ACspenning

ACspenning, or alternating current voltage, refers to an electrical potential that changes polarity and magnitude over time. In most power systems it is sinusoidal, though non-sinusoidal waveforms can occur in systems with extensive power electronics or specific loads. The key characteristic is that the voltage varies cyclically rather than staying at a constant value.

An instantaneous voltage is described by v(t) = Vm sin(2πft), where Vm is the peak voltage and f is the frequency. For power calculations and heating effects, the root-mean-square (Vrms) value is used, with Vrms = Vm/√2 for a sinusoid. The frequency f is determined by the electrical grid: commonly 50 Hz in Europe and much of Asia, and 60 Hz in the Americas. Voltage levels vary by region and application.

Household supplies are typically given as approximately 230 V RMS (Europe) or 120 V RMS (North America) with corresponding sinusoidal waveforms. Three-phase networks commonly provide higher voltages such as 400 V line-to-line or 230 V line-to-neutral in many parts of the world; industrial settings may use even higher levels (for example 11 kV or 33 kV) before stepping down for distribution.

AC is generated by alternators in power stations and distributed through high-voltage transmission lines. Transformers adjust voltage levels for efficient transmission and safe local distribution. End-user equipment is designed for the local AC characteristics or includes power electronics to convert to DC or other forms.

Safety and measurement rely on proper insulation, grounding, and protective devices. Electrical codes specify permissible voltages, clearances, and practices to prevent shocks and arcs.

See also: alternating current, electrical grid, power distribution.