directvoltage

Direct voltage, commonly called direct current voltage or DC voltage, is a voltage whose magnitude remains essentially constant in time and whose current flows predominantly in one direction. In ideal terms, the instantaneous voltage v(t) equals a fixed value V. Real DC may show small ripple or drift, but the direction of current does not reverse.

DC is contrasted with alternating voltage (AC), where voltage varies cyclically and the direction of current periodically reverses. DC is widely used in electronics, power supplies, and propulsion systems, where stable voltage is required for proper operation of components and circuits.

Common sources include chemical cells and batteries (such as alkaline, lithium-ion, and lead-acid), DC power supplies (linear and switching regulators), and renewable sources like solar photovoltaic cells, which produce DC that is then converted for use. High-voltage direct current (HVDC) transmission uses converters to move power over long distances with potentially lower losses and controlled power flow.

Voltage and polarity are measured with a voltmeter or multimeter in DC mode. Key quantities include the voltage value V and the current I, with electrical power given by P = V × I. Sign convention follows the chosen reference direction of the circuit, with positive and negative terminals indicating relative potential.

Applications span electronics (logic circuits, batteries, sensors, and communication equipment), DC motors and actuators, and processes such as electroplating or electrolysis. Within devices, DC links and distributions are common, and in broader power systems DC is used in HVDC transmission and in many data-center and vehicle architectures, where efficient control of power flow is advantageous.

Safety considerations include the potential for sustained electrical shock and the ability of DC circuitry to store energy in capacitors, requiring proper insulation, disconnection procedures, and equipment rated for the voltage level involved.