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In the power systems analysis field of electrical engineering, a per-unit system is the expression of system quantities as fractions of a defined base unit quantity. . Calculations are simplified because quantities expressed as per-unit do not change when they are referred from one side of a transformer to t
It aims to allow application software to exchange information about an electrical network. [1] It has been officially adopted by the International Electrotechnical Commission (IEC). The CIM is currently maintained as a UML model. [2] It defines a common vocabulary and basic ontology. CIM models the network itself using the 'wires model'.
The telegrapher's equations, like all other equations describing electrical phenomena, result from Maxwell's equations. In a more practical approach, one assumes that the conductors are composed of an infinite series of two-port elementary components, each representing an infinitesimally short segment of the transmission line:
In electrical engineering, three-phase electric power systems have at least three conductors carrying alternating voltages that are offset in time by one-third of the period. A three-phase system may be arranged in delta (∆) or star (Y) (also denoted as wye in some areas, as symbolically it is similar to the letter 'Y').
In electrical engineering, susceptance (B) is the imaginary part of admittance (Y = G + jB), where the real part is conductance (G). The reciprocal of admittance is impedance ( Z = R + jX ), where the imaginary part is reactance ( X ) and the real part is resistance ( R ).
A number of fundamental electrical laws and theorems apply to all electrical networks. These include: [3] Faraday's law of induction: Any change in the magnetic environment of a coil of wire will cause a voltage (emf) to be "induced" in the coil.
Continuous charge distribution. The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal n̂, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
The terms , [2] are also used, [4] as are the terms back EMF constant, [5] [6] or the generic electrical constant. [2] In contrast to K v {\displaystyle K_{\text{v}}} the value K e {\displaystyle K_{\text{e}}} is often expressed in SI units volt–seconds per radian (V⋅s/rad), thus it is an inverse measure of K v {\displaystyle K_{v}} . [ 7 ]