Discrete Time System

When the time variable t takes on the discrete values t=kT, k=…,-2,-1, 0, 1, 2… the system is said to be discrete – time system.

Dependent Sources

 Voltage or current source whose value linearly depends upon the value of voltage or current of other elements in the circuit.

Digital Multimeter

A digital multimeter (DMM) is a multifunctional meter that displays its electrical quantitative values on an LCD screen. 


A logarithmic unit for expressing the difference between two sound, power, voltage or current levels.

Direct Current

Current that continues to flow in the same direction is called direct current and remains constant.


The material between two plates of a capacitor is non-conducting or insulating. This insulating material is called dielectric. An example of some dielectrics is air, ceramic, Formica and Teflon.

Dielectric Strength

The dielectric strength of a material is a measure of how much voltage it can withstand, before breaking down.


Acicular (needle-shaped), microscopic crystals containing a very large number of atoms whose spinning electrons result in a net magnetic effect in a particular direction.

DC Machine

An electromechanical conversion device whose armature voltage and current, as well as field voltage and excitation current, are all DC.

Developed Power

 The power Converted from electrical to mechanical or from mechanical to electrical. 

Diagonal matrix

A Square matrix in which all the elements, not in the principal diagonal, are equal to zero; that is, aij=0 for all i≠ j.

Direct-axis synchronous reactance, Xd

The ratio of the sustained fundamental component of armature voltage that is produced by the total direct-axis flux due to direct-axis armature current to the fundamental component of this current, the machine running at rated speed.

Digital Multimeter

 A meter used to measure electrical quantities that can measure different electrical quantities such as voltage and amperage and displays the reading as numbers or digitally.


A set of electronics that gives precise control over electric motors including speed and direction.

Discrete input module

Hardware that is capable of receiving only one input consisting of either a high or low.

About Ahmad Faizan

Mr. Ahmed Faizan Sheikh, M.Sc. (USA), Research Fellow (USA), a member of IEEE & CIGRE, is a Fulbright Alumnus and earned his Master’s Degree in Electrical and Power Engineering from Kansas State University, USA.

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