Vacuum circuit breakers (VCB) interrupt current to avoid excess current that could be induced by an overload. They can also handle severe recovery transients that are often caused by short-line faults. These devices are known for their reliability, maintenance-free operations and eco-friendly properties. They are well-aligned with Japan’s stringent standards for renewable energy integration.

Vacuum circuit breakers (VCB) use a vacuum as an arc quenching medium. This is the primary difference between them and other types of circuit breakers. They are a perfect choice for medium voltage switchgear applications, especially those in the range of 11 to 33 kV. Discover the best value for used circuit breakers – click here or visit our official marketplace for more details.

VCBs are very simple to construct. Their outer envelope is made of glass, which facilitates external inspection after operation. If the glass changes from its silvery mirror appearance to a milky one, it indicates that the breaker has lost its vacuum. The arc interrupting mechanism is located inside an arc shield, and the contact space between the fixed and moving contacts is kept at about 10-6 torr during sealing. The movable contacts can move about 5 to 10 mm depending on the operating voltage. When the contacts separate, an arc is ignited by ionization of metal vapors from the current-carrying contacts. However, it is quickly extinguished as the arc is separated in a high vacuum environment. This makes VCBs suitable for AC current interruption applications, including switching power supplies and managing traction current.

Vacuum circuit breakers (VCBs) are regarded as one of the most reliable current interruption technologies. They require minimal maintenance compared to other circuit breaker technology and are primarily used for medium voltage switchgear. They are also available in metal-clad or porcelain encasements. The VCB mechanism is comprised of two contacts called fixed and movable contact. An arc is created between these contacts when an electrical fault occurs, and the movable contact is moved away from the fixed contact in a vacuum, which interrupts the flow of electricity. The arc in a VCB is short and has low energy, which means that the arc can be quickly extinguished, and there is little or no contact erosion. In addition, a VCB does not use harmful chemicals like SF6 gas and is more environmentally friendly than other types of circuit breakers. It is also more efficient, less bulky, and less expensive than other types of breakers. Its service life is significantly longer than other breakers and requires no regular maintenance.

Vacuum circuit breakers offer a higher short-circuit interrupting capacity than other breaker types. This is because their arc interruption mechanism relies on ionisation of metallic vapours that occur when the current-carrying contacts separate. These metallic ions and electrons quickly condense on the surfaces of the circuit breaker’s current-carrying contacts, thereby restoring dielectric strength. In addition to their high arc interruption capacity, vacuum circuit breakers also have the advantage of superior insulation. They offer several times more insulating strength than air and SF6 at high pressures.