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Commonly used terms in the Electrical industry.
induction regulator
See
induction voltage transformer
insulation class
specification of insulating material. Primarily determined by the maximum temperature that the material can withstand. The class of insulating system used in a transformer or electrical machine is a key factor in determining its rated load.
insulation coordination
the practice of selecting the insulation of a power system such that breakdowns from overvoltages (such as from a lightning strike) will occur at points where the least harm will result.
insulation resistance
measured value of electrical resistance of the insulation of a product or device.
insulator
a device designed to separate and prevent the flow of current between conductors. Properties of the dielectric (insulating) material and geometry of the insulator determine maximum voltage and temperature ratings.
insulator string
a chain of two or more strain insulators that are coupled together to increase the total insulation level of the assembly.
intermittent fault
a fault that appears, disappears, and then reappears in a repeated manner.
left-hand circular polarization
the state of an electromagnetic wave in which the electric field vector rotates anticlockwise when viewed in the direction of propagation of the wave.
line to line fault
a fault on a three phase power line in which two conductors have become connected.
load-pull
the systematic variance of the magnitude and phase of the load termination of a device under test.
metal-insulator-metal (MIM)
capacitor a capacitor, which has a thin insulator layer between two metal electrodes. Generally, this capacitor is fabricated in semiconductor process, and this insulator layer provides high capacitance. Two extreme behaviors of a capacitor are that it will act as an open circuit to low frequencies or DC (zero frequency), and as a short frequency at a sufficiently high frequency (how high is determined by the capacitor value).
See
thin film capacitor
multiplex
(1) to use a single unit for multiple purposes, usually by time sharing or frequency sharing.
multiplexer
(2) the armature winding of a commutated electrical machine in which multiple, identical coil windings are placed on the rotor. In general, the number of the "plex" describes the total number of parallel windings between brush positions and, thus, also the multiplier on the number of parallel paths between brushes that would be provided by a simplex winding. For example, a duplex winding will have twice as many parallel electrical paths between brushes as a simplex winding, a triplex winding will have three times the number of paths, etc. See
simplex
,
duplex
,
reentrancy
.
multiplexer
a combinational logic device with many input channels and usually one output, connecting one and only one input channel at a time to the output.
multiplexing
(1) the process of transmitting a large number of information units over a smaller number of channels or lines. For example, if we have N independent signals that we want to transmit, then without using a multiplexer we need N independent channels to do so. Using a multiplexer to control the flow of these signals in only one channel reduces the number of wires, thus decreasing cost and increasing efficiency. Multiplexing is the superimposition of multiple signals to make up one signal. This is done to make the transmission of the signals efficient. Signals are multiplexed at the sending end of communication systems, and demultiplexed at the receiving end, in order to obtain the original signals.
(2) of or being a communication system that can simultaneously transmit two or more messages on the same circuit or radio channel.
multispeed motor
a motor that can be operated at any one of two or more definite speeds. For DC and induction motors, the speed settings are practically independent of the load, although the speed may vary with load for certain types of motors. Multispeed induction motors typically have two or more sets of windings on the stator with a different number of poles, one of which is excited at any given time.
oil-paper insulation
an insulation scheme used in transformers and cables in which conductors are insulated with heavy paper impregnated with a dielectric oil.
permanent fault
a fault that remains in existence indefinitely if no corrective actions are taken.
phase-to-phase fault
a fault with two transmission lines being short circuited.
pin insulator
an electric insulator which is concentric with a hollow, threaded hole so that it can be screwed onto a steel pin mounted on a utility pole or crossarm.
post insulator
an electrical insulator which is supported by its firmly-bolted base, either in an upright position or cantilevered out horizontally from a utility tower.