Center Break Switch Auxiliary Contact Spring Mechanism
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Solution Overview
Problem
High-voltage switchgear contacts face increased wear and tear due to higher electrical and mechanical stresses at higher current ratings, making existing contact systems unsuitable for efficient bus transfer switching.
Innovation Solution
A center break switch with two moving contacts, where a finger contact and a fist contact engage and disengage in a specific sequence, utilizing a spherical contacting element and a compression spring to maintain contact pressure and handle the stresses, with the auxiliary finger and rectangular contacting element ensuring reliable bus transfer switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact systems (contact fingers and fist contact) are used in high-voltage switchgear, then the basic switching function is achieved, but the contacts experience excessive wear and tear due to high electrical and mechanical stresses at higher current ratings
Solution Approach 1:
The auxiliary contact is designed to engage before the main contact during closing operation, establishing a preliminary conductive path. This preliminary action allows current to transfer gradually and reduces the mechanical shock and electrical stress on the main contact, thereby reducing wear and tear while maintaining reliability
Solution Approach 2:
A spring mechanism is incorporated to provide cushioning force during contact engagement. The spring absorbs mechanical shock and maintains optimal contact pressure, protecting the contact surfaces from excessive stress and reducing wear during high-current switching operations
2Power
If contact fingers and fist contact are used for bus transfer switching, then the switching capability is provided, but the contacts cannot handle the electrical and mechanical stresses at high current ratings (2000 A or more)
Solution Approach 1:
The auxiliary contact engages first during closing to establish a preliminary current path before the main contact carries full load. This gradual current transfer reduces the instantaneous mechanical and electrical stress on the main contact, enabling the system to handle higher current ratings without exceeding contact strength limits
Solution Approach 2:
The contact system is segmented into auxiliary contact and main contact with distinct functions. The auxiliary contact handles the initial engagement and current transfer, while the main contact handles steady-state current conduction. This segmentation distributes the electrical and mechanical stresses across multiple contact elements, enabling higher overall current ratings
3Ease of operation
If the contact system engages and disengages simultaneously, then the switching operation is simple, but the contacts are exposed to higher electrical and mechanical stresses during bus transfer
Solution Approach 1:
The auxiliary contact is designed to engage before the main contact during closing and disengage after the main contact during opening. This sequential action, while adding a slight complexity to the mechanism, protects the contacts from excessive stress during bus transfer, thereby improving contact durability and reliability
Solution Approach 2:
The contact system employs dynamic engagement sequences where the auxiliary contact is actuated at different times relative to the main contact based on the switching direction. This dynamic timing optimization reduces stress exposure while maintaining operational simplicity through coordinated actuation mechanisms
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 solution provides improved contact reliability and reduced wear by ensuring the contacts are first to engage and last to disengage, maintaining contact pressure through the spring, thus enhancing the handling of high-voltage electrical and mechanical stresses.
Implementation Method 1
The spring can provides initial compression during switching and maintain contact pressure during engagement between the finger contact and the fist contact
Data Source
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AI summary
The invention relates to a center break switch having a contact system for electrical current conduction and bus transfer switching. The contact system comprises two moving contacts. One of the two moving contacts comprises a finger contact and the other moving contact comprises a fist contact. Each moving contact comprises a contact for bus transfer switching, wherein one of the two contacts comprises a spherical contacting element, and the other contact comprises a rectangular contacting element. The spherical contacting element and the rectangular contacting element engage during switching for the bus transfer, and stay in contact when the finger contact is engaged with the fist contact for electrical current conduction.