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TODAY IN HISTORY

    MOUNT RUSHMORE
    October 31, 1941 - Keystone, S.D., U.S.A.

    Work on Mount Rushmore finally ended with the monumental heads of four U.S. presidents - Washington, Jefferson, Lincoln, and Theodore Roosevelt - carved on the face of a mountain near Keystone, S.D. It was dedicated 3 Mar 1933 and work had been continued by Gutzon Borglum's son James after his father (1867-1941), the project's sculptor for 14 years since 10 Aug 1927, died eight months earlier. The carved faces are 60-70 feet tall, and visible for 60 mi (100 km). Gutzon Borglum's ambitious original design was left incomplete; work ceased when funds ran out. Since then, no additional carving has been done, nor is planned, other than maintenance. In its present form it stands as the largest such sculpture in existence.

    CLONED ANIMAL MEAT
    October 31, 2003 - U.S.A.

    The U.S. Food and Drug adminstration released a summary of a draft report concluding that cloned farm animals and their offspring pose little scientific risk to the food supply. This could eventually lead to products derived from clones or their offspring onto the nation's grocery shelves. No federal rule prohibits sale of food products derived from clones or their offspring, but producers say they are observing a voluntary moratorium. Since clones still cost about $20,000, they are unlikely to be eaten directly as food. Instead, farmers' elite cloned animals could be used as breeding stock to upgrade the genetics of entire herds. Milk from cloned cows and meat from offspring of cloned cows and pigs might be first to enter the food supply.

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  • No Man is Above the Law
    by Theodore Roosevelt

    "..."No man is above the law and no man is below it; nor do we ask any man's permission when we require him to obey it. Obedience to the law is demanded as a right; not asked as a favor."..."
  • 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...."

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  • Drug Abuse
    about Facts about Drugs

    Facts about drugs can protect against drug abuse. Legal drugs, such as alcohol and tobacco, kill more people than illegal drugs. Tobacco (smoking cigarettes) kills more people than any other drug. Illegal drugs including heroin, cannabis, ecstasy and amphetamines can have unknown or dangerous ingredients. Mixing drugs, especially with alcohol, can be fatal. Salary
    about Steve Jobs

    Steve Jobs' annual salary was $1, just enough to keep company health benefits.

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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