Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

direct axis magnetizing (armature) reactance
a reactance that represents all the inductive effects of the d-axis stator current of a synchronous machine, except for that due to the stator winding leakage reactance. In Park's d-axis equivalent circuit of the synchronous machine, this reactance is the only element through which both the stator and rotor currents flow. Its value may be determined by subtracting the stator winding leakage reactance from the steady-state value of the d-axis operational impedance or from the geometric and material data of the machine.
a magnet that employs an electric current in a coil to produce a magnetic field.
electromagnetic compatibility (EMC)
the ability of a system or equipment to operate within design tolerances in its intended environment, with adjacent systems and equipment, and with itself, so that the effect of any electromagnetic disturbances produced by the systems or equipment is reduced.
electromagnetic energy
energy contained in electromagnetic fields and associated polarizable and magnetizable media.
electromagnetic environmental effects
encompasses all electromagnetic disciplines, including electromagnetic compatibility (EMC); electromagnetic interference (EMI); electromagnetic vulnerability (EMV); electromagnetic pulse (EMP); radiation hazard (RADHAZ) (hazard of electromagnetic radiation to personnel, ordnance, and fuels (HERP, HERO, HERF)); lightning, p-static; electrostatic discharge (ESD), and emission control (EMCON).
electromagnetic interference (EMI)
(1) any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics/electrical equipment. It can be induced intentionally, as in some forms of electronic warfare, or unintentionally, as a result of a spurious emissions and responses, intermodulation products, and the like. Additionally, EMI may be caused by atmospheric phenomena, such as lightning and precipitation static and non-telecommunication equipment, such as vehicles and industry machinery.

(2) unwanted high-frequency electrical signals, also known as radio frequency interference (RFI), which can be generated by
power electronic circuits switching at high frequencies. The signals can be transmitted by conduction along cables (450 kHz to 30 MHz) or by radiation (30 MHz to 40 GHz) and can interfere with control or other electronic equipment.
electromagnetic interference filter
a filter used to reduce or eliminate the electromagnetic interference (EMI) generated by the harmonic current injected back onto the input power bus by switching circuits. The harmonic current is caused by the switch action that generates switch frequency ripple, voltage and current spikes, and high-frequency ringing. Generally called an EMI filter.
electromagnetic pulse (EMP)
a large impulsive-type electromagnetic wave generated by nuclear or chemical explosions.
electromagnetic radiation
an electromagnetic wave created by the acceleration or deceleration of charge.
electromagnetic smart materials
materials such as shielding materials, radar-absorbing materials (RAMs), and electromagnetic surface materials, in all of which some electromagnetic properties can be adaptively controlled by means of an external stimulus dictated by the sensed electromagnetic response.
electromagnetic spectrum
the frequency and wavelength of electromagnetic radiation. We have the following classification reported in the figure, while the microwave frequency band designations is reported in the table.
electromagnetic susceptibility
a device's failure to perform appropriately if there is an electromagnetic disturbance.
electromagnetic torque
the torque produced in a machine by the interaction of the magnetic fields and/or by the varying reluctance principle where the field attempts to maximize its intensity in a machine during electromechanical energy conversion.
electromagnetic vulnerability (EMV)
the inability of a device, equipment, or system to perform without degradation when
subjected to electromagnetic environment of a specified power level and frequency range.
electromagnetic wave
wave in which the electric and magnetic variables are solutions of the Maxwell-Heaviside equations.
electromagnetic wave propagation
the phenomenon of electromagnetic energy propagating in the form of waves of the coupled
electric and magnetic field intensity vectors.
electromagnetically induced transparency
a technique to render optically dense media transparent by using a long-lived quantum Electromagnetic spectrum.
the study of the effect of electric charges at rest and in motion.
materials in which internal magnetic moments spontaneously line up parallel to each other to form domains, resulting in permeabilities considerably higher than unity (in practice, 1.1 or more); examples include iron, nickel, and cobalt.
homopolar magnetic bearing
a magnetic bearing in which the rotating member always experiences a magnetic field of the same polarity.