Advantages Gas ( Nitrogen ) Filled Cable over solid cable

 Gas Pressure Cables

• The external pressure cable is designed by Hochstadter, Vogel and Bowden. 
• This cable is triangular shaped instead of circular shaped and thickness of lead sheath is about 75% of that of solid cable. 
• The triangular section reduces weight of cable and gives low thermal resistance. 
• The thermal resistance of cable reduces because of no bedding and serving in the cable. 
• The core of cable may be over section / circular section but generally it is designed for over section which improved copper surface factor.

• The cable is laid in gas tight metal pipe and this pipe is filled with nitrogen gas at a pressure of 12 to 15 atmosphere pressure. 
• This nitrogen gas at high pressure compresses the cable radially from outside therefore it closes any voids between the layers of paper insulation. 
• The metal pipe is coated with paint in order to reduce corrosion over it.  

Advantages of Gas pressure cable

• Operate at higher voltage as compared to normal cable
• It can carry more current
• The nitrogen gas helps in quenching any flame
• Steel pipe provides mechanical protection to the cable

Disadvantages

• High cost

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