Reluctance The opposition that a magnetic circuit presents to the passage of magnetic lines through it. Reactance The opposition to the flow of an alternating current by an inductive or capacitive element in the circuit. Resistance Resistance is defined as the measure of opposition to the motion of electrons due …

Read More »## S

SI unit SI units are most widely used units of measurement belong to an international system of units which is also known as SI or Metric System. Shunt A precision resistor connected in parallel with a current indicating meter for the purpose of bypassing a specific fraction of current around …

Read More »## T

Time Invariance In time invariant system, there are no changes in system structure as a function of a time t. Tesla The SI unit of magnetic flux density; equal to 1 Weber per square meter. Time Constant In a capacitor, the time required for a voltage to reach to 63.2 …

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Under-excited The operating condition of a synchronous machine absorbing reactive power.

Read More »## V

VFD Variable Frequency Drive – a technology where the rotational speed of an electric motor is controlled or varied electronically. VAR The unit for reactive power Q. Voltage Drop The voltage drop across a resistance is the product of current time’s resistance (IR). Voltage Source A two-terminal circuit element having …

Read More »## Factors Affecting Capacitance | Dielectric Constant

There are three main factors affecting the capacitance of the capacitors that will be discussed in this tutorial in detail. The SI unit of capacitance is farad, named in honor of the English physicist and chemist Michael Faraday. The unit symbol for the farad is F. capacitance is the ability …

Read More »## Wire Gauge Sizes | Circular mils

In order to compare the resistance and conductor sizes with each other, we need to establish a convenient unit. This unit is the mil-foot (mil-ft). A conductor will possess this unit size if having one mil (0.001 inches) diameter and a length of one foot. The standardized unit for wire …

Read More »## Types of Resistors

Resistors can be classified into different types according to their construction. Wire-wound resistors are made by wrapping high-resistance wire around an insulated cylinder, as illustrated in Figure 1. This type of resistor is generally used in circuits that carry high currents. Large wire-wound resistors are called power resistors and range in size from ½ …

Read More »## Nonlinear Resistors | Characteristics Curves of Nonlinear Devices

In most circuits, we can assume that resistance is constant in relation to current and voltage. This linear relation can be graphically shown in figure 1. Fig.1: Plot of Linear Relation between Current and Voltage For example, if 3V is applied to a certain resistor and 1A flows, then 6V …

Read More »## How to Read Resistor Color Code | Resistor Color Bands

Carbon resistors are color coded- that is, they have several color bands painted around the body near one end- to identify their ohmic values. Other types of resistors are not color-coded; instead, they have their ohmic values and, sometimes, identifying part numbers printed on them. The code has been established by …

Read More »## Resistor Power Rating | Power resistor

The physical size of a resistor is not determined by its resistance but by how much power, or heat, it can dissipate. It electric circuits, the unit of power is the watt (W), named in honor of James Watt. One watt is the power dissipated when one ampere flows under …

Read More »## W

Winding Capacitance A side effect of inductors caused by multiple wraps of wire being in close proximity. Winding Resistance The DC resistance of the wire making up the inductor. Wheatstone bridge Wheatstone bridge is used to measure unknown resistance Weber The SI unit of magnetic flux. Watt Power …

Read More »## Impedance Measurement Theory

The opposition that a circuit offers to the flow of AC is called impedance. By measuring the voltage and current in an AC circuit and utilizing the following equation $Z={}^{V}/{}_{I}$ We can obtain the magnitude of circuit impedance. However, it is often desirable to separate impedance into resistive and reactive …

Read More »## Ohmmeter Basic Concepts and Working Principle

Ohmmeter Definition An ohmmeter is an instrument used to measure the resistance. It is an instrument containing a voltage source and a meter directly calibrated in ohms. Series Ohmmeter One type of ohmmeter is the series ohmmeter, so called because the meter movement is in series with the source of …

Read More »## Trigonometric Fourier Series Solved Examples

Why Fourier series? There are many functions that are important in engineering which are not sinusoids or exponentials. A few examples are square waves, saw-tooth waves, and triangular pulses. Indeed, a function may be represented by a set of data points and have no analytical representation given at all. In …

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