The vacuum - making process in a low voltage vacuum interrupter is a crucial aspect that determines its performance and reliability. As a supplier of low voltage vacuum interrupters, I have in - depth knowledge of this process and its underlying principles. In this blog, I will explore the key principles of the vacuum - making process in low voltage vacuum interrupters.
The Basics of Low Voltage Vacuum Interrupters
Low voltage vacuum interrupters are essential components in electrical systems, especially in low - voltage circuit breakers. They are designed to interrupt the flow of current in case of an electrical fault or when normal switching operations are required. The high - quality vacuum inside the interrupter plays a vital role in achieving efficient arc quenching and preventing re - ignition of the arc.
The Principle of Vacuum Creation
Initial Cleaning and Assembly
Before creating a vacuum, the components of the low voltage vacuum interrupter need to be thoroughly cleaned. This is because any impurities, such as dust, grease, or oxides on the surfaces of the contacts and the enclosure, can release gases during the vacuum - making process and affect the final vacuum quality. The cleaning process typically involves using solvents and ultrasonic cleaning techniques to remove these contaminants.
Once the components are clean, they are carefully assembled. The contacts, shields, and other internal parts are placed inside the enclosure, which is usually made of ceramic or glass. These materials have good insulating properties and can withstand the high - voltage and high - temperature conditions during operation.
Evacuation Process
The next step is the evacuation of the air from the assembled enclosure. This is achieved using a vacuum pump system. There are different types of vacuum pumps used in the process, such as rotary vane pumps and diffusion pumps.
Rotary vane pumps are often used as the first - stage pumps. They work by creating a partial vacuum by mechanically removing air from the enclosure. These pumps can typically achieve a vacuum level of around 10⁻² to 10⁻³ Torr. The working principle of a rotary vane pump involves a rotor with vanes that rotate inside a cylindrical chamber. As the rotor rotates, the vanes slide in and out of slots in the rotor, creating chambers of varying volumes. Air is drawn into the chamber through an inlet port and then expelled through an outlet port as the volume of the chamber decreases.
After the initial evacuation by the rotary vane pump, a diffusion pump is usually used to achieve a higher vacuum level. Diffusion pumps operate based on the principle of vapor jet pumping. A working fluid, such as oil, is heated to create a high - velocity vapor jet. The vapor jet entrains gas molecules from the enclosure and carries them towards the pump's exhaust. The gas molecules are then condensed and removed from the system. Diffusion pumps can achieve vacuum levels as low as 10⁻⁶ to 10⁻⁷ Torr.
Baking and Degassing
During the evacuation process, some gases may still be adsorbed on the surfaces of the components inside the enclosure. To remove these adsorbed gases, the interrupter is baked at an elevated temperature. Baking helps to release the gases from the surfaces, allowing them to be pumped out by the vacuum pumps.
The baking temperature and time depend on the materials used in the interrupter. For example, ceramic components may require a higher baking temperature compared to metal contacts. The baking process also helps to activate getters, which are materials that can chemically react with residual gases to further improve the vacuum quality.
Getter Activation
Getters are an important part of the vacuum - making process in low voltage vacuum interrupters. They are usually made of materials such as barium, titanium, or zirconium. Getters are placed inside the interrupter enclosure and are activated during the final stages of the vacuum - making process.
When the getter is heated, it undergoes a chemical reaction with residual gases, such as oxygen, nitrogen, and water vapor. The getter material forms stable compounds with these gases, effectively removing them from the vacuum environment. This helps to maintain a high - quality vacuum over the long - term operation of the interrupter.
Importance of Vacuum Quality
The quality of the vacuum inside the low voltage vacuum interrupter has a significant impact on its performance. A high - quality vacuum ensures efficient arc quenching. When the contacts in the interrupter separate, an arc is formed. In a vacuum environment, the arc is quickly extinguished because there are few gas molecules to sustain the arc. The low gas density in the vacuum also reduces the probability of re - ignition of the arc after it has been extinguished.
Moreover, a good vacuum helps to prevent oxidation and corrosion of the contacts. In a low - pressure vacuum environment, the amount of oxygen and moisture is extremely low, which protects the contacts from chemical reactions that could degrade their performance over time.
Related Products
If you are interested in other types of vacuum interrupters, we also offer High Voltage Vacuum Interrupter and Vacuum Interrupter for Outdoor Circuit Breaker. Our Molded Vacuum Interrupter is also a popular choice for many applications, providing reliable performance and easy installation.
Conclusion
The vacuum - making process in a low voltage vacuum interrupter is a complex and precise procedure that involves multiple steps, from component cleaning and assembly to evacuation, baking, and getter activation. Each step is crucial for achieving a high - quality vacuum that is essential for the efficient and reliable operation of the interrupter.
If you are in the market for low voltage vacuum interrupters or have any questions about our products, we encourage you to contact us for a procurement discussion. Our team of experts is ready to provide you with detailed information and support to meet your specific requirements.
References
- Blackburn, T. D. (2015). Protective Relaying: Principles and Applications. CRC Press.
- Greenwood, A. (1991). Electrical Transients in Power Systems. John Wiley & Sons.
- Stoll, R. (2008). High - Voltage Vacuum Interrupters: Theory, Design, and Application. Springer.