A high voltage source is required to pass a measurable current through such resistances. Thus, the megger is essentially an ohmmeter with a sensitive deflection instrument and a high voltage source. As illustrated in figure (1), the voltage is usually produced by a hand-cranked generator. The generated voltage may …

Read More »## PMMC Instrument Working Principle | Permanent Magnet Moving Coil Instrument

Figure 1 shows the basic construction of a PMMC instrument. A moving-coil instrument contains principally of a permanent magnet to offer a magnetic field and a small lightweight coil pivoted within the field. A soft iron core is included between the poles of the magnet so that the coil …

Read More »## Sinusoidal Waveform or Sine Wave in Electricity

Because of the importance of sinusoidal functions, I will devote this section to a review of some of their properties. Let us being with the sine wave, $\begin{matrix} v(t)={{V}_{m}}\sin (\omega t) & \cdots & (1) \\\end{matrix}$ Which is sketched in figure (1). The amplitude of the sinusoid is Vm, which …

Read More »## Electric Current | Unit of Electric Current

The primary purpose of an electric current is to move or transfer charges along specified paths. This motion of charges constitutes an electric current, denoted by the letters i or I, taken from the French word “intensite”. Formally, The basic unit of current is the ampere (A), named after …

Read More »## Symmetry Properties of the Fourier series

If a function has symmetry about the vertical axis or the origin, then the computation of the Fourier coefficients may be greatly facilitated. A function f (t) which is symmetrical about the vertical axis is to be an even function and has the property \[f(t)=f(-t)\] For all t. that is, …

Read More »## Phasors in Electric Circuits

The phasor method of analyzing circuits is credited generally to Charles Steinmetz, a famous electrical engineer with the General Electric Company in the early part of this century. To begin, let us recall the general sinusoidal voltage, $\begin{matrix} v={{V}_{m}}\cos (\omega t+\theta ) & \cdots & (1) \\\end{matrix}$ If the frequency …

Read More »## RMS Value| RMS Voltage | RMS Current

Periodic currents and voltages deliver an average power to resistive loads. The amount of power that is delivered depends on the characteristics of the particular waveform. A method of comparing the power delivered by different waveforms is therefore very useful. One such method is the use of RMS or effective …

Read More »## RLC Series Circuit Analysis

When resistance, inductance, and capacitance are connected in series, the circuit is said to be RLC Series circuit. In the RLC Series circuit shown in the figure below, the current is common to all components. The series RLC circuit, shown in figure 1, is the dual of the parallel circuit. …

Read More »## Average Power Formula | Instantaneous Power Formula

In linear networks which have inputs that are periodic functions of time, the steady-state currents and voltages produced are periodic, each having identical periods. Consider an instantaneous power $\begin{matrix} p=vi & \cdots & (1) \\\end{matrix}$ Where v and i are periodic of period T. that is, $\begin{align} & v(t+T)=v(t) \\ & …

Read More »## Parallel RLC Circuit Analysis

When resistance, inductance, and capacitance are connected in parallel, the circuit is said to be RLC Parallel circuit. In the parallel RLC circuit shown in the figure below, the supply voltage is common to all components. One of the most important second-order circuits is the parallel RLC circuit of figure …

Read More »## Inductor Types and Symbols

In spite of the great number of different kinds of inductors, only a few schematic symbols are needed to represent them. Filter Choke A filter choke for a power supply is shown in figure 1 (a), and its symbol is shown in figure 1(b). Fig.1: Iron Core Choke Coil: (a) …

Read More »## RL Circuit Time Constant | Universal Time Constant Curve

When a series RL circuit is connected across a supply, voltage and current transients occur until the current attains a steady-state condition. Consider the circuit figure 1, where R represents the coil’s resistance or an external resistance. When the switched is closed, current begins to flow into the inductance. The …

Read More »## RC Circuit Time Constant | Charging Discharging of Capacitor

When a discharged capacitor is suddenly connected across a DC supply, such as Es in figure 1 (a), a current immediately begins to flow. At time t1 (Figure 1 (b)), the moment the circuit is closed, the capacitor acts like a short circuit. The in-rush current iC is at its …

Read More »## Capacitor Types | Fixed and Variable Capacitors

Variable capacitors Variable capacitors are distinguished by the fact that their capacitance can be changed. Basically, there are two most common types of such capacitors named as a trimmer and rotor-stator capacitors. Rotor-Stator Capacitor The rotor-stator type of capacitor comprises two metallic plate sets. The moving plates are attached conjointly …

Read More »## A

Average Value The sum of the instantaneous voltages in a half cycle wave shape divided by the number of instantaneous voltages. In a sine wave, it is equal to 0.637 times the peak voltage. Analog meters Analog meters are a multifunctional multimeter that operates based on electrical mechanical movement. Autotransformer A …

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