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# Electrical Power

## 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 …

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 …

## Power Triangle and Power Factor in AC Circuits

An inductor is a coil of wire having resistance and, if an iron core is used, eddy current and hysteresis losses are produced when an ac current is applied. For example, a 40ΩW fluorescent-lamp ballast typically has a resistance of 36 Ω, draws 0.4 A and consumes 10 W. The …

## Alternative Ways of Generating Electricity

At the present time, we are seeing a growing number of small energy suppliers using a variety of renewable energy sources to produce electricity. Electricity from Wind Power Wind power systems convert the kinetic energy in wind into electric energy. Wind turbines are installed in locations with strong, sustained winds. Figure 1 shows a …

## Paralleling of Generators and Synchronization

The most common generator used in production of electrical power is the three-phase generator. It consists of a rotating magnetic field inside three sets of windings. See Figure 1, part A. The three sets of windings are referred to as the armature of the generator. The armature provides power for …

## Voltage and Currents in Star (Wye) and Delta Connected Loads

Most of the AC power used today is generated and distributed as three-phase power, which implies three sinusoidal sources, each out of phase with the other. The primary benefit is efficiency: The weight of the conductors and other components in a three-phase system is much lower than that in a single-phase …

## Instantaneous and Average Power Formula

When a linear electric circuit is excited by a sinusoidal source, all voltages and currents in the circuit are also sinusoids of the same frequency as the source. Figure 1 depicts the general form of a linear AC circuit. Figure 1 Time and frequency domain representations of an AC circuit. …

## Resistance and Impedance in an AC Circuit

The i -v relationships of resistors, capacitors, and inductors can be expressed in phasor notation. As phasors, each i-v relationship takes the form of a generalized Ohm’s law: $\text{V=IZ}$ where the phasor quantity Z is known as impedance. For a resistor, inductor, and capacitor, the impedances are, respectively: \$\begin{matrix}{{Z}_{R}}=R & …

## Solid State Motor Starters

A solid-state motor starter is an electronically operated switch (contactor) that uses solid-state components to eliminate mechanical contacts and includes motor overload protection. Solid-state motor starters are connected into a circuit after the disconnect/overcurrent protection device and before the motor. Solid-state motor starters include motor overload protection and are controlled by …

## Solid State Relay Vs Electromechanical Relay

Electromechanical relays (EMRs) and Solid state relays (SSRs) are designed to provide a common switching function. An EMR provides switching through the use of electromagnetic devices and sets of contacts. An SSR depends on electronic devices such as SCRs and triacs to switch without contacts. In addition, the physical features …

## Solid State Relay Switching Methods

The solid state relay used in an application depends on the load to be controlled. The different SSRs are designed to properly control certain loads. The four basic solid state relays are the zero switching (ZS) relay, instant-on (IO) relay, peak switching (PS) relay, and analog switching (AS) relay. Zero …

## Solid-State Relay Circuit Components

A relay is a device that controls one electrical circuit by opening and closing another circuit. A small voltage applied to relay results in a larger voltage being switched. A solid-state relay (SSR) is a switching device that has no contacts and switches entirely by electronic means. An SSR uses a …

## Solid State Relay Problems

Temperature rise is the largest problem in applications that use solid state relay (SSR). As temperature increases, the failure rate of SSRs increases. As temperature increases, the number of operations of an SSR decreases. The higher the heat in an SSR, the more problems occur. See Figure 1. The failure …

## Electric Power Distribution System Basics

A one-line diagram for an electric power distribution system is an electrical drawing that uses single lines and graphic symbols to illustrate the current path, voltage values, circuit disconnects, fuses, circuit breakers, transformers, and panelboards. One-line diagrams use the most basic symbols because the intent of the drawing is to …

## Distribution Switchboard | Panelboard | Function & Components

Electrical power is delivered to industrial, commercial, and residential buildings through a distribution and transmission system. Once the power is delivered to a building, it is up to the building electrician to further distribute the power to where it is required within the building. Switchboard Definition A switchboard is a …

## Electrical Power: Transmission & Distribution | Distribution Substation Components

Today, most electrical power is distributed through a network of transmission lines (conductors), substations (transformers), and generating equipment from relatively large, centralized power-generating stations directly to the customer. These large, centralized power-generating stations are located near abundant energy sources such as coal, oil, and natural gas. Large, centralized power-generating stations …

## Three-Phase Electricity Explained

In Figure 1 a single load connected to a source constitutes a simple circuit. The source is represented by a winding because all generators have windings in them. Figure 1 A single circuit consisting of a source and a load. Figure 2 illustrates three of these assumed AC circuits near each other. Intentionally, the generators …

## Corona Effect in Transmission Lines | Factors Affecting Corona

Corona Definition: When an alternating potential difference is applied across two conductors whose spacing is large as compared to their diameters, there is no apparent change in the condition of atmospheric air surrounding the wires if the applied voltage is low. However, when the applied voltage exceeds a certain value, …