Let us see the transmission of DC power from the AC power. The single line diagram of high voltage direct current transmission is given in Alternative current is generated and stepped up to high voltage through the sending end transformer. This high voltage alternating current is converted to the direct current by a mercury arc rectifier. The transmission of electric power is carried out at high DC voltage. At the receiving end, the DC voltage is converted into alternating current through the help of thyratrons. This alternating current is reduced to the low voltage through the receiving end transformer for distribution.
Advantages of DC transmission
i. Two conductors are sufficient for distribution of power supply
ii. There is no inductance and capacitance.
iii. No skin effect in DC transmission lines.
iv. The corona loss is lower as compared to AC system.
v. Voltage drop is very low.
Disadvantages of DC transmission
i. It is difficult to produce high voltage
ii. The voltage cannot be increased or decreased by using a transformer