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Generators

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Abishek
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PostSubject: Generators Wed Feb 24, 2010 11:25 pm

Do we have to study the principle, theory, description and use of d.c generators? and can someone please give me notes on comparison of ac and dc generators(for variation of current and voltage with time)?
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kool
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PostSubject: Re: Generators Fri Feb 26, 2010 6:53 pm

Direct current or DC electric motors work for situations where speed
needs to be controlled. DC motors have a stable and continuous current.
DC motors were the first and earliest motors used. They were found,
however, to not be as good at producing power over long lengths.
Electric companies found using DC motors to generate electric did not
work because the power was lost as the electric was transmitted. Brush
DC motors use rings that conduct the current and form the magnetic drive
that powers the rotor. Brushless DC motors use a switch to produce the
magnetic drive that powers the rotor. Direct current motors are often
found in appliances around the home.
Alternating current or AC electric motors are used differently based on
what type of AC motor it is. Single phase AC motors are known as general
purpose motors. They work well in many different situations. These AC
motors work great for systems that are hard to start because they need a
lot of power up front. Three phase, also called polyphase, AC motors
are usually found in industrial settings. These motors also have high
starting power built transmit lower levels of overall power. AC power
gets its name from the fact that it alternates in power. The amount of
power given off by an AC motor is determined by the amount of power
needed to operate the system
maY THIS be helpful to u till sm extent!!!
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Abishek
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PostSubject: Re: Generators Fri Feb 26, 2010 7:12 pm

umm...i needed the notes on comparison of ac and dc GENERATORS(for variation of current and voltage with time)....btw we don't have motors right??
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kool
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PostSubject: Re: Generators Fri Feb 26, 2010 7:15 pm

ok
sorry
i thought that it is motors instead of dynamo..........
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Abishek
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PostSubject: Re: Generators Fri Feb 26, 2010 7:23 pm

np ....plz put up the notes for the comparison for ac and dc generators. We don't have motors. Smile cheers
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kool
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PostSubject: Re: Generators Fri Feb 26, 2010 7:46 pm

according to me the differences shuld be the same as that is of the ac and dc....
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SHASHANK N K
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PostSubject: Re: Generators Fri Feb 26, 2010 11:22 pm

hey dont worry on dc generator coz v dont hav it for syllabus of ISC2010
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Abishek
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PostSubject: Re: Generators Sat Feb 27, 2010 1:57 pm

i checked the syllabus and it said that we needed to knw the comparison.
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WinRrule
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PostSubject: Re: Generators Sun Feb 28, 2010 3:07 pm

The essential difference between an AC and a DC generator is the nature of the connection between the rotor coils and the external circuit.

In an AC generator, the brushes run on slip rings which maintain a constant connection between the rotating coil and the external circuit. This means that as the induced emf changes polarity with every half-turn of the coil, the voltage in the external circuit varies like a sine wave and the current alternates direction.

In a DC generator, the brushes run on a split-ring commutator which reverses the connection between the coil and the external circuit for every half-turn of the coil. This means that as the induced emf changes polarity with every half-turn of the coil, the voltage in the external circuit fluctuates between zero and a maximum while the current flows in one constant direction.
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