HVDC Bypass Switch Interrupting Chamber With Movable Blowing Nozzle
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Solution Overview
Problem
Current HVDC bypass switches are costly and large due to the need for multiple interrupting chambers, increased mechanical control for fast operation, and doubts about the long-term dielectric strength of materials in direct current environments, particularly with existing blowing nozzles.
Innovation Solution
A single interrupting chamber design with a movable pair of contacts and a tubular insulating gas nozzle that remains in a confinement position during opening to confine arcs and evacuate polluted gas, decoupling voltage withstand and current cutoff, using pneumatic thrust and a compression spring for nozzle retraction after current interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple interrupting chambers are used, then voltage withstand capability is improved, but device size and cost increase
Solution Approach 1:
The blowing nozzle is made movable rather than fixed, allowing it to change position dynamically. During normal operation, the nozzle extends into the insulating space to provide enhanced voltage withstand capability. During arc interruption, the nozzle retracts to avoid interference with the arc path. This dynamic positioning eliminates the need for multiple interrupting chambers while maintaining both voltage withstand capability and compact size.
2Reliability
If increased clearance of insulating space is used, then voltage withstand is improved, but operating speed must increase
Solution Approach 1:
The blowing nozzle dynamically adjusts the effective insulating space clearance. During voltage withstand phase, the nozzle extends to increase clearance and enhance insulation. During arc interruption, the nozzle retracts quickly, allowing the arc to be confined and extinguished without requiring the entire system to operate at extremely high speeds. The movable nozzle provides the necessary insulation enhancement without imposing stringent speed requirements on the overall switching mechanism.
3Reliability
If solid insulators are used in interrupting zone, then dielectric strength is improved, but radial and axial dimensions increase
Solution Approach 1:
The patent uses a movable blowing nozzle that can be positioned dynamically rather than employing fixed solid insulators. The nozzle delivers insulating gas directly to the arc zone, providing dielectric strength enhancement without requiring large radial or axial dimensions for solid insulator components. The pneumatic delivery system allows compact chamber design while maintaining high dielectric strength where needed.
4Reliability
If blowing nozzle remains in confinement position during opening, then arc confinement is improved, but current interruption time increases
Solution Approach 1:
The blowing nozzle is designed to move dynamically between confinement and retracted positions. During the arc interruption phase, the nozzle remains in the confinement position to effectively contain and extinguish the arc. Once interruption is achieved, the nozzle quickly transitions to the retracted position. This dynamic behavior provides effective arc confinement when needed while minimizing the time the nozzle occupies the insulating space, thus reducing current interruption time.
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 design reduces the size and cost of HVDC bypass switches while effectively confining arcs and ensuring complete current interruption, allowing for reliable operation in high-voltage direct current systems.
Implementation Method 1
an insulating gas blowing nozzle, of generally tubular shape, also movable in translation along the longitudinal axis
Implementation Method 2
using pneumatic thrust and a compression spring for nozzle retraction after current interruption
Implementation Method 3
using pneumatic thrust and a compression spring for nozzle retraction after current interruption
Data Source
Figure 1~3
Figure 2A~2B
Figure 2C
AI summary
The chamber (1) has a movable contact (3) and a tubular shaped arc blast isolating nozzle (5) extending along a longitudinal axis (XX'). The movable contact and the nozzle are moved independent from each other such that the nozzle is displaced to a withdrawal position at which the nozzle is removed from an insulating space in which the nozzle is maintained in a confinement position (C) by acceleration of insulating gas from the chamber while opening the contact.