Kokonaisnäennäisteho

Kokonaisnäennäisteho, often abbreviated as S, is a concept in electrical engineering that describes the total power delivered to an AC circuit. It is the vector sum of real power (P) and reactive power (Q). In simpler terms, it represents the apparent magnitude of power flowing in a circuit, regardless of whether it is doing useful work or being stored and released by reactive components.

The unit of measurement for apparent power is the volt-ampere (VA). It is calculated by multiplying the RMS voltage (V) across the circuit by the RMS current (I) flowing through it: S = V * I. Apparent power is a crucial parameter because it dictates the capacity of electrical equipment, such as transformers, generators, and conductors. These components must be rated to handle the apparent power, not just the real power, to avoid overheating and failure.

Real power, measured in watts (W), is the power that performs actual work, such as powering a motor or lighting a bulb. Reactive power, measured in volt-amperes reactive (VAR), is the power that oscillates between the source and reactive components like inductors and capacitors. It is necessary for the operation of many electrical devices but does not contribute to useful work. The relationship between these three types of power is often visualized using a power triangle, where S is the hypotenuse, P is the adjacent side, and Q is the opposite side. The power factor (cos φ) is the ratio of real power to apparent power (P/S), indicating how effectively the apparent power is being utilized.