01
- The Importance of Vacuum Interrupters
As a core component of switchgear, the performance of vacuum interrupters directly impacts the stability and safety of power systems. In today's rapidly evolving power technology, technological innovation and advancements in vacuum interrupters have become a focus of industry attention.
- Definition and Working Principle of Vacuum Interrupters
A vacuum interrupter, also known as a vacuum switch tube or vacuum bulb, is a core component of vacuum switches. It cleverly utilizes a pair of electrodes (contacts) and other precision components sealed in a vacuum environment, leveraging the insulating and arc-extinguishing properties of vacuum to close and open circuits. After power is disconnected, the device rapidly extinguishes the arc and effectively suppresses current flow.
- Classification of Vacuum Interrupters
Vacuum interrupters are categorized by their casing material and intended use, including glass and ceramic. Depending on their intended use, they can be used in various switchgear applications, such as circuit breakers and load switches. For example, TD-40.5/2500-31.5 designates a vacuum interrupter for circuit breakers with a ceramic housing, while BD-12/3150-40 designates a vacuum interrupter for circuit breakers with a glass housing.
- Basic Components of a Vacuum Interrupter
The basic components of a vacuum interrupter include an insulating housing, a bellows, a shielding tube, and a contact system. These components work together to ensure relia
ble current interruption. Working together in a high vacuum environment, these systems provide the interrupter with excellent electrical performance and mechanical durability.
02
Contact Structure and Magnetic Field Effects
- [Contact Structure Types]
Contact structures used to interrupt current vary, including transverse field contacts and longitudinal field contacts. These structures determine the interrupting capacity of the arc extinguishing chamber. Common structures include transverse field contacts, such as spiral groove transverse field contacts, cup-shaped transverse field contacts, and swastika-shaped transverse field contacts, and longitudinal field contacts, such as open-slot longitudinal field contacts, coil-shaped longitudinal field contacts, and horseshoe-shaped longitudinal field contacts.
- [Effects of Transverse and Longitudinal Field Contacts]
Various types of field contacts provide different effects during arc extinguishing, helping to improve the interrupting capacity of the arc extinguishing chamber. Transverse field contacts generate a magnetic field perpendicular to the electrode axis, while longitudinal field contacts generate a magnetic field aligned with the electrode axis. The longitudinal field helps improve the interrupting capacity of the switch and effectively reduces arc spot concentration on the contacts.
03
Vacuum Arc Principles and Influencing Factors
- [Conditions for Formation and Extinction of Vacuum Arcs]
A vacuum arc forms under specific conditions and extinguishes when the arc current decreases. Factors influencing this include electrode material and geometry. In a vacuum environment, when the voltage reaches a certain level, discharge occurs, ultimately forming a vacuum arc. When the current crosses zero, the arc extinguishes, and the high vacuum insulation between the contacts is restored.
04
Mechanical Characteristics and Performance Impact
- [Opening Distance and Contact Pressure]
Opening distance and contact pressure affect the electrical performance of the vacuum interrupter and the contact quality. The opening distance is affected by the rated voltage and withstand voltage of the vacuum interrupter, while contact pressure is crucial for ensuring good contact. In the absence of external forces, the self-closing force plus the preload ensures stable contact between the moving and stationary contacts.
- [Contact Travel and Time-Travel Characteristic Curve]
Contact travel affects contact pressure, while the time-travel curve describes the mechanical behavior of the circuit breaker. Contact travel is typically set at 20% to 40% of the opening distance to ensure reliable contact even when the contacts wear out or burn out. The time-travel characteristic curve provides detailed information on the closing and opening processes and is crucial for optimizing the mechanical characteristics of the circuit breaker.
