separate contacts, while high current change rates require rapid switching.
Innovation Solution
A switch system combining a passive Thomson coil actuator for high current change rates (>1kA/ms) with a spring-loaded actuator for low current change rates (<1 kA/ms), where the Thomson coil system is used for rapid contact separation and the spring system ensures contact opening independent of current change rate, utilizing a latch system to unlock the spring for slow changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a passive Thomson coil actuator is used for high current change rates, then rapid contact separation is achieved, but it becomes inadequate for slow current change rates
Solution Approach 1:
The patent combines a Thomson coil actuator and a spring-loaded actuator into a single hybrid system. The Thomson coil provides rapid response for high dl/dt faults, while the spring-loaded mechanism ensures reliable operation for low dl/dt conditions. Both actuators work together on the same contact assembly, merging their complementary strengths to resolve the contradiction between speed and reliability across different current change rates.
Solution Approach 2:
The system changes the actuation mechanism based on the current change rate parameter. For high dl/dt conditions, the Thomson coil generates sufficient electromagnetic force for rapid contact separation. For low dl/dt conditions, the spring-loaded actuator provides the necessary mechanical force. This parameter-based selection of actuation mode allows the system to maintain both speed and reliability across varying operational conditions.
2Reliability
If a spring-loaded actuator is used for low current change rates, then contact opening is ensured, but response time increases
Solution Approach 1:
The hybrid actuator system dynamically adapts its response based on the detected current change rate. When a low dl/dt condition is detected, the spring-loaded actuator is activated to ensure reliable contact opening. When high dl/dt conditions occur, the Thomson coil takes over to minimize response time. This dynamic adaptation allows the system to optimize between reliability and response time based on real-time conditions.
3Speed
If only a Thomson coil system is used, then rapid switching is achieved for high dl/dt, but the system cannot handle slow overcurrents effectively
Solution Approach 1:
The hybrid actuator system performs multiple functions within a single configuration. The Thomson coil component handles high-speed switching for high dl/dt faults, while the spring-loaded component handles slow-acting overcurrents. This multi-functionality allows the same switch system to effectively handle various current profiles including DC faults, AC faults, and slow overcurrents, greatly enhancing adaptability without sacrificing switching speed capability.
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
The switch system effectively transitions between conductive and nonconductive states for a full spectrum of faulty currents, ensuring quick response to high current changes and handling slower overcurrents, with the spring system achieving an opening gap of 1 mm in about 2 ms, coordinating with other protective devices like fuses.
Implementation Method 1
A current flowing through the coil creates a magnetic field that induces eddy currents into the plate, leading to large repulsive electromagnetic forces that can be used for actuation
Implementation Method 2
induces eddy currents into the plate, leading to large repulsive electromagnetic forces
Implementation Method 3
a second actuator configured to change the state of the mechanical switch comprising a loaded spring system locked by a latch system
Data Source
Figure 1~3
Figure 4~5
Figure 6a~6b
AI summary
A switch system 500, 600, 700, comprising: a mechanical switch 210 for electrical currents, comprising a conductive state and a non conducive state; a first actuator 100 configured to change the state of the mechanical switch, wherein an actuation of the first actuator is based on a Thomson coil system; a second actuator 510 configured to change the state of the mechanical switch 210 comprising a loaded spring system locked by a latch system; wherein the first actuator 100 and the second actuator 510 each are configured to change the state of the mechanical switch 210 depending on a property of an electrical current passing the mechanical switch 210.