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TODAY IN HISTORY

    DAGUERROTYPE
    February 9, 1839 - French Academy of Science

    The daguerreotype photo process was announced at the French Academy of Science. Previous photographic processes required hours of exposure, but the daguerreotype (named after its inventor Louis Daguerre) needed only a few seconds. The plate was prepared with a layer of photo-sensitive silver halide, was exposed, developed using mercury vapor, and fixed in a solution of sodium hyposulphite. The image remains delicate, and must be protected under glass against damage by touching. The daguerreotype was produced with a direct positive image, needing no intermediate negative, but thus could not yield multiple reproductions made possible by later photographic processes.

    JAPANESE NUCLEAR ACCIDENT
    February 9, 1991 - Mihama, Japan

    Japan's worst nuclear accident up to this date happened at Mihama. A pipe in the steam generator burst, leaking 55 tonnes of radioactive primary (reactor) coolant water into the secondary steam-generating circuit. Some radioactivity was released to the atmosphere and the plant's emergency core cooling system was activated. MITI reported later that the accident was caused by human error, some anti-vibration bars being wrongly installed by workers and sawn off short to make them fit. The release of radiation into the atmosphere was kept to a small amount. No deaths resulted. Various measures were taken to prevent the recurrence of the accident, including the replacement of the steam generators.

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RANDOM QUOTES

  • Until a man duplicates a blade of grass
    by Earth Day, Thomas Alva Edison Inventor

    "...Until a man duplicates a blade of grass, Nature can laugh at his so-called scientific knowledge. Remedies from chemicals will never stand in favorable comparison with the products of Nature, the living cell of a plant, the final result of the rays of the sun, the mother of all life...."
  • 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...."

RANDOM FACTS

  • 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. 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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