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Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

ambient temperature
the temperature of the air or liquid surrounding any electrical part or device. Usually refers to the effect of such temperature in aiding or retarding removal of heat by radiation and convection from the part or device in question.

American National Standards Institute (ANSI)
The U.S. organization that recommends standards for metrology, drawing
symbology and numerous other facets for products and industries.

ammeter
an instrument for measuring electric current in amperes.

amortisseur winding
See damper winding
ampacity
the maximum current which can be safely carried by a conductor under specified conditions.

ampere interrupting rating
the interrupting rating of a device expressed in amps (often rms symmetrical amps).
See MVA interrupting rating
amplidyne
a special generator that acts like a DC power amplifier by using compensation coils and a short circuit across its brushes to precisely and fastly control high powers with low level control signals.

analog-to-digital (A/D)
conversion a method by which a continuously varying signal (voltage) is sampled at regularly occurring intervals. Each sample is quantized to a discrete value by comparisons to preestablished reference levels. These quantized samples are then formatted to the required digital output (e.g., binary pulse code words).
The A/D converter is “clocked” to provide updated outputs at regular intervals. In order not to lose any baseband information, sampling must occur at a rate higher than twice the highest incoming signal frequency component.

analog-to-digital (A/D)
converter a device that changes an analog signal to a digital signal of corresponding magnitude. This device is also called an encoder, ADC, or A/C converter.
angular frequency
the rate of change of the phase of a wave in radians per second.

ANSI
American National Standards Institute, a body which administers numerous industrial standards in the USA including several which pertain to electric utility construction practices.
See American National Standards Institute
antenna
a device used to couple energy from a guiding structure (transmission line, waveguide, etc.) into a propagation medium, such as free space, and vice versa. It provides directivity and gain for the transmission and reception of electromagnetic waves.
antenna beamwidth
the effective angular extent of the antenna radiation pattern usually specified between points of fixed amplitude relative to the main lobe gain (e.g., -3 dB points).

antenna gain
the maximum ratio of an antenna's ability to focus or receive power in a given direction relative to a standard; the standard is usually an isotropic radiator or a dipole. The gain includes the efficiency of the antenna.
antenna Q
ratio of the energy stored to the energy dissipated (ohmically or via radiation) per cycle.

antifuse
a fuse-like device that when activated becomes low-impedance.

antiparticle
a particle having the same mass as a given fundamental particle, but whose other properties, while having the same magnitude, may be of opposite sign. Each particle has a partner called an antiparticle. For example, electrical charge in the case of the electron and positron, magnetic moment in the case of the neutron and antineutron. On collision a particle and its antiparticle may mutually annihilate with the emission of radiation. Some properties of the antiparticle will be identical in magnitude but opposite in sign to the particle it is paired with.

antipodal
symmetry created by simultaneously mirroring an object in both the X and Y axes.

antireflection coating
See antireflective coating
antireflective coating (ARC)
a coating placed on top or below the layer of photoresist to reduce the reflection of light, and hence reduce the detrimental effects of standing waves or thin film interference.