Vacuum Circuit Breaker VCB

Vacuum circuit breakers are considered a type of circuit breaker that uses vacuum between connected electrodes as the arc extinguishing medium. Vacuum circuit breakers are used in voltage ranges from 11kV to 33kV. During the operation of a vacuum circuit breaker, the contacts remain enclosed within a fully sealed vacuum chamber.

Because vacuum exists inside where the contacts are located, the contacts are separated in an environment where arcing is inherently suppressed. The most significant advantages of vacuum circuit breakers include minimal maintenance requirements, no gas emissions into the atmosphere, long service life, low noise, and reduced risk of fire hazards. They are suitable for indoor applications.

Features and Applications

1. The contact gap is small: for a 10 kV vacuum circuit breaker, the contact gap is only about 10 mm. This reduces the operating work required for the operating mechanism, shortens the mechanical travel distance, and thus extends its mechanical life.

2. The arcing time is short and independent of the magnitude of the switching current, typically only half a cycle.

3. After arc extinction, the dielectric recovery speed of the contact gap is fast, making it well-suited for breaking near-zone faults.

4. Due to minimal wear on the contacts during current interruption, their electrical life is long: full-capacity breaking can be achieved 30–50 times, and rated current breaking exceeds 5,000 times. With low noise, they are suitable for frequent operations.

5. Small in size and light in weight.

6. Suitable for breaking capacitive load currents.

Usage Environment

1. ‌Temperature Conditions‌: The operating temperature range for vacuum circuit breakers is typically -40℃ to +40℃. For outdoor products, the lower temperature limit is -40℃, while for indoor products in high-cold regions, the lower temperature limit is -25℃. Additionally, the storage temperature range is -40℃ to +85℃.

2. Humidity Conditions‌: In terms of relative humidity, the daily average should not exceed 95%, and the monthly average should not exceed 90%. In high-humidity environments, moisture protection measures must be taken to prevent internal condensation from affecting insulation performance.

3. ‌Air Pressure Conditions‌: The altitude should not exceed 1000 m to 2000 m. When used in high-altitude areas, the equipment must have excellent sealing performance to prevent external gas from entering the interior.

4. ‌Electromagnetic Interference‌: Wind and photovoltaic systems may contain electromagnetic interference sources such as lightning and frequency converters. Appropriate electromagnetic shielding and filtering measures are required to ensure stable equipment operation.

5. ‌Vibration and Shock‌: Vacuum circuit breakers need to have a certain level of vibration and shock resistance, especially for outdoor use, where natural factors such as wind and earthquakes must be considered.