One method of protecting sensitive equipment against power interruptions is the uninterruptible power supply (UPS). The UPS has become very popular as the cost of power electronics has decreased. Uninterruptible Power Supply Working Figure 1 shows the principles of operation of an electronic UPS. Single- or three-phase power is obtained …

Read More »## Where do harmonics come from | Causes of Harmonics in Power System

Any electrical load that does not have a linear relationship between the voltage applied to it and the current through it will cause harmonic currents in the power system. To consider what is meant by a linear load, consider Figure 1. Figure 1(a) shows a sinusoidal voltage and the current …

Read More »## Harmonics in Power System

Ideally, all voltages and currents in the power system should be single-frequency sinusoids (60 Hz in North America). The actual power system, however, contains voltage or current components, called harmonics, whose frequencies are integral multiples of the power system frequency. The second harmonic for a 60 Hz system is 120 …

Read More »## Difference between Star and Delta Connection

This article covers the key differences between star and delta connection on the basis of several important factors such as their configuration, voltage, current, power, motor speed, neutral point, number of turns, insulation level, and applications. In Delta connection, phase sides are connected in a cyclical arrangement in order to …

Read More »## Difference between Intrinsic and Extrinsic Semiconductor

This article covers the key differences between intrinsic and extrinsic semiconductor materials on the basis of purity, conductivity, uses, energy gap, temperature, and examples. An intrinsic semiconductor is the one which is made of the extremely pure semiconductor material. They have the equal number of holes and electrons so do …

Read More »## Difference between induction motor and synchronous motor

This article covers the key differences between the induction motor and synchronous motor on the basis of several important factors such as Construction, Starting Mechanism, Excitation, Speed Control, Power Factor, Load Change, Cost, Slip, Efficiency, and Applications. The induction motor is the most common type of AC motor. It is …

Read More »## Power in an AC Circuit

In an alternating-current circuit, power is dissipated in a resistor, but not in a pure inductor or a capacitor. Because the current in an RL circuit lags the supply voltage by an angle ϕ, the amount of useful power supplied to the circuit is proportional to Cosϕ. Similarly, in an …

Read More »## Latches and Flip Flops

The goal of this module is to explore Sequential Logic and its functional building blocks and to describe the operations of latches and flip-flops in digital circuits. Objective A learner will be able to: Explain the difference between combinatorial logic and sequential logic. Define positive and negative edge triggering. Explain …

Read More »## Logic Simplification Karnaugh map

The goal of this module is to provide learners with tools for reducing Boolean algebra expressions to their simplest form. Objectives The learner will be able to: Reduce Boolean expressions using the 14 Boolean rules. Simplify complex Boolean algebra expressions using the 14 Boolean rules and apply DeMorgan’s Theorem. Carry …

Read More »## Combinational Logic Circuits using Logic Gates

The goal of this module is to provide learners with tools for understanding the operations of XNOR and XOR gates and enable learners to apply Boolean rules to find the Sum of Products (SOP) and the Product of Sums (POS). Objectives The learner will be able to: Explain the operation …

Read More »## Basic Logic Gates and Boolean expressions

The goal of this module is to enable learners to apply basic logic gates and Boolean expressions to digital circuits. Objectives A learner will be able to: Explain the difference between analog and digital quantities Give examples of binary numbers and describe their structure Give examples of hexadecimal and octal …

Read More »## Number Systems in Digital Electronics

The goal of this module is to provide learners with skills and practice necessary to enable them to convert between number systems used in digital electronics. Objective The learner will be able to Explain the difference between analog and digital quantities Give examples of binary numbers describe their structure Give …

Read More »## Buck-Boost Transformer Working Principle

A buck-boost transformer is a type of transformer which is primarily used to adjust the voltage level applied to various electric equipment. Buck-boost transformers are utilized in in several applications such as uninterruptible power supplies (UPS) units for computers. When an existing AC electrical circuit suffers from excessive voltage drop …

Read More »## Starting Methods of Three Phase Induction Motor

Three-phase Induction motors draw six or more times rated current when started at rated voltage. Such high currents may pose serious problems for the motor and the electrical system when large motors are started. One way to reduce the starting current is to start the motor at reduced voltage. After …

Read More »## Three Phase Induction Motor Performance

Using the equivalent circuit of the three-phase induction motor and some additional information about the mechanical and core loses, one could calculate the performance of the three-phase induction motor from no-load to full-load. Figure 1 shows a set of generic curves of efficiency, current, power factor, and slip for an …

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