Direct Current (DC)

The unidirectional flow of electric charge particles is called Direct current or DC. That is the electric current flows in a single direction. When a direct current is passed through a conductor the charge across the area of cross-section is uniform. Direct current is usually abbreviated as DC.

The value of the Direct Current is always constant with respect to time and the below figure shows its graphical representation. Hence in DC circuits the voltage and current are independent on time.

Direct Current (DC)

At the initial stages of development of electrical systems DC is used being used as means of transmission and distribution. Later with the adoption AC with its capability of easy transformation DC system is rarely used.

Sources of Direct Current:

Batteries: batteries are electrochemical energy conversion devices which produce Direct currents.

Solar cells: solar cells or photo voltaic cells convert light energy into electrical energy and they can only generate direct current.

DC Generators: Though DC generators generate DC but they do not generate pure DC instead they generate pulsating voltages. These have to be filtered with the help of filter circuits to get pure DC

Rectifiers: Rectifiers are the devices convert AC to DC

Applications:

Electronics: Most of the electronic devices like mobile phones, computers, radios, televisions, Audio/Video Players, LED lights, electronic watches and calculators etc. work on DC. As the supplies system is alternating current, these devices are powered with the help of rectifiers or run over batteries.

HVDC: For bulk power transmission of electric power over long distance High Voltage Direct Current (HVDC) transmission is used. DC has advantage of less losses and no skin effect.

Electric Vehicles: Electric Vehicles are battery powered vehicles which works on DC.

Rechargeable Batteries: Rechargeable batteries are energy storage devices which require DC input.