| Popis: |
Static VAR compensators (SVC) have been developed and introduced in the power industry and such equipment improves the quality of electrical transmission systems due to regulation of active and reactive power. Devices known as FACTS (Flexible AC Transmission Systems) operate at voltages of 35 kV, 110 kV and above. At such high voltage levels, the use of vacuum switch devices becomes competitive with semiconductor devices. The fact is that vacuum devices provide high voltage levels (100 kV and above), in comparison with semiconductor devices (6-7 kV). For use in high-voltage converters consecutive connection of many semiconductor devices with control circuitry is necessary. There are also other advantages of vacuum devices: high speed switching, stability of influence of electromagnetic interferences and heating. High-voltage breakdown in vacuum devices does not carry catastrophic character, unlike breakdown in semiconductor devices. |
