Circuit breakers used for extra high voltages (EHV), typically ranging from 345 kV and above, are designed to handle the immense electrical stresses associated with these voltage levels. They need to reliably interrupt high levels of current and withstand the resulting arc and thermal stresses. Extra high voltage circuit breakers are often large, complex devices that use advanced technologies such as SF6 (sulfur hexafluoride) gas or vacuum interrupters to ensure effective interruption of faults and maintenance of system reliability at these critical voltage levels.
For high voltage and low current applications, such as in distribution networks or certain industrial settings, vacuum circuit breakers are commonly used. Vacuum circuit breakers offer excellent performance in terms of fast interruption times, minimal maintenance requirements, and suitability for medium to high voltage applications where current levels are relatively low compared to transmission systems. They provide reliable operation and can handle frequent switching operations without degradation.
A circuit breaker used for 220 kV applications typically falls under the category of high voltage circuit breakers. These are specifically designed to interrupt fault currents and manage the electrical stresses associated with 220 kV transmission systems. Common types used at this voltage level include SF6 circuit breakers, which use SF6 gas for arc quenching, or vacuum circuit breakers, which use a vacuum as the interrupting medium. These circuit breakers are critical for ensuring grid reliability and protecting equipment in high voltage transmission networks.
High voltage circuit breakers can be classified into various categories based on the interrupting medium, operating mechanism, and application. Common classifications include air blast circuit breakers, oil circuit breakers, SF6 circuit breakers, vacuum circuit breakers, and hybrid circuit breakers. Each type offers specific advantages depending on factors such as voltage level, current magnitude, switching frequency, and environmental considerations. The choice of circuit breaker type is crucial to ensure effective fault interruption, minimal maintenance, and long-term reliability of the electrical network.
Circuit breakers commonly used for 11 kV applications, which are typically found in distribution networks and industrial installations, include vacuum circuit breakers and SF6 circuit breakers. Vacuum circuit breakers are preferred for their compact size, reliable performance, and ability to handle moderate fault currents at medium voltage levels. SF6 circuit breakers are also used in some applications due to their high dielectric strength and ability to extinguish arcs quickly. Both types are designed to ensure safe and reliable operation of electrical distribution systems at 11 kV, protecting equipment and maintaining continuity of service.