Ueq

Ueq is a notation used in several technical fields to denote an equivalent quantity, most commonly an equivalent voltage in circuit analysis. There is no single universally accepted definition for Ueq, and its exact meaning depends on the context and the author.

In electrical engineering and circuit theory, Ueq often refers to the equivalent voltage source that represents a complex network when it is reduced to a simple two-terminal form. Such a reduction yields a single voltage source in series with an equivalent impedance, commonly written as Ueq in series with Z_eq (the Thevenin or Norton equivalent). The equivalent voltage can be found by analyzing the open-circuit voltage at the terminals or by applying superposition in networks with multiple sources. For DC circuits, Ueq may equal the algebraic sum of contributing voltages, taking into account their orientations; for AC circuits, Ueq represents the phasor voltage of the equivalent source, with Z_eq representing the corresponding impedance.

Outside electrical engineering, Ueq can appear in other domains with different meanings, but its interpretation remains field-specific and not standardized. In every usage, Ueq signals that a complex, possibly variable, quantity has been collapsed into a single representative value for the purposes of analysis or modeling.

Because the meaning of Ueq varies, readers should consult the surrounding notation or source material to determine the precise definition. Related concepts include Thevenin and Norton equivalents, superposition, and impedance simplification techniques.