Vacuum circuit breakers and air circuit breakers are two common types of circuit breakers, and they differ significantly in terms of arc-extinguishing principles, structural characteristics, and applicable scenarios. The main differences between the two are as follows:
1. Arc Extinguishing Principle
Vacuum Circuit Breaker: Utilizes a high-vacuum environment (vacuum bulb) as the arc-extinguishing medium. When the contacts separate, the arc extinguishes rapidly in the vacuum environment due to the lack of a conductive medium. The contacts are specially designed so that a magnetic field is generated when current flows through them, causing the arc to move rapidly along the tangential direction and cool down, eventually extinguishing when the current crosses zero.
Air Circuit Breaker: Relies on air for arc extinguishing. An arc-extinguishing grid device elongates the arc, and air cooling extinguishes it. Compressed air is required to assist in the opening and closing actions during the arc extinguishing process.
2. Structure and Operation Method
VS1-12 Vacuum Circuit Breaker: Simple structure, no need for air reservoir, opening and closing of the circuit is controlled by an electro-pneumatic valve and an electromagnet. Small contact gap (e.g., only about 10mm for a 10kV circuit breaker), long mechanical life.
Air circuit breakers: These require a compressed air reservoir to store compressed air, and rely on compressed air for opening and closing. They have a complex structure, a high failure rate, and are greatly affected by ambient temperature and humidity.
3. Performance Characteristics
Vacuum Circuit Breaker: Short arcing time (approximately half a cycle), long electrical life (30-50 full-capacity breaking cycles, over 5000 rated current breaking cycles).
Suitable for frequent operation, low noise, small size, and light weight.
Fast dielectric recovery speed, suitable for breaking capacitive loads and near-zone faults.
Air Circuit Breaker: Strong breaking capacity, but lower arc extinguishing efficiency and susceptible to environmental corrosion.
Higher maintenance costs; requires regular inspection of the compressed air system.
4. Applicable Scenarios
Vacuum Circuit Breakers: Primarily used in high-voltage applications (e.g., 10kV and above) or situations requiring high arc extinguishing capabilities, such as power distribution networks, industrial and mining enterprises, and substations. Not suitable for DC circuits.
Air Circuit Breakers: Commonly found in low-voltage power distribution networks (e.g., household and industrial power distribution), suitable for general overload and short-circuit protection, but gradually being replaced by vacuum or sulfur hexafluoride circuit breakers.
5. Cost and Maintenance
Vacuum circuit breakers: High initial cost, but low failure rate and long maintenance cycle.
Air circuit breakers: Lower price, but frequent maintenance and shorter lifespan.
In summary
Vacuum circuit breakers have become the preferred choice for high-voltage and frequent operation scenarios due to their high arc-extinguishing efficiency, long lifespan, and compact design; while air circuit breakers, due to their simple structure and low cost, are still widely used in low-voltage fields, but are gradually being replaced by new technologies.
Shaanxi West Power Tongzhong Electrical Co., Ltd.
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Nanpo Village, Chencang Avenue Jintai District Baoji City, Shaanxi Province, China.
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