Zero Voltage Switching (ZVS) Principle

Zero Voltage Switching (ZVS) | Principle | Waveforms

Definition Zero Voltage Switching (ZVS) means that the power to the load (heater or cooler or other device) is switched on or off only when the output voltage is zero volts. A major disadvantage of phase control as a means of controlling load power is the RFI generated when the …

Read More »

Three-Phase Generator

Three-Phase Generator | Construction | Voltage Regulation | Rating

This guide covers three phase generator construction, voltage regulation, its rating, cooling methods, excitation control and several solved examples. The three-phase generator has two main windings: 1. A three-phase AC winding 2. Another winding carrying DC. In most cases the rotor has the DC winding and the stator the AC …

Read More »

Electric Motor Maintenance

Electric Motor Maintenance

This guide covers electrical tests (continuity test, insulation to earth test, and insulation test between windings) and visual tests carried out for electric motor maintenance.  Electrical Tests for Three-Phase Motor Windings The tests applicable to an electric motor are either electrical or visual—usually both. Electrical tests are possibly the easiest …

Read More »

Parallel RC Circuit

parallel-rc-circuit

This guide covers Parallel RC Circuit Analysis, Phasor Diagram, Impedance & Power Triangle, and several solved examples along with the review questions answers. This guide covers The combination of a resistor and capacitor connected in parallel to an AC source, as illustrated in Figure 1, is called a parallel RC circuit.  The conditions that …

Read More »

Parallel RL Circuit

parallel-rl-circuit

This guide covers Parallel RL Circuit Analysis, Phasor Diagram, Impedance & Power Triangle, and several solved examples along with the review questions answers. The combination of a resistor and inductor connected in parallel to an AC source, as illustrated in Figure 1, is called a parallel RL circuit. In a parallel DC circuit, the voltage …

Read More »

Series Resonance in a Series RLC Resonant Circuit

Series Resonance in a Series RLC Resonant Circuit

Circuits in which the inductive reactance equals the capacitive reactance (XL=XC) are called resonant circuits. They can be series or parallel circuits and either RLC or LC circuits. The impedance vector for a typical series RLC resonant circuit is shown in Figure 1 and is summarized as follows: XL and XC are 180 degrees out of phase. XL and XC are equal in value (100 Ω), resulting in a net reactance …

Read More »

Series RLC Circuit

Series-RLC-Circuit-Analysis

This guide covers Series RLC Circuit Analysis, Phasor Diagram, Impedance Triangle, Solved Examples and several Review Questions Answers. A series RLC circuit contains elements of resistance, inductance, and capacitance connected in series with an AC source, as shown in Figure 1. Figure 1 Series RLC circuit diagram RLC Series Circuit Characteristics The characteristics of the RLC series circuit can …

Read More »

Series LC Circuit

series-lc-circuit

This guide covers Series LC Circuit phasor diagram, characteristics, and several solved examples along with review questions and answers. A series LC circuit consists of an inductance and a capacitance connected in series, as shown in Figure 1. Figure 1 Series LC circuit diagram LC Series Circuit Characteristics The characteristics of an LC series circuit can be summarized …

Read More »

RC Series Circuit

rc-series-circuit

This guide covers Series RC Circuit Analysis, its Phasor Diagram, Power & Impedance Triangle, and several solved examples. Recall that current and voltage are in phase for purely resistive AC circuits, while current leads voltage by 90 degrees in purely capacitive circuits. Therefore, when resistance and capacitance are combined, the …

Read More »

RL Series Circuit

RL-Series-Circuit

This guide covers Series RL Circuit Analysis, its Phasor Diagram, Power & Impedance Triangle, and several solved examples. In a purely resistive AC circuit, any inductive effects are considered negligible. Similarly, in a purely inductive AC circuit, any resistive effects are considered extremely small, and as a result they are …

Read More »

DC Servo & Stepper Motor

DC Servo & Stepper Motor working diagram applications

This guide covers DC Servo Motor and Stepper Motor Working Principle, Block Diagrams, and their Applications. Further, it also covers Brushless DC Motor Operating Principle and its Applications. DC Servo Motor Working A DC servo motor is usually defined as any motor that can be remotely controlled by providing negative …

Read More »

Armature Reaction in DC Machine

Armature Reaction in DC Machine

This guide covers armature reaction in DC Machine (Generator and Motor) and how to correct it using Brush Shift, Compensating Winding, and Interpoles. An armature, when rotating in its magnetic field, can have varying values of current flowing in its coils. The current can vary from zero at no load …

Read More »

Single-Phase and Three-Phase System Explained

Single-Phase and Three-Phase Systems Explained

This guide covers single phase and three phase systems along with the Wye (Star) and Delta connections. Three phase system advantages and synchronization process are also discussed in detail. An alternator can be designed to generate single-phase or polyphase AC voltages. Figure 1 illustrates the basic configurations used to generate single-phase, two-phase, and three-phase AC voltages. …

Read More »

Cells and Batteries MCQs with Answers

Cells and Batteries MCQs with Answers

1. Separators are usually placed between opposing plates in leads acid cells to:    A.  prevent the electrodes from touching B.  prevent current flow through the cell C.  ensure that the positive and negative electrodes are connected D.  help with the polarization effect during discharge   2. Gel-type and paste-type …

Read More »

Three Phase AC Circuits MCQs with Answers

Three Phase AC Circuits MCQs with Answers

  1. A three-phase generating system has an efficiency of around:    A.  96% B.  90% C.  66% D.  50%   2. The windings of a three-phase alternator are separated by:    A.  90°E B.  120º E C.  180°E D.  360°E   3. Figure shows the stator winding arrangement of …

Read More »