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# Electric Power

It covers articles related to single and three phase power.

## Power System Protection Components

The operation of a power system is affected by disturbances that could be due to natural occurrences such as lightning, wind, trees, animals, and human errors or accidents. These disturbances could lead to abnormal system conditions such as short circuits, overloads, and open circuits. Short circuits, which are also referred …

## Types of Faults in Power System | Unsymmetrical Faults in Power System

The normal operation of the power system at steady state is affected, sometimes dramatically, by the occurrence of such disturbances as overloads and short circuits. Of primary concern are short circuits, not only because they can cause large damage to the affected system component but also because they may lead …

## Symmetrical Components in Power System

The method of symmetrical components is used to solve power system problems involving unbalanced polyphase voltages and currents. It is analogous to the Fourier analysis of nonsinusoidal wave shapes wherein a non-sine wave is resolved into a number of sine waves of various frequencies. In symmetrical components, the unbalanced set …

## Electrical Power System Components

The electrical power system can be divided into three major components: generation (G), transmission (T), and distribution (D) as shown in Fig. 1. The generating system provides the system with electric energy. Transmission and Sub-Transmission Systems The transmission and sub-transmission systems are meshed networks; that is, there is more than …

## Three-Phase AC Power Calculation

In a three-phase AC power distribution circuit, three single-phase AC sources are interconnected in either a wye or delta configuration to form a 3-wire supply in the alternator, transformer, or electric motor, and sometimes a 4-wire supply in the alternator or transformer. If the three single-phase AC sources were in-phase …

## Three-Phase AC Power: Star & Delta Connection

The most economical way to mass produce AC power is by steam turbines that drive large three-phase AC generators (alternators — Figure 1). Figure 1. Steam turbines drive large 3-phase AC generators This is why most electrical-utility power generating plants are located on a river that has been dammed to …

## Single-Phase AC Power

In a single-phase (or 3-phase for that matter) AC electrical power distribution system, both the load current (as electrical utilization loads are connected) and the applied voltage that causes it to flow are transmitted along the length of the circuit conductors varying in amplitude with time and periodically reverse between …

## High-Voltage DC Power Transmission

Advantages and disadvantages of a High-Voltage DC power transmission system should be analyzed in detail. Only then can we raise the question: Is AC energy transmission the most efficient option for the 21st century? AC energy transmission is the most common mode of energy transmission in the world. DC transmission …

## Solar Energy System Cost

A general method of calculation will start from the load energy requirements; determine the local insolation level and the worst month insolation and from this determine the sizing of the storage capacity. From this follows the array power and area, the battery capacity, and eventually the voltage regulator size respectively, …

## Uninterruptible Power Supply (UPS): How It Works | Uninterruptible Power Supply Types

One method of protecting sensitive equipment against power interruptions is the uninterruptible power supply (UPS). The UPS has become very popular as the cost of power electronics has decreased. Uninterruptible Power Supply Working Figure 1 shows the principles of operation of an electronic UPS. Single- or three-phase power is obtained …

## Where do harmonics come from | Causes of Harmonics in Power System

Any electrical load that does not have a linear relationship between the voltage applied to it and the current through it will cause harmonic currents in the power system. To consider what is meant by a linear load, consider Figure 1. Figure 1(a) shows a sinusoidal voltage and the current …

## Harmonics in Power System

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 …

## Load Profile Calculation | Solved Example

The load profile is an approximation of the aggregate energy required from a power system over a particular time period (e.g., years, days, hours). The load profile is demonstrated in a two-dimension graph exhibiting the instantaneous load (in Volt-Amperes) over a certain period of time and presents an easy way …