DCstrømmen

DCstrømmen, or direct current, is an electric current that flows in a single direction with a constant polarity. Unlike alternating current (AC), whose direction and magnitude vary cyclically, DC is characterized by a steady voltage or current over time. It is described by Ohm's law and is fundamental to many electrical and electronic systems.

DC can originate from chemical sources such as batteries and fuel cells, from DC generators, or from rectified AC using power electronics. It can be stored in batteries and capacitors and is often regulated by converters to provide stable output for electronics, vehicles, and industrial equipment.

Common applications include portable and handheld electronics, automotive powertrains with DC motors, data centers, and telecom equipment. Solar photovoltaic panels generate DC, which is typically converted to AC for the grid, or used directly in DC bus architectures. DC distribution can reduce complexity in certain installations.

Transmission using direct current, through high-voltage direct current (HVDC) systems, enables efficient long-distance and submarine power links and the interconnection of asynchronous grids. HVDC systems minimize certain losses and avoid reactive power issues, though they require dedicated converter infrastructure and control systems.

Historically, DC was central to early electrical distribution and equipment. The development of AC power systems in the late 19th and early 20th centuries led to the War of Currents, but modern HVDC and advances in power electronics have renewed interest in direct current for specific applications and grids worldwide.