KnotenSpannung

Knotenspannung, in English typically called node voltage, is the electric potential at a circuit node relative to a reference point, usually the ground. It is the central quantity in the nodal analysis method used for solving linear circuits. By assigning a voltage variable to each nonreference node, engineers form a set of algebraic equations that describe how currents flow through the circuit.

In nodal analysis, Kirchhoff’s current law is applied at each nonreference node: the sum of currents leaving or entering the node must balance. Currents along a branch between node i and node j are expressed as (V_i − V_j) / R_ij for resistive elements, with similar expressions for impedances in AC analysis. Current sources are incorporated directly into the equations as known contributions. If a voltage source lies between two nonreference nodes, a supernode is formed, and additional constraints from the voltage source are used to solve the system. If the voltage source is tied to the reference node, the node voltage is fixed by the source value.

The result is a linear system in the unknown node voltages, which can be solved to obtain all Knotenspannungen. Once these voltages are known, branch currents, power, and the overall behavior of the circuit can be determined. Node-voltage methods are widely taught and implemented in circuit simulators such as SPICE, and they offer advantages for circuits with many sources or where node variables are of particular interest.