Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

interrupting capacity

See interrupting rating
interrupting rating
for a circuit breaker, fuse, or switch, the maximum fault level that the device can safely interrupt. The interrupting rating can be expressed in terms of amps or volt-amps.
intrinsic
term associated with the inside or interior. In devices and device modeling, intrinsic refers to that part of the device or model associated with the active semiconductor structures that control device operation, or provide the desired functions.
intrinsic coercive force
the demagnetizing field required to reduce the intrinsic induction to zero; the x-intercept of the intrinsic demagnetization curve. This quantity is used to gage the field required to magnetize a material and its ability to resist demagnetization.
intrinsic demagnetization curve
the second quadrant portion of the hysteresis loop generated when intrinsic induction (Bi )is plotted against applied field (H ), which is mathematically related to the normal curve; most often used to determine the effects of demagnetizing (or magnetizing) fields.
intrinsic impedance
(1) the impedance presented when a source is open-circuited.

(2) a characteristic parameter associated with a medium that is the ratio of the magnitudes of the transverse components of the electric field intensity and magnetic field intensity for a wave propagating in a given direction. It has units of ohms.
intrinsic induction
the vector difference between the magnetic induction and the applied external magnetic field, or the magnetic field established by the magnetic material itself.
inverse-time circuit breaker
a circuit breaker in which the allowed current and time are inversely proportional. It contains a thermal element and a magnetic element in series. The thermal element is designed to trip as a result of heating over time in response to overload currents, while the magnetic element is designed to trip magnetically, with no intentional time delay, in response to short-circuit currents. Also called a thermal-magnetic circuit breaker.
inverter
switching circuit that converts direct current to alternating current.

An inverter can be classified as a natural-commutation type or a self-commutation type. The output AC of a natural-
commutated inverter is synchronized to the AC line. This type of inverter is a thyristor rectifier in a reversed order. The output AC of a self-commutated inverter is independent, i.e., both the frequency and amplitude may be controlled. Commonly used self-commutated inverters include square-wave inverters and PWM inverters.
irreversible loss a reduction in the magnetization of a permanent magnet that can only be recovered by remagnetizing the material, usually caused by temperature extremes, reversing fields, or mechanical shock.
ISO
International Standards Organization.
isolation
(1) the separation of a part from other parts of the system so that the effects of undesired changes in the system are not seen by the separated part.

(2) a figure (usually expressed in decibels) to describe how well a transmitting device (source) and receiving device (receiver) are separated electrically; the amount of (usually undesirable) signal appearing at the receiver from the transmitting source from an undesirable signal path such as leakage in a coupler, mutual coupling, or multipath.
isolation switch
See bypass switch
isolation transformer
a transformer, typically with a turns ratio of 1:1, designed to provide galvanic isolation between the input and the output.
isolator
(1) a two-port passive device based on the Faraday effect. Signals passing in one direction suffer minimal loss, however, in the reverse direction they are strongly attenuated.

(2) in optics, a device inserted in an optical fiber that prevents optical power from flowing in the reverse direction from the transmitted power. Optical fiber isolators can be made either dependent or independent of the polarization direction of the optical energy in the fiber.
International Electro-technical Commission
the international standards and conformity assessment body for all fields of electrotechnology.
See IEC
jumper
a plug or wire used for setting the configuration of system. It can be used for changing the hardware configuration by forcing some line to be high or low. It is used to change software configuration (especially on embedded systems) when the status of the jumper is read by the microprocessor.
jumping jack
a voltmeter.
leakage
the flux in a magnetic circuit that does not do any useful work.
leakage flux
the flux that does not link all the turns of a winding or in coupled circuits, flux that links one winding but not another. For example, the magnetic flux produced by the primary winding of a transformer that is not coupled to the secondary winding.
leader
an elongated region of ionized gas that extends from one electrode to another just before a high-voltage breakdown.
lateral
(1) a lateral on a primary distribution line is a short tap from the main distribution line which serves a local set of loads. Single phase laterals are common in residential districts.

(2) a three-phase or single-phase power line which supplies the distribution transformers along a street
See feeder
Powered by The Filipino Engineer