## Electrical Formulas | Electrical Formulas Sheet

A Absolute Permittivity ${{\varepsilon }_{o}}=8.84*{{10}^{-12}}$ Active Power $\text{P=VICos(}\theta \text{) Watt}$ Apparent Power $\text{S=VI volt-amp}$ B C Capacitance $\text{C=}\frac{\text{ }\varepsilon {{\text{ }}_{\text{o}}}\text{ }\varepsilon {{\text{ }}_{\text{r}}}\text{A}}{\text{d}}$ Where, εo= Absolute Permittivity εr= Relative Permittivity A=Plates Area d= distance between plates Conductance $\text{Conductance}=\frac{1}{\text{Resistance}}=\frac{1}{\text{R}}$ Capacitive Reactance ${{\text{X}}_{\text{C}}}\text{=}\frac{1}{2\pi fC}$ Capacitive Susceptance ${{\text{B}}_{\text{C}}}\text{=}\frac{1}{{{\text{X}}_{\text{C}}}}$ Current in Series Circuit …

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## N

Nyquist criterion The Nyquist criterion is a frequency domain tool which is used in the study of stability. To use this criterion, the frequency response data of a system must be presented as a polar plot in which the magnitude and the phase angle are expressed as a function of …

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## O

Open-Loop Control System An open loop system is characterized by the fact that the input signed is processed without being affected by the output. Oscilloscope Oscilloscope is most widely used to display amplitude and period of the signal as well as the shape of the wave Ohm The unit of …

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## P

Permeability Permeability is the measure of the ease, with which magnetic lines of force pass through a given material. Proton A positively charged particle with considerable mass. Phase rotation meter Phase rotation meter is a device used to determine the phase order of a three-phase electrical system. Parallel Circuit In …

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## R

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 …

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## 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 …

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## 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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## U

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

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## 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 …

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## 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 …

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## 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 …

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## Types of Resistors | Power Resistor

Resistor An element used to reduce supply voltages to some desired value or to limit current. A resistor is a small component of two leads. A wide variety of resistors is used in the electronics industry today. Carbon composition resistor The carbon composition resistor is the basic mass-produced resistor of …

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## 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 …

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## 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 …

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