Vacuum Valve Coil Electrode Design for Arc Diffusion
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Solution Overview
Problem
Vacuum interrupters face challenges in enhancing interruption capability and withstanding high voltage simultaneously, requiring complex and costly manufacturing processes for coil electrodes, which often lead to localized overheating and weak points in high-voltage endurance.
Innovation Solution
The design includes coil electrodes with varying groove widths on the contact surfaces to control current distribution and magnetic field strength, preventing eddy currents and ensuring uniform arc diffusion across the contact surfaces, thus enhancing both interruption capability and high-voltage endurance without complex manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coil portions are made equal in length, then the manufacturing is simplified, but the arc intensifies in a narrow area causing local overheating
Solution Approach 1:
The coil portions are designed with different lengths tailored to specific locations around the contact periphery. This non-uniform configuration ensures that each coil portion contributes appropriately to arc diffusion in its local region, preventing concentration of arc energy in any single narrow area and thus avoiding local overheating.
2Ease of manufacture
If a single coil electrode design is used, then the manufacturing cost is reduced, but the arc diffusion is non-uniform across the contact surface
Solution Approach 1:
The coil electrode is segmented into multiple independent coil portions with different lengths, each positioned at specific locations around the contact. This segmentation allows each portion to be optimized for its local arc diffusion requirements, achieving uniform overall arc diffusion across the entire contact surface while maintaining a relatively simple manufacturing approach.
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 a cost-effective, simple design that achieves homogeneous arc diffusion and robust high-voltage capability, reducing the risk of overheating and maintaining the integrity of the vacuum interrupter under high voltage conditions.
Implementation Method 1
coil electrodes provided to opposing end portions of the respective electrode bars... having an arm portion in the axial direction at one end of a coil and a protruding portion connected to the contacts at the other end so as to generate an axial magnetic field
Implementation Method 2
an electromagnetic force is generated. The electromagnetic force drives the arc in a direction in which the electromagnetic force acts and thereby moves the arc from the ignition position
Implementation Method 3
an eddy current is induced at the disc-shaped contact and there is a problem that a field generated by the eddy current weakens the axial magnetic field by the coil electrode
Data Source
AI summary
A fixed electrode 10 and a movable electrode have coil electrodes formed of plural coil portions installed at both contacts and on a rear surface side in a divided manner in a circumferential direction along peripheries of the contacts such that a longitudinal field is generated in a direction in which the fixed contact and the movable contact come close to and move apart from each other. Protruding portions joined to the contacts are provided to tip ends of the respective coil portions to form joint portions to the respective contacts. A current to be flowed is controlled by changing resistance values between the contacts and the coil electrodes for each joint portion.