AC & DC Machines:::Introduction

A machine is any device that uses energy to perform some work.A simple machine is a device that transforms the direction or magnitude of a force without consuming any energy.Electrical machines are normally grouped into either AC or DC.
Depending on the area of application both types produce the necessary power required each having its own advantages and disadvantages.
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Corona

Have you ever wondered why high voltage power lines buzz (zszszs sound)? Its because they are producing corona which is interacting with the surrounding air.
 Corona is the process by which current, perhaps sustained, develops from an electrode with a high potential in a neutral fluid, usually air, by ionizing that fluid so as to create plasma around the electrode. The ions generated eventually pass charge to nearby areas of lower potential, or recombine to form neutral gas molecules. Plasma is a fourth state of matter (after solid, liquid, and gas). It is like a gas or liquid, but molecules are separated into atoms, and the outer electrons are stripped off and are freed into the plasma. In comparison, the sun is essentially a big ball of very hot plasma.

Power System Network

A detailed explanation of the conversion and distribution of electric energy from the power station to consumer units.This post describes how electric energy moves from the power generating station through conductors of various sizes to consumers premises.To minimize losses and for economical reasons, electrical energy has to be converted into different magnitudes during transmission and distribution until the consumer load.

Electric Pole in the middle of a Road!!

Is this the 8th Wonder of the world?
In Igemebe North Constituency, Eastern Province-Kenya lies a mysterious and mixed up piece of what many might call an engineering mess.Right in the middle of Wiyara Road stands an electric pole.The completion of the road was to follow the installation of power to the area but the two projects ran in to each other resulting to the installation of an electric pole in the middle of the road.

Introducing AutoCAD Electrical 2010

AutoCAD® Electrical software is AutoCAD® software for controls designers. Purpose-built to create and modify electrical control systems, AutoCAD Electrical includes all the functionality of AutoCAD plus a complete set of electrical CAD features. Comprehensive symbol libraries and tools for automating electrical engineering tasks help save hours of effort, so you can spend more time innovating.
AutoCAD Electrical control design software offers significant productivity gains over AutoCAD. Features like real-time error checking and a library of more than 650,000 electrical symbols help to increase design efficiency, while the familiar AutoCAD environment facilitates a smooth transition. Designers can maintain existing AutoCAD workflows, while adopting the enhanced functionality of AutoCAD Electrical at their own pace.

Easter Sunday Power Blackout in Kenya

Kenya was today put out of power due to a breakdown in one of the power stations.According to KPLC (Kenya Power & Lighting Company) - the sole distribution and transmitting company, two Generators at Gitaru Power Station momentarily broke down leading to a shutdown of the other generators because they could not handle the load. The blackout lasted for an approximately 3hrs (from 1pm to 4pm) and was soon corrected by the engineers.Gitaru power station is the biggest station in terms of installed and effective capacity. The highest recorded combined output was on 22nd May 2002 when the output was 222MW and in November 2006 the unit recorded 220MW during one evening peak.The number of units installed are three, producing a total capacity of 225 MW which is the biggest hydro in E. Africa. Number 1 was commissioned 1999 with a rated capacity of 81.5.MW. the second and third were installed in 1978 rating a capacity of 72.5MW.

-------KenGen (Kenya Electricity Generating Company)

Effects of Excess Current on the human body

Below 1 milliamperes (<1mA)
Generally not perceptible

1 milliamperes (1mA) 
Faint tingle.

5 milliamperes (5mA) 
Slight shock felt. Not painful but disturbing. Average individual can let go. Strong involuntary reactions can lead to other injuries.

6-5 milliamperes (6-5mA)
Painful shock, loss of muscular control. The freezing current or "let-go" range. Individual cannot let go, but can be thrown away from the circuit if exterior muscles are exited by the current.

Dangers of Electric Shock

The severity of injury from electrical shock depends on the amount of electrical current and the length of time the current passes through the body. For example, 1/10 of an ampere (amp) of electricity going through the body for just 2 seconds is enough to cause death. The amount of internal current a person can withstand and still be able to control the muscles of the arm and hand can be less than 10 milliamperes (milliamps or mA). Currents above 10 mA can paralyze or “freeze” muscles. When this “freezing” happens, a person is no longer able to release a tool, wire, or other object. In fact, the electrified object may be held even more tightly, resulting in longer exposure to the shocking current. For this reason, hand-held tools that give a shock can be very dangerous. If you can’t let go of the tool, current continues through your body for a longer time, which can lead to respiratory paralysis (the muscles that control breathing cannot move). You stop breathing for a period of time. People have stopped breathing when shocked with currents from voltages as low as 49 volts. Usually, it takes about 30 mA of current to cause respiratory paralysis.

Power Factor #2

Power factor in Relation to Power

Power is consumed only in resistance since neither pure inductor nor the capacitor consumes any power. The power consumed (True Power) in Inductor (L) and Capacitor (C) is zero. There is a circulating power that moves from the source to the load back and forth and does not do any useful work in the circuit. Current and voltage are in phase in a Resistance while they are 90 Degrees out of phase in (L) and (C). When current is in phase with voltage it produces active or True Power while it produces Reactive Power when 90 Degrees out of phase with voltage.

The Aswan High Dam - Egypt

Some brief statistics…
Official Name:    Aswan High Dam
Length        : 3830 m
Height        : 111 m
Width (at base):980 m base, 40 m crest
Maintained by    : Muaykensan

Reservoir information
Creates    : Lake Nasser
Capacity    : 111 km3

Power Generation Information
Turbines    : 12
Installed capacity: 2.1GW