Vdc

Vdc, often written as V with a subscript DC, denotes direct current voltage—the voltage associated with direct current (DC) electrical systems. It is the potential difference expressed in volts that drives current in a circuit where the current does not alternate in direction, in contrast to Vac, the voltage of alternating current. In many datasheets and schematics, Vdc specifies either a supply rail voltage or the DC component of a waveform.

Measurement and interpretation: For a steady DC source, Vdc is constant over time. For a mixed or pulsed waveform, the DC component is the average value over time. In AC signals, Vrms and Vpeak relate to the AC portion, while the DC component is the mean value. When measuring with a multimeter in DC mode, the reading is the DC voltage.

Sources and applications: Common DC sources include batteries, solar cells, and regulated power supplies. DC voltages power most electronic circuits, LED drivers, and automotive electrical systems. In power transmission, high-voltage DC (HVDC) links carry large voltages over long distances to reduce losses. Equipment and components are often rated for Vdc, such as 5 V, 12 V, 400 Vdc, or higher for industrial drives.

Safety and standards: Handling high Vdc requires awareness of insulation and clearance distances; standards and safety guidelines define permissible voltages and measurement practices. See also direct current, DC bus, and related terms like Vrms and Vpeak.