Dual-Conductor Thomson Coil for Faster Hybrid Interrupter Opening
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Solution Overview
Problem
Existing Thomson coil actuators in hybrid circuit interrupters are limited in their ability to open mechanical separable contacts at high speeds, leading to increased let-through current due to the time elapsed between fault detection and contact separation.
Innovation Solution
A dual conductor Thomson coil actuator is designed with two nested conductors, each excited by a separate capacitor bank, allowing for faster magnetic repulsion and contact separation using the same total system energy as single conductor actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single conductor Thomson coil actuator is used, then the device complexity is lower, but the contact opening speed is insufficient leading to increased let-through current
Solution Approach 1:
The single conductor coil is segmented into two nested conductors (first conductor and second conductor) that are wound alternately. Each conductor is excited by a separate capacitor bank, allowing independent current control. This segmentation enables the generation of stronger aggregate magnetic force while maintaining a manageable structural complexity through the nested alternating winding pattern.
Solution Approach 2:
The first conductor and second conductor are nested within each other in an alternating pattern, with each conductor forming nested turns around the other. This nested configuration maximizes the magnetic field interaction and aggregate force generation within a compact space, achieving faster contact opening without proportionally increasing the actuator's external dimensions.
2Power
If the capacitor bank capacitance is increased to provide more energy, then the initial pulse current increases improving contact opening speed, but the device complexity and energy management complexity increase
Solution Approach 1:
The total capacitance required for high power delivery is segmented into two separate capacitor banks, each with half the capacitance of a single large bank. This segmentation allows for more manageable energy storage components while achieving the same total energy delivery capability, reducing individual component stress and simplifying the overall system architecture.
Solution Approach 2:
The system changes the electrical parameters by distributing the total capacitance across two separate banks, each operating at the same voltage but with half the capacitance. This parameter change enables the same total energy delivery (E=1/2CV²) while improving current delivery characteristics and reducing the complexity of any single capacitor bank.
3Loss of time
If the time between fault detection and contact separation is reduced, then the let-through current is minimized, but the actuator must operate at higher speeds requiring more energy
Solution Approach 1:
The capacitor banks are pre-charged to the required voltage before fault detection occurs. When a fault is detected, the pre-charged capacitors immediately discharge through the conductors, providing the high initial pulse current needed for rapid contact opening without requiring additional energy conversion time. This preliminary energy storage eliminates delays in energy delivery.
Solution Approach 2:
The energy delivery system is segmented into two independent capacitor-conductor pairs that can discharge simultaneously. This segmentation creates two parallel energy delivery paths that combine to produce a stronger aggregate magnetic force more quickly than a single path could achieve, reducing the time required for contact separation while distributing the energy management load.
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 dual conductor Thomson coil actuator achieves faster contact opening, reducing let-through current and minimizing arcing by increasing the initial pulse of current and magnetic force, thereby enhancing the speed of contact separation.
Implementation Method 1
The first conductor and the second conductor are nested such that the first number of turns forms alternating turns of the coil relative to the second number of turns. The first power source and the second power source are configured to simultaneously supply a first time-varying current signal and a second time-varying current signal, respectively, to the first conductor and the second conductor. The actuator is structured to cause the coil to repel the conductive plate when the first and second time-varying current signals are supplied to the first and second conductors.
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
A dual conductor Thomson coil actuator for use in opening the separable contacts of a circuit interrupter comprises two nested conductors wound to form a single coil, rather than the traditional design comprising one single conductor wound to form a coil of the same size. Each of the two conductors can be excited by half the capacitance that would be used to excite the traditional single conductor coil, using the same voltage as the single conductor coil. When the same total capacitor-stored energy that would be used to excite the single conductor coil is instead used to excite the dual conductor coil, the initial pulse of aggregate current through the dual conductor coil is greater than the initial pulse of current through the single conductor coil, resulting in a faster initial opening distance of the separable contacts during an opening stroke.