DIAC Operation

DIAC | Operation | Characteristics | Relaxation Oscillator

The diac is a two-terminal three-layer bi-directional trigger device. It is a thyristor device but does not have a gate terminal. The diac was developed specifically as a trigger device to provide bi-directional trigger pulses. The construction of a diac is complex and beyond the scope of this book. The …

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Three Phase Induction Motor Working Principle

Three Phase Induction Motor Working Principle

For its operation, a three-phase induction motor is dependent on a rotating magnetic field being established by the AC windings. The three separate windings are installed in the stator at 120°E intervals to one another and provide a fixed number of poles for each phase. This is shown diagrammatically in Figure …

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AC Resistive Circuit | Analysis | Examples

AC Resistive Circuit Analysis Examples

This guide covers AC Resistive Circuit analysis along with several solved examples to compute total resistance, current, and power in an AC Circuit. When an alternating voltage is applied to a circuit, it causes an alternating current of the same frequency to flow through the circuit. For purely resistive AC circuits the …

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DC Motor | Types | Working | Characteristics

DC Motor Types Working Characteristics

DC Motors and generators have the same basic construction and the typical machine can be used in both capacities. For the DC motor to be useful it must develop torque, or a turning effect. When electrical energy is applied to a DC machine, current flows in the armature conductors and …

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Circuit Breaker Terms and Definitions

Circuit Breaker Terms and Definitions

Here, we have covered over 100 circuit breaker terms and definitions. Alternating current (AC): Current that reverses its direction of flow at regular intervals. Arc: A sustained discharge of electricity across a gap in a circuit or between electrodes, usually accompanied by the electrodes (contacts) being vaporized and/or melted by the extreme …

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Electric Machine Losses and Efficiency | Examples

Electric Machine Losses and Efficiency

Electric Machine Losses Mechanical Losses Mechanical losses result when any electric machine operates. It is simply not possible to make a machine 100 per cent efficient. In electric machines the losses are minimal, however, and electric machines may approach 98 per cent efficiency. The normal losses in a rotating electric …

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Single Phase & Three Phase Transformer Construction

Single Phase & Three Phase Transformer Construction

Single-Phase Transformer Cores A transformer consists of a common magnetic circuit linking the primary and secondary windings. The form of construction is determined by the arrangement of the laminations and the way they are stacked together. Figure 1 shows two methods for making up the stack for a transformer core.  Figure 1(a) shows …

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Three-Phase Induction Motor

Three-Phase Induction Motor | Construction | Parts

Like all motors, a three-phase induction motor contains a stator (the stationary part) and a rotor (which rotates). Each contains electrical windings that carry current and thus creates a magnetic field. The interaction of the magnetic fields creates the torque that rotates the rotor and the load. Figure 1 demonstrates …

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Secondary Batteries | Types | Working

Secondary Batteries | Types | Working

The main difference between primary batteries and secondary batteries is the ease with which secondary batteries can be recharged. Lead–Acid Batteries When compared with other types of battery of comparable size and weight, lead–acid batteries can deliver higher current for short bursts. Variations in plate construction allow for individual specialized …

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Three-Phase Power Measurement Methods

Three-Phase Power Measurement Methods

Different methods are utilized in order to measure three-phase power in a three-phase circuit. In this article, we are going to discuss the following methods in detail: One Wattmeter Method (4-Wire System) One Wattmeter Method (3-Wire System) Two Wattmeters Method (3-Wire System) Three Wattmeters Method (3-Wire System) Three Wattmeters Method …

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Advantages of Three-Phase System

Advantages of a Three-Phase System

A three-phase system has three generating windings, each out of phase with the other two by 120ºE. Figure 1 (a) illustrates a simplified three-phase alternator with three windings A, B and C at 120ºE intervals. Figure 1 (b) shows the waveforms generated by the three windings, illustrating the phase shift between waveforms, and Figure …

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Resistors in AC Circuits

Resistors in AC Circuits

The current flowing through a resistor is determined by Ohm’s Law for any instant of time: I = V/R for any part of the cycle. As you should be aware, when the resistance remains the same, the current is directly proportional to the applied voltage. Therefore, the current waveform for …

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Sine Wave Characteristics

Sine Wave Characteristics

Here are some of the terms used to describe alternating waveforms: 1. A ‘periodic function’ is an alternating wave that repeats itself in a cycle. 2. The number of times a wave repeats itself in one second is called the ‘frequency’ of that wave and is expressed in cycles per …

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Magnetization Curve Explanation

magnetization curve

Magnetization Curve Definition A curve, or loop, plotted on B-H coordinates showing how the magnetization of a ferromagnetic material varies when subjected to a periodically reversing magnetic field, is known as Hysteresis Loop or Magnetization Curve. Non-Magnetic Materials The reluctance of non-magnetic materials is not affected by the density of flux in those …

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Magnetic Reluctance (Rm)

Magnetic Reluctance (Rm) | Definition | Formula | Example

Some materials require high magnetizing forces to align their atomic dipoles in the same direction, while others are readily magnetized by small forces. All materials offer some opposition to being magnetized and the term used to describe this opposition is ‘magnetic reluctance’. Magnetic Reluctance Formula Reluctance is comparable with resistance in …

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Magnetic Flux Density (B)

Flux Density (B) Definition Formula Example

Magnetic Flux density is the measure of the number of magnetic lines of force per unit of cross-sectional area. The general symbol for magnetic flux density is B and the unit is the weber per square meter (Wb/m2). One weber per square meter is called a tesla (T). If both …

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Magnetic Field Intensity

Magnetic Field Intensity | Definition | Formula

The m.m.f. required to magnetize a unit length of a magnetic path is termed the magnetizing force or magnetic field intensity (H) for that portion of the magnetic circuit. The magnetic field intensity is applicable only to that section of the magnetic circuit, made of the one material and with …

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Magnetomotive Force (MMF)

Magnetomotive Force (MMF) Definition Formula Unit Example

The force required to create a magnetic field is called the magnetomotive force, abbreviated to m.m.f. with a general symbol Fm. The magnetomotive force is the force that creates the magnetic field. The m.m.f. acts like the electromotive force in an electric circuit and is the force necessary to set …

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