What is Gas Circuit Breaker and Gas insulated sub station
What is Gas Circuit Breaker
A circuit breaker that uses sulfur hexafluoride gas for arc extinguishing and insulation is called a gas circuit breaker.
Over time the bulk oil circuit breaker has been changed to a low oil circuit breaker. Airblast circuit breakers come in to improve circuit breaker performance. The cost of the Air Blast Circuit Breaker is very high and because of its difficulty in repairing and repairing, it was thought that the circuit breaker should be so. What performance is similar to or better than Air Blast Circuit Breaker. And repairs are minimal and inexpensive. Working in this direction came into existence in the decade of gas circuit breaker 1960. In these circuit breakers, sulfur hexafluoride gas is used for arc extinguishing and insulation in circuit breakers. Nowadays only sulfur hexafluoride gas circuit breakers are used at 11 kV and above voltages.
Before the sf6 gas circuit breaker, air blast circuit breaker technology was the best technology of our time. So in the beginning, the same principle was used in the sf6 gas circuit breaker except for the difference that sf6 gas went to the lower side of the high pressure after the arc was extinguished. And then the gas was brought back to the high-pressure side via the compressor. So that the gas is available to extinguish the arc again. Thus, sf6 worked in a closed circuit. In those days high pressure was 12 bar and low pressure 3 bar.
Since sf6 gas was converted to liquid at 12 bar pressure and below zero Centigrade. Thus in areas with low temperatures, the sf6 gas circuit breaker was difficult to use. One solution was to have automatic electric heaters installed in the gas chamber so that the temperature was not less than.
Further research has shown that the circuit breaker performance is the same at 3 bar pressure. Which is 25 bar pressure of the air blast circuit? So nowadays sf6 gas circuit breakers use a puffer system instead of double pressure system. The gas pressure in this system is from 3 bar to 5 bar. And when the breaker is open, gas is compressed through a piston and is released only when the arc is extinguished. And after the arc is played again the gas pressure in the entire chamber becomes the same. No compressor is needed in the buffer system. Nowadays only one arc chamber is required to intercept a 6300 Amp current at 200 kV, which has sf6 gas pressure up to 2 bar. Any amount of current can be intercepted or turned off by placing more arc chambers in series.
Gas Insulated Sub Station
The major drawback of indoor substations is that they cannot be designed for high voltage ratings. While the major drawback of outdoor substations is that they are designed for high voltage but space is more spacious.
Gas-insulated substations are actually indoor substations, but they have all the features of outdoor and indoor substations, meaning they usually require less space than traditional substations. And they can be built up to high voltage ratings thanks to the many features that are being used all over the world at stations. These are most popular in the US, Russia, Europe, Japan and the Middle East. Stations are operating very successfully.
Gas-insulated substations are such substations. Metal enclosed in various devices such as bus bars, current transformers, potentials transformers, circuits, breakers, surge resistors and earth switches. The sulfur hexafluoride gas inside it is loaded at 3kg/cm3 pressure due to its excellent insulating properties. The gas loaded inside all components reduces as an insulator.
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