20 October 2018

Types of Conductor

 Solid conductors

  • The cross – section of the solid conductors are small because it is very difficult to handle it due to higher weight. It may break at the some point due to wind pressure in long span. ( Span is defined as the distance between two towers ).

Stranded conductors

  • The stranded conductors are used in the transmission line.
  • Number of conductors in the stranded conductor
        N = 3n ( n + 1 ) + 1
        Where n = Number of layers
                  n = 0,   N = 1
                  n = 1,   N = 7
                  n = 2,   N = 19
                  n = 3,   N = 37
  • Diameter of conductor D = ( 2n + 1 ) d
                 n = 0,   D = d
                 n = 1,   D = 3d
                 n = 2,   D = 5d
                 n = 3,   D = 7d
  • The stranded conductor has greater flexibility as compared to solid conductors.

Hollow conductors

  • The diameter of hollow conductor is large as compared to solid conductors for same current capacity. 
  • The corona loss is eliminated due to large diameter of conductor. 
  • The skin effect of hollow conductor is less as compared to stranded conductor.
  • The inductance of the hollow conductor is less as compared to solid conductor.
  • As the diameter of conductor increases, it exposes higher weight due to wind pressure and ice accumulated on the conductor surface.

Bundle conductors

  • It is defined as the two or more than two conductors per phase. 
  • They are used for transmitting power for long distances. The sub conductors are separated by equal distance.

Advantages

  • Low corona loss due to large cross section of area
  • Low inductance per phase due to higher GMR ( Geometric Mean Radius )which reduces net reactance of the conductor.
  • The power transmission capacity increases as the reactance of the line decreases.
P = VSVR / X
  • Lower voltage regulation due to low inductive reactance
  • Reduced radio interference with communication lines
  • Improved stability

Disadvantages

  • Charging kVA increases
  • Size of tower increases due to large space between conductors
  • Wind and ice loading increases due to large diameter of conductor
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