August 22, 2012

What are the advantages of high voltage transmission and its limitations.

Advantages and Limitations of high voltage transmission line: 

The choice of transmission systems and rated voltages for a transmission line is made from HV AC (upto 220 kV) EHV AC (400 kV – 750 kV) UHVAC (above 760 kV AC) depending upon technical and economic consideration.

Advantages : 

  • High power transferability of AC lines P α V2. 
  • Line losses decrease with increase of transmission voltage and improvement of power factor for same power transfer. 
  • Bulk power transfer from large group of generating stations upto main transmission network. 


  • Higher voltage gives lesser current, lesser I2R losses.
  • Short circuit levels: In case of very long lines of above 500 km, intermediate switching sub-stations are necessary to install the shunt reactors for compensation. 
  • Right of way: In some cases of big cities, industrial localities, it is impossible to acquire right of way for EHV AC lines. 
  • Line insulation: The creep age distance (leakage distance) determined on the basis of required impulse with stand level. 
  • Corona: The critical value of voltage stress depends upon pressure, temperature, humidity, pollution level in air.


2 Comment(s):

  1. Reliability is also one the factor to be discussed for high voltage transmission


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