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# Electrical Power

## 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, …

## Overhead Line Insulators: Types, Material, Properties

The overhead line conductors are open and do not have any insulated coating over them. Those conductors should be supported on the poles or towers in such a way that current from conductors does not flow to earth through supports, that is, line conductors must be properly insulated. This is …

## Types of Tariff in Electricity | Electricity Tariff: Definition, Examples, Characteristics

The electrical energy that is produced in a power station is delivered to a large number of consumers. The consumers can be convinced to use electrical energy if it is sold at a reasonable price. Here comes the idea of tariffs. Definition: A tariff is the schedule of rates structured …

## Smart Grid: Applications & Components

The Smart Grid Services/Applications refers to systems, including computers, programs, databases, people, and operational support to manage the applications. The Smart Grid Components refer to the devices, sensors, and controllers that provide information to the Smart Grid Services/Applications and receive the command to effect control of devices. Smart Grid Services/Applications …

## Smart Grid: Definition, Goals, Objectives, NIST Conceptual Model

Definition: Smart Grid is a new electricity network, which highly integrates the advanced sensing and measurement technologies, information and communication technologies (ICTs), analytical and decision-making technologies, automatic control technologies with energy and power technologies and infrastructure of electricity grids. Some important aspects of what ‘smart’ are listed below: Observability: It …

## Low Voltage (LV) Distribution System

Most European countries use 230/400 V for low voltage (LV) distribution, or in some cases 240/415 V instead. The majority of residential customers receive a single‐phase supply (i.e. one phase conductor and the neutral) which terminate at the customer’s premises via a service drop (or service connection). These conductors frequently run from the overhead …

## What Is A Smart Grid and How Does It Work | Smart Grid Characteristics

Smart Grid is characterized by a series of integrated technologies, methodologies, and procedures for planning and operation of electrical systems, being favored by the increase of resources related to information, communication, and engineering technologies. Another feature is the diversity of application areas, e.g., energy technologies, transportation efficiencies, utility transformations, and …

## Electrical Power System Components

The electrical grid in North America is a combination of various elements that provide a means of taking electrical power from where it is produced to where it used. The electrical grid is defined as an interconnected network of power stations, transmission lines, and distribution stations that transmit electrical power …