Synchronous Machine as Generator and Motor

Figure 1 shows a cross-sectional view of a salient-pole synchronous machine. The armature windings are shown as concentrated windings, but in reality, they would be distributed. Such machines can be operated either in Motor or Generator mode. Motor Operation For motor operation, a balanced three-phase set of voltages is applied …

Read More »

DC Machine Construction and Operation

Figure 1 shows elementary permanent- magnet machine. It is very similar to the AC machine; however, instead of a pair of slip rings to connect to the ends of the coil, there is a single split ring. Each end of the coil is connected to one-half of the ring, and …

Read More »

AC Motor and Generator Working Principle

Figure 1 shows a simple, single-turn, permanent- magnet machine. The single-turn coil is free to rotate between two magnetic poles of opposite polarity. Magnetic flux goes from a north pole to a south pole, so there will be magnetic flux in the region between the poles where the coil is …

Read More »

Properties of Magnetic Materials

Magnetic domains in a ferromagnetic material.

Consider the simple model of the atom in Figure 1. Electrons move around the nucleus like the earth around the sun. This electron motion is a small electric current, and anywhere there is a current, there is a magnetic field (moment). Electrons also spin around their axes like the earth. …

Read More »

Harmonics in Power System

Approximation to a square wave using the first five

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

Instantaneous Power

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

3 variable k 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 »