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    FIRST BLACK ASTRONAUT
    August 30, 1983 - United States

    Guion S. Bluford Jr. became the first black American astronaut to travel in space, aboard the third flight of the shuttle Challenger on the eighth Space Shuttle Mission. This was the first mission to launch and land at night. During 98 orbits of the Earth in 145 hours, the crew deployed the Indian National Satellite (INSAT-1B); operated the Canadian-built Remote Manipulator System with the Payload Flight Test Article; operated the Continuous Flow Electrophoresis System with live cell samples; conducted medical measurements to understand biophysiological effects on space flight. STS-8 landed on 5 Sep 1983. By 1992, Bluford had spent 688 hours on four space shuttle flights.

    LEONA HELMSLEY
    August 30, 1989 - U.S.A.

    Leona Helmsley the billionaire New York City hotel operator and real estate investor is convicted and sentenced to 16 years in prison ( Later Most charges were dropped and she served served 18 months in federal prison ) 1 count of conspiracy to defraud the United States. 3 counts of tax evasion. 3 counts of filing false personal tax returns. 10 counts of mail fraud. She is best known for a quote to a former housekeeper Elizabeth Baum when asked about her taxes. "We don't pay taxes. Only the little people pay taxes."

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  • All of us have a God in us
    by Earth Day, Kenya

    "...All of us have a God in us, and that God is the spirit that unites all life, everything that is on this planet. It must be this voice that is telling me to do something, and I am sure it'as the same voice that is speaking to everybody on this planet at least everybody who seems to be concerned about the fate of the world, the fate of this planet. Wangari Maathai-Noble Peace prize winner, Deputy Minister of Environment, founder Green Belt movement in Kenya...."
  • The Revolution
    by John Adams

    "...The Revolution was effected before the War commenced. The Revolution was in the minds and hearts of the people; a change in their religious sentiments of their duties and obligations. This radical change in the principles, opinions, sentiments, and affections of the people, was the real American Revolution...."

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  • Cancer Facts & Figures
    about Besides Lung Cancer

    Besides lung cancer, tobacco use also increases the risk for cancers of the mouth, lips, nasal cavity (nose) and sinuses, larynx (voice box), pharynx (throat), esophagus (swallowing tube), stomach, pancreas, kidney, bladder, uterus, cervix, colon/rectum, ovary (mucinous), and acute myeloid leukemia. Harvard Medical School
    about Eyesight Myth and Fact

    Myth: Staring at a computer screen all day is harmful to the eyes. Fact: Spending the day staring at a screen can tire or strain your eyes, but it will not hurt them. Make sure lighting doesn't create a glare on your screen. When spending long periods at your keyboard, take a break now and then to rest your eyes to reduce fatigue. Also, don't forget to blink. Your eyes need to stay lubricated to feel comfortable.

Types Of Switchgear :

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ARTICLE INFORMATION :

Switchboards are used in many electronic applications. Do you know what switchgear is? What do small companies use to direct power where it is needed? Large power plants use switchboards to distribution power.

ARTICLE CONTENT :

There are two systems or panels that are used to redistribute power or electric current to other equipment or circuits. One is the switchboard and the other is switchgear.

Electric switchboards are a device that directs the electricity from one source to another. It is composed of an assembly of panels. Each panel contains switches to allow electricity to be redirected.

With a switchboard, a technician is protected from possible electrocution. The switches in the board control the amount of current that goes into the switchboard. Such switches are fed from a generator which has AC frequency and load sharing controls. It also has gauges that show the frequency and synchroscope.

It is important that the amount of electric power that goes into the switchboard is equal to the electric power going. When you take a look inside the switchboard, you will see a bank of busbars.

The busbars, which are generally bare and supported by insulators, are wide strips of copper that connect to switchgear. The busbars act to allow passage of large electric current through the switchboard.

Before the switchboard is opened for maintenance, it is important to isolate the power because the busbars are bare. These active busbars are a deadly source of power. When working on live switchboards, precautionary measures are crucial. Be ready with your protective equipment such as thick rubber mats and gloves, when working with an open switchboard.

Switchboards are isolated and protected with other equipment including substations, motors, high or medium voltage distribution networks and transformers.

Switchgear are also essential a type of electrical distribution device that is used to convert incoming electrical power into several smaller voltages. Switchgear can also be used as a circuit breaker.

There are many different types of circuit breaker switchgear. Vacuum circuit switchgear have minimal arcing. The arc quenches when it is stretched to less the 2 to 3 mm. They?re frequently used in modern medium-voltage switchgear of up to 35,000 volts.

If you need to de-energizing equipment, you can use switchgear. It also clears faults downstream and comes in varied parameters, which include number of panels, electrical specifications and mounting style.

The common types of switchgear are vacuum circuit breakers, oil insulated switchgear, gas insulated switchgear, and a simple open air circuit breaker. Oil insulated switchgear depend on an oil vaporization blast through its arc.

The gas insulated switchgear stretches the arc with a magnetic field and also depends on the dielectric strength of the gas to quench the stretched arc. The open air switchgear circuit breakers use compressed air to blow out the arc. The displaced air that tries to escape thus blows out the arc.

Circuit breakers are a unique type of switchboards that interrupts fault currents. Their design is especially made for interruption of fault currents.

The Classifications of switchboards are based on the current rating, the amount of interrupting rating, by voltage class, insulating medium, construction types, operating method, type of current, interrupting type, and application.

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  • November 30, 2014Date Added :
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