tasajännitteet

Tasajännitteet, or direct voltages, refer to a potential difference between two points that drives current predominantly in one direction. In a direct-voltage system, the current flow is unidirectional, and the voltage is typically described as constant in time. In practice, real DC sources may exhibit small variations or ripple, especially if they originate from rectified AC or from devices with switching regulation.

Key characteristics include polarity, stability, and the absence of a changing alternating component in an ideal case. The magnitude and sign of tasajännite are defined with respect to a reference point. DC voltage is commonly measured with instruments set to a DC range; the unit is the volt (V). Real-world DC sources may be rated by their nominal voltage and by their ability to regulate that voltage under varying load.

Common sources of tasajännitteet are batteries (alkaline, lithium, nickel-metal hydride, etc.), DC power supplies, and photovoltaic cells. Some devices and systems convert alternating current to direct current using rectifiers and regulators to achieve a stable DC output. DC is favored when a steady potential is required, such as in electronics, automotive applications, battery charging, and certain power transmission concepts like high-voltage direct current (HVDC).

Safety considerations emphasize that DC can be dangerous due to its ability to cause continuous arcing and sustained current flow, particularly at higher voltages or with large stored energy in capacitors. Proper insulation, isolation, and appropriate protective equipment are important when working with tasajännitteet.

See also: vaihtojännite (AC voltage) and power regulation.