Gas Insulated Substation: Types of Substation Switchgears

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  • Topic: Transformer, Electrical substation, Current transformer
  • Pages : 17 (3350 words )
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  • Published : April 19, 2013
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GIS – Gas Insulated Substation Why GIS Types of Substation Switchgears [AIS/HIS/GIS] Space Reduction Analysis with AIS/HIS/GIS Specifications for GIS & AIS 400 kV / 220 kV GIS 400 kV side GIS Single Line Diagram & Components of GIS 220 kV side GIS Visual Comparison Between AIS & GIS Components Techno - Economic Comparison Between AIS & GIS Advancement in GIS Life Cycle Cost Analysis – [AIS/HIS/GIS] World Scenario -GIS 2

Gas Insulated Substations (GIS) is a compact, multicomponent assembly enclosed in a ground metallic housing in which the primary insulating medium is compressed Sulphur hexafluoride (SF6) gas. SF6 acts as an insulation between live parts & the earthed metal closure.

The introduction of SF6 gas has revolutionized not only the technology of circuit breakers but also the layout of substations. The dielectric strength of SF6 gas at atmospheric pressure is approximately three times that of air. It is incombustible, non toxic, colorless and chemically inert. It has arc-quenching properties 3 to 4 times better than air at equal pressure. Space requirement is only 10 to 25 percent of what is required is a conventional substation.

GIS has small ground space requirements. Gas insulated Substations have easy maintenance( nearly zero Maintenance Less field erection time & less erection cost. For underground powerhouse of Hydro electric power project where space constraint is a major issue. For Fast Growing Major Cities where land availability is costlier. Non-Flammability & Non-Explosive , Oil-free & Less Pollution


Surge Arrestor

Bus Post Insulator

Current Transformer

Capacitor Voltage Transformer


Live Tank-Circuit Breaker

Dead Tank- CB


Surge Arrestor

Bus Post Insulator

Capacitor Voltage Transformer



The weight and size of the GIS equipment do not change appreciably with the voltage class as the bulk of the current – carrying components and enclosures have identical dimensions for similar thermal and short time current. The additional insulation required for the next voltage class is achieved by increased gas density. Owing to these flexibilities, a few manufacturers offer the same equipment for two voltage classes (like 170/145 kV). Even when the GIS equipment is designed for an individual voltage class, the dimensions and weights of the equipment differ marginally. Table shows the dimensions, weight and floor loading for three voltage classes of GIS. Rated voltage Bay width, m Bay Depth, m Bay height, m Floor area, sq.m Volume, m3 Weight, kg Floor loading, kg/sq.m kg/sq.m 1.5 3.3 3.2 4.95 15.84 3800 765 145 kV 170 kV 2.0 3.35 3.4 6.7 22.78 5000 750 245 kV 2.0 3.4 3.4 6.8 23.12 5700 840 13

132 Kv Clearances

220 Kv

400 Kv

765 Kv

Clearance Diff in Clearance Clearance Diff in Clearance Clearance Diff in Clearance for 132 Kv with Next for 220 Kv with Next for 400 Kv with Next Voltage class Voltage Class Voltage class 1.22 m 1.07 m 3.50 m 4.6 m 0.84 m 0.71 m 0.78 m 0.9 m 2.06 m 1.78 m 4.28 m 5.5 m 1.94 m 1.72 m 2.22 m 2.5 m 4.0 m 3.5 m 6.5 m 8.0 m 3.6 m 1.4 m 3.8 7.6 m 4.9 m 10.3m

Mini.Clearance B/W Ph – Ph Mini.Clearance B/W Ph - Ear Sectional Clearance Ground Clearance

Earth Clearance: this is the clearance between live parts and earthed structures, walls, screens and ground. Phase Clearance: this is the clearance between live parts of different phases. Section Clearance: this is the clearance between live parts and the terminals of a work section. The limits of this work section, or maintenance zone, may be the ground or a platform from which the man works. 14

Minimum Clearance for Different Voltage Level [GIS]
145 Kv (132 Kv) 245 Kv (220 Kv) 420 Kv 800 Kv (765 Kv)

Clearance Diff in Clearance Clearance Diff in Clearance Clearance Diff in Clearance for 132 Kv with Next for 220 Kv with Next for 420 Kv with Next Voltage Voltage class Voltage class class Centre-tocentre distance of phases Right-of way width...
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