10 September 2020

Difference Between AC and DC Transmission Line

The most significant difference between the AC and the DC transmission line is that the AC transmission line uses three conductors for power transmission while in the DC transmission line requires two conductors. The other main difference between AC and DC transmission lines is explained in below to better understand this topic.


DC transmission line:

In the DC transmission line, the mercury arc rectifier converts the alternating current into the DC. The DC transmission line transmits bulk power over long distances. At the consumer ends the thyratron converts the DC into the AC.


AC transmission line:

The AC transmission line is used for transmitting the bulk of the power generation end to the consumer end. The power is generated in the generating station. The transmission line transmits the power generation to the consumer end. The power is transmitted from one end to another with the help of step up and step down transformer.

Difference between AC and DC transmission line:


  • The AC transmission line uses three conductors for long power transmission while in DC transmission line uses two conductors for power transmission.
  • The AC transmission lie transmits the alternating current over a long distance. While in DC transmission line is used for transmitting the DC over the long distance.
  • The high voltage drop occurs in the AC terminal line when their end terminals voltage is equal. The DC transmission line is free from inductance and hence no voltage drop occurs across the line.
  • The small conductor is used for AC power transmission as compared to the use of the DC transmission.
  • The dielectric loss occurs in the AC transmission line and not in the DC transmission line.
  • The AC trasmission line less expenasive as comapred to the DC trasmission line.
  • The AC transmission line has the difficulties of synchronization and stability whereas the DC transmission line is free from stability and synchronization.
  • The communication line interference is more in the Ac transmission line as compared to the DC transmission line.
  • At the same voltage, The DC transmission line has less stress as compared to the AC transmission line. Hence DC requires less insulation as compared to AC.
  • The AC transmission line has inductance and surges wheres the DC transmission line is free from inductance and surges. the inductance and the surges are nothing but the wave of the high voltage which occurs for a short duration. 
  • The AC transmission line requires the transformer to step up and step down the voltage, while in the DC transmission line the booster and chopper are used for step up and step down the voltage.
  • The Corona Effect is the phenomenon through which the ionization occurs across the conductor. And this ionization causes the losses in the conductor. The phenomenon of the corona effect occurs only in the AC transmission line and not in the DC transmission line.
  • The phenomenon of the skin effect occurs only in the AC transmission line. The skin effect causes the losses, and this can be reduced by decreasing the cross-section area of the conductor. The phenomenon of the skin effect is completely absent in the DC transmission line.

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