Gas Insulated Substaton
1-INTRODUCTION:-
The increasing demand of electrical power in cities and industrial centres necessitates the installation of a compact and efficient distribution and transmission network. High voltage gas insulated switchgear (GIS) is ideal for such applications. The range of application of SF₆ Gas Insulated Switchgear extends from voltage ratings of 72.5 kV up to 800 kV with breaking currents of up to 63 kA, and in special cases up to 80 kA. Both small transformer substations and large load- centre substations can be designed with GIS technology. The distinctive advantages of SF₆ Gas Insulated Switchgear are: compact, low weight, high reliability, safety against touch contact, low maintenance and long life. Extensive in-plant preassembly and testing of large units and complete bays reduces assembly and commissioning time on the construction site. GIS equipment is usually of modular construction. All components such as bus bars, disconnectors, circuit-breakers, instrument transformers, cable terminations and joints are contained in earthed enclosures filled with sulphur hexafluoride gas (SF₆). Fig. 1 gas insulated substation Fig. parts of substation
2 -WHY DO WE NEED GIS (Gas Insulated Substation):-
Gas Insulated Substations are used where there is space for providing the substation is expensive in large cities and towns. In normal substation the clearances between the phase to phase and phase to ground is very large. Due to this, large space is required for the normal or Air Insulated Substation (AIS). But the dielectric strength of SF6 gas is higher compared to the air, the clearances required for phase to phase and phase to ground for all equipments are quite lower. Hence, the overall size of each equipment and the complete substation is reduced to about 10% of the conventional air insulated substation.
Extremely high dielectric properties of SF6 have long been recognized. Compressed SF6 has been used as an insulating medium as well
The increasing demand of electrical power in cities and industrial centres necessitates the installation of a compact and efficient distribution and transmission network. High voltage gas insulated switchgear (GIS) is ideal for such applications. The range of application of SF₆ Gas Insulated Switchgear extends from voltage ratings of 72.5 kV up to 800 kV with breaking currents of up to 63 kA, and in special cases up to 80 kA. Both small transformer substations and large load- centre substations can be designed with GIS technology. The distinctive advantages of SF₆ Gas Insulated Switchgear are: compact, low weight, high reliability, safety against touch contact, low maintenance and long life. Extensive in-plant preassembly and testing of large units and complete bays reduces assembly and commissioning time on the construction site. GIS equipment is usually of modular construction. All components such as bus bars, disconnectors, circuit-breakers, instrument transformers, cable terminations and joints are contained in earthed enclosures filled with sulphur hexafluoride gas (SF₆). Fig. 1 gas insulated substation Fig. parts of substation
2 -WHY DO WE NEED GIS (Gas Insulated Substation):-
Gas Insulated Substations are used where there is space for providing the substation is expensive in large cities and towns. In normal substation the clearances between the phase to phase and phase to ground is very large. Due to this, large space is required for the normal or Air Insulated Substation (AIS). But the dielectric strength of SF6 gas is higher compared to the air, the clearances required for phase to phase and phase to ground for all equipments are quite lower. Hence, the overall size of each equipment and the complete substation is reduced to about 10% of the conventional air insulated substation.
Extremely high dielectric properties of SF6 have long been recognized. Compressed SF6 has been used as an insulating medium as well