Advantages and Disadvantages of Ad and Dc
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HSC PHYSICS > MOTORS AND GENERATORS| AC & DC
Gather secondary information to discuss the advantages and disadvantages of AC and DC generators and relate these to their use.
AC generators
Advantages
The slip rings of an AC generator have a continuous surface that allows the brushes to remain in contact with the ring’s surface. Thus the brushes in an AC generator do not wear out as fast as in a DC generator as they do not create an electric short circuit every half-turn. Therefore they required less maintenance and is more reliable that DC generators. AC’s voltage can be changed by transformers. It is more readily transformed to different voltages than DC. Because of this property, AC can travel longer distances on high voltage (low current) with minimal power loss. Transformers can step-down the voltage to the adequate amount to be used in homes and buildings.
Disadvantages
Power is lost through heat on transmission lines due to inductance and resistance which causes voltage drops. To minimise power loss, long distance transmission is run on high voltage (low current).
Applications of AC a a a a Most commercial motors are AC motors. In the 1960s, solid state diodes enabled AC to be converted to DC. AC generators (aka alternators) have replaced DC in in cars. Automotive alternators have advantages over DC generators as they use slip ring which provides an extended brush life over a split-ring commutator. Alternators allow the current to be changed to DC when needed.
DC generators
Advantages
An advantage of a DC generator is that its output can be made smoother by the arranging many coils in a regular pattern around the armature. The brushes are arranged to make contact only with the commutator bars corresponding to the coils producing the greatest emf at a particular time. The result is an output voltage that “ripples” about a mean value rather than fluctuating between zero and the maximum twice per revolution. The more
HSC PHYSICS > MOTORS AND GENERATORS| AC & DC
Gather secondary information to discuss the advantages and disadvantages of AC and DC generators and relate these to their use.
AC generators
Advantages
The slip rings of an AC generator have a continuous surface that allows the brushes to remain in contact with the ring’s surface. Thus the brushes in an AC generator do not wear out as fast as in a DC generator as they do not create an electric short circuit every half-turn. Therefore they required less maintenance and is more reliable that DC generators. AC’s voltage can be changed by transformers. It is more readily transformed to different voltages than DC. Because of this property, AC can travel longer distances on high voltage (low current) with minimal power loss. Transformers can step-down the voltage to the adequate amount to be used in homes and buildings.
Disadvantages
Power is lost through heat on transmission lines due to inductance and resistance which causes voltage drops. To minimise power loss, long distance transmission is run on high voltage (low current).
Applications of AC a a a a Most commercial motors are AC motors. In the 1960s, solid state diodes enabled AC to be converted to DC. AC generators (aka alternators) have replaced DC in in cars. Automotive alternators have advantages over DC generators as they use slip ring which provides an extended brush life over a split-ring commutator. Alternators allow the current to be changed to DC when needed.
DC generators
Advantages
An advantage of a DC generator is that its output can be made smoother by the arranging many coils in a regular pattern around the armature. The brushes are arranged to make contact only with the commutator bars corresponding to the coils producing the greatest emf at a particular time. The result is an output voltage that “ripples” about a mean value rather than fluctuating between zero and the maximum twice per revolution. The more
Bibliography: Generators for large scale power production, 2011, HSC Online, accessed 5 May 2013, Alternator, 2013, Wikipedia, accessed 5 May 2013, The "War of Currents", 2009, Write Work, accessed 5 May 2013, ERB 2013 Nikola Tesla vs Thomas Edison. Epic Rap Battles of History Season 2.,online video, 11 March, accessed 5 May 2013, “ Edison tried to discourage the use of AC by claiming the high voltage used for AC transmission made it more dangerous. He publically electrocuted animals with AC to convince the public of AC’s dangers and even convincing authorities to use AC for electric chair as punishment for prisoners. Edison tried to popularise the term “Westinghoused” as electrocution. In 1887, a prize of $US20 000 was offered to the company that could design and construct a system to generate hydro-electric power at Niagara Falls and transmit the electricity to the city of Buffalo (35km away from the falls). Westinghouse won the competition with the proposal of AC. The reason for AC winning is the ability to transmit power over long distances. By the late 1890s AC’s advantages was clear and large scale power generators was changed to distribute AC. Edison’s company merged with General Electric and began supplying AC power systems. Today, Westinghouse Electric Company and GE are two of the largest electric companies in the world.