Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

shunt peaking
use of a peaking coil in a parallel tuned circuit branch connecting the output load of one amplifier stage to the input load of the following stage, in order to compensate for high frequency loss due to the distributed capacitance of the two stages.
shunt reactor
a reactor intended for connection in shunt to an electric system to draw inductive current.
Siemens
Siemens, Ernst Werner von (1816-1892) Born: Lenthe, Hanover, Germany

is best known for the German and British companies that bear his name. Siemens was a strong believer in basic research, as well as an avid inventor. His early inventions included an improved guttapercha wrapped telegraph cable that allowed his companies to secure a number of lucrative cable contracts. His discovery of the dynamo principle, and his use of this in heavy-current applications, allowed his companies to become pioneers in devices to generate electricity and rail applications. Siemens' belief in basic research made him a champion of standards and research institutions that he helped
to establish.
signal-to-noise ratio (SNR)
the ratio of the average power of the information signal component to the average power of the noise component in a signal consisting of the sum of an information signal component and a corrupting noise component. It is a unitless quantity.
SIL

See surge impedance loading
simplex
term used to describe a method of winding the armature of a commutated electric machine in which consecutive coils are placed in adjacent coil slots around the periphery of the rotor. In a lap winding, this produces two parallel electrical path between brushes for each pole pair. In a wave winding, a simplex arrangement produces two parallel electrical paths between brushes regardless of the number of poles. See also duplex, multiplex.
sine transform
usually refers to the discrete sine transform. It also refers to a continuous time transform similar to the Fourier transform.
sine-squared pulse
pulse string made from a standard sinewave with an added DC component equal to one-half of the peak-topeak value of the sine wave. The pulse string is, therefore, always positive in value.
sinewave brushless DC
a permanent magnet brushless motor with sinusoidally distributed stator phase windings. More
commonly known as permanent magnet synchronous machine.
single dwell detector
a detector in a communications receiver based on a decision on a transmitted symbol being made after a single correlation of the received signal with a reference signal. Compare with multiple dwell detector.
single electron transistor
solid state device that performs electronic functions using a single transistor's electron.
single line to ground fault
a fault on a three phase power line in which one conductor has become connected to ground.
single machine infinite bus system
a model of a power system consisting of a single generator working into an infinite bus which represents the remainder of the system.
single phase to ground fault

See single line to ground fault
single-element fuse
a fuse that is constructed with a single fusible element. It does not meet the standard definition of time-delay.
single-phase inverter
an inverter with a single-phase AC voltage output. Half-bridge and full-bridge configurations are commonly used.
single-phase rectifier
a rectifier with a single-phase AC voltage input. See also half-wave rectifier and full-wave rectifier.
single-phasing
a condition that occurs when a three-phase motor has an open circuit occur in one of the three lines. The motor continues to operate with one line to line voltage as a single-phase motor, with an increase in noise, vibration, and current. Proper overload protection should detect the higher current and shut down the motor after some time delay.
single-pole double-throw (SPDT)
a switch that has a common port and two output ports. Among these two ports, only one selected port can be connected to the common port.
single-pole reclosing
the practice of clearing a fault which appears on one phase of a three-phase electric power line by disconnecting and reclosing only that phase as opposed to opening and reclosing all three phase conductors.
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