Advantages and Disadvantages of DC transmission

Advantages of DC transmission:

  1. It requires only two conductors.

  2. There is no problem of inductance, capacitance and phase displacement which is common in ac transmission.

  3. For the same load and sending end voltage, the voltage drop in dc transmission lines is less than that in ac transmission.

  4. As there is no skin effect on conductors, therefore entire cross-section of conductor is usefully utilized thereby affecting saving in material.

  5. For the same value of voltage insulating materials on dc lines experience less stress as compared to those on ac transmission lines.

  6. A dc line has less corona loss and reduced interference with communication circuits.

  7. There is no problem of system instability so common in ac transmission.

Disadvantages of DC transmission:

  1. Generation of power at high dc voltages is difficult due to commutation problems and cannot be usefully utilized at Consumer ends.

  2. Step up or step-down transformation of dc voltages is not possible in equipment like transformer.