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Topic: AC Power Transmission

	Electric power transmission - Wikipedia, the free encyclopedia
		AC power transmission is the transmission of electric power by alternating current.
		Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998.
		Therefore, the power lost is proportional to the resistance and inversely proportional to the square of the voltage.
	en.wikipedia.org /wiki/Electric_power_transmission (3035 words)

	Superconducting AC current limiter equipped with quick-recoverable trigger coils - Patent 5225956
		A superconducting AC current limiter as claimed in claim 1, wherein said first and third trigger coils are wound in a right-hand direction with respect to the core means, and also said second and fourth trigger coils are wound in a left-hand direction, whereby said trigger coil assembly is wound under non-electromagnetic induction condition.
		A superconducting AC current limiter as claimed in claim 5, wherein said third and fourth trigger coils are wounded on said current limiting coil, and said first and second trigger coils are further wound on said third and fourth trigger coils.
		As is known in an AC power transmission line, e.g., 3-phase power transmission line, when a shortcircuit or a ground fault happens to occur, a failure current will be increased up to several tens to several hundreds killoamperes, which will cause serious damages to various electric appliances connected to the transmission line.
	www.freepatentsonline.com /5225956.html (3251 words)

	Future Sustainable Living: Going Forward
		A third source of power loss is via coronal discharge but this loss is negligible compared to copper and radiative losses in AC high voltage power transmission lines.
		With AC transmission the peak voltage is 1.414 times the average voltage and so the line must be operated at a lower voltage level, equating to lower capacity.
		The radiative losses of AC lines are extremely high when they are run for long distances under oceans because the conductive salt water acts like a partially shorted secondary winding of a transformer.
	www.eskimo.com /~nanook/future/2006/07/going-forward.html (3277 words)

	Dynamic power and voltage regulator for an ac transmission line - Patent 5610501
		The real power needed to generate this injected voltage is provided by an energy storage device such as a capacitor, and preferably a converter such as a chopper is utilized between the capacitor and the converter to provide a constant dc input to the series inverter.
		Since the real power loss of a transmission line is always positive, the power supplied by the resistive compensator is also always positive and the apparatus of this invention appears to provide the line with a "negative resistance" characteristic in operation.
		The power drawn by the rectifier 19 is determined by the phase and magnitude of the inserted voltages and the current flow through the series insertion transformer 13.
	www.freepatentsonline.com /5610501.html (3683 words)

	AC Fundamentals
		AC signals are generated by (a) an AC generator or by (b) electronic function generators.
		When power is generated, it is normally AC When AC power is transmitted, it is stepped up to higher voltages because there is less power loss in transmission.
		AC voltage: the input couple may be set to DC (which does not filter out the DC signal) or to AC (which does filter out any DC signals).
	www.hcc.hawaii.edu /~sdunan/cent112/notes/05ACFundamentals (1527 words)

	Power flow on transmission lines
		The ratio of return power to forward power is therefore the (modulus of gamma) squared.
		The moral of this tale is that the length of cable connecting the generator to the load makes a critical engineering difference to the efficiency of power transmission, in cases where there is a mismatch at the load end of the cable.
		However, this will not necessarily result in the highest efficiency of power transmission from generator to load; such efficiency would only be 50% for a matched load of 50 ohms in our example, and we have seen that we can do better than that.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/powerflow.html (1176 words)

	Power Transmission (Site not responding. Last check: 2007-10-29)
		After power is generated at a generation plant, the voltage is "stepped up" by a transformer to give it the "push" to travel long distances.
		Transmission lines are usually on steel lattice towers, steel poles or double wooden poles.
		Power coming into your residence is usually 120 V or 220 V. Electrical substations perform many functions in controlling and transferring power in an electric system.
	www.ece.umr.edu /links/power/electric.htm (580 words)

	Bureau of Reclamation
		Power, first developed for building Theodore Roosevelt Dam and for pumping irrigation water, also helped pay for construction, enhanced the lives of farmers and city dwellers, and attracted new industry to the Phoenix area.
		While power output of Reclamation projects energized the war industry, it was also used to process food, light military posts, and meet needs of the civilian population in many areas.
		Power revenues are returned to the Federal Treasury to repay the cost of constructing, operating, and maintaining projects.
	www.usbr.gov /power/edu/history.html (2840 words)

	Upgrading Transmission Capacity for Wholesale Electric Power Trade
		Power transformers are used in generating stations to raise the voltage of the produced power from the generation voltage to transmission voltage; in distribution substations to reduce the voltage of the power delivered to the distribution system voltage; and elsewhere to connect together transmission systems designed at different voltages.
		The actual temperatures occurring in the transmission line equipment depend on the current, that is the rate of flow of the electrons, and also on ambient weather conditions, such as temperature, wind speed, and wind direction, because the weather effects the dissipation of the heat into the air.
		(5) Reactive power is a phenomenon associated with AC power characterized by the existence of a time difference between voltage and current variations and depends on the power dispatch and the power requirements of the system.
	www.eia.doe.gov /cneaf/pubs_html/feat_trans_capacity/w_sale.html (5896 words)

	Nikola Tesla \| TFCBooks Feedline Newsletter Articles
		Powered by lead-acid batteries and an electric drive motor, the explosives-laden vessel was designed to be maneuvered alongside a target using instructions received from a wireless remote-control transmitter and then detonated.
		A high power transmitter was developed, and one of these was used in Colorado to demonstrate wireless power transmission on a small scale.
		Nikola Tesla's AC power system made possible the harnessing of remote waterfalls and the long distance transmission of their energy to metropolitan centers.
	www.tfcbooks.com /articles/newslett.htm (1438 words)

	CONCEPTS OF ALTERNATING CURRENT
		AC AND DC Alternating current is current which constantly changes in amplitude, and which reverses direction at regular intervals.
		If a 120-volt lamp is to be supplied power from the 240-volt generator, a resistor or another 120-volt lamp must be placed in series with the 120-volt lamp to drop the extra 120 volts.
		This is not a practical solution to the power loss in the dc system since the load would then have to be operated at a dangerously high voltage.
	www.tpub.com /neets/book2/1.htm (707 words)

	IEEE History Center: Ames Hydroelectric Generating Plant, 1891
		DC electric power and other forms of power transmission had proven to be ineffective for the 2.6 mile distance of transmission.
		AC power was judged to be the only workable solution to the economic problems of the mining industry.
		The generator, for the power plant, and the motor for the mill, were identical single-phase alternators of 100 horsepower operated at 3,000 volts, 133 cycles per second - the largest manufactured at the time.
	www.ieee.com /web/aboutus/history_center/ames.html (440 words)

	What is alternating current? - a definition from Whatis.com - see also: AC
		Household utility current in most countries is AC with a frequency of 60 hertz (60 complete cycles per second), although in some countries it is 50 Hz.
		The voltage of an AC power source can be easily changed by means of a power transformer.
		High-voltage transmission is more efficient than low-voltage transmission over long distances, because the loss caused by conductor resistance decreases as the voltage increases.
	whatis.techtarget.com /definition/0,,sid9_gci213754,00.html (361 words)

	Power Electronics for Power Quality / Custom Power
		When we send ac electrical power across a transmission system, its capacity to handle power is limited by the inductance of the system.
		Role of power electronics is rapidly increasing in all aspects of electric energy i.e., generation, transmission, distribution and end use.
		In 1985, Dr. Hingorani was presented the Uno Lamm Medal by the IEEE Power Engineering Society for outstanding contributions in High Voltage Direct Current Technology, and later received the prestigious 1995 IEEE Lamme Medal for leadership and pioneering contributions to the transmission and distribution of electric power.
	www.ewh.ieee.org /r10/bombay/Narain.htm (914 words)

	The History of Energy \| The Franklin Institute's Resources for Science Learning
		The development of the camshaft and crankshaft allowed water power to be applied to tasks that required a reciprocating motion (e.g., operating trip hammers and blast furnace bellows), which revolutionized the iron industry.
		Although water power continued to be the dominant energy resource for manufacturing through much of the nineteenth century, particularly in France and the United States, steam power ultimately proved more flexible and economically efficient.
		Additionally, electric power supplanted horse-drawn and steam-powered street railways with the electric "trolley," it replaced gas for outdoor lighting, and it replaced kerosene lights and wood and coal stoves and heaters in homes.
	www.fi.edu /case_files/energy.html (2633 words)

	Electric Transmission & Distribution Research at ORNL - Transmission Systems
		As the Northeastern Power Blackout of August 14, 2003, made clear, the electric transmission system in the United States is under ever-increasing stress, threatening both reliability and commerce.
		Every region in the country is experiencing a decline in transmission capacity relative to the growth in load.
		Difficulties in obtaining right-of-way, regulatory uncertainty, and the fact that AC electric power transmission is inherently a communal asset, shared by all generators and loads, contribute to the problem.
	www.ornl.gov /sci/oetd/trans_systems.htm (381 words)

	AC (Site not responding. Last check: 2007-10-29)
		It is far from obvious by simple inspection, but for a sine wave shaped AC current, a DC current with value equal to the peak value of the AC divided by the square root of two, will provide exactly the same average power consumption.
		DC is still the choice for systems with small power requirements such as flashlights and mobile systems with large power requirements such as your car.
		A power station can supply a given amount of power with a higher current and lower voltage, or a higher voltage and correspondingly lower current.
	manta.uvi.edu /Physics/SCI3xxWeb/Electrical/AC.html (729 words)

	AC/DC Power Transmission Conference
		ACDC is a long established and highly respected international conference on AC and DC power transmission.
		There have also been changes in the marketplace, with further de-regulation and the growth of merchant transmission schemes.
		New challenges are arising from environmental, regulatory, political and social factors, which impact on the development of transmission networks.
	conferences.iee.org /acdc/welcome.htm (93 words)

	Howstuffworks "How Power Grids Work"
		Electrical power is a little bit like the air you breathe: You don't really think about it until it is missing.
		It is only during a power failure, when you walk into a dark room and instinctively hit the useless light switch, that you realize how important power is in your daily life.
		Power travels from the power plant to your house through an amazing system called the power distribution grid.
	www.howstuffworks.com /power.htm (289 words)

	TVA: Proposed 500-kv Transmission Line (Site not responding. Last check: 2007-10-29)
		The 500kV transmission line, or any active electrical conductor, will generate two fields: (1) an electric field that is proportional to the voltage at which the conductor is charged and (2) a magnetic field which is proportional to the current flowing in the conductor.
		A common misconception is that burying a transmission conductor reduces the strength of magnetic fields when compared to an overhead installation.
		Although a distribution-system power line is lower in voltage, if it’s improperly designed or installed underground it can produce a magnetic field with a higher intensity than a high-voltage overhead transmission line.
	www.tva.gov /power/projects/500kv_line/facts_qa.htm (1782 words)

	Westinghouse Flexible AC Transmission Systems (FACTS) (Site not responding. Last check: 2007-10-29)
		The Westinghouse power delivery solutions use high power semiconductors configured in a three-phase inverter to generate a precisely controlled voltage.
		These power flow controllers eliminate the need for large AC inductors and capacitors and large substation area requirements.
		The Unified Power Flow Controller is being developed by Westinghouse in conjunction with EPRI and American Electric Power (AEP), along with earlier work with the Western Area Power Administration (WAPA).
	www.ece.umr.edu /power/Energy_Course/energy/facts/facts.htm (991 words)

	Reinforcing the T&D Infrastructure
		These devices are useful in the steady-state operation of a power system, but their response time is too slow to react to contingencies or sudden changes in voltage and flow conditions.
		In this circumstance, operators have the ability to transfer power from a heavily or fully loaded line to one with spare capacity, thereby maximizing the capacity and efficiency of the transmission system.
		As utilities respond to the continuing deregulation of the industry, the effective use of transmission and distribution assets will be a critical discriminator and a key component of their long-term viability.
	tdworld.com /mag/power_reinforcing_td_infrastructure (1933 words)

	A VC: Wireless Power
		Tesla's idea was to shoot power into the ground, so that one could simply drive a stake into the ground to tap the power source.
		Tesla was the proponent of AC power transmission and AC motors.
		Jul 14, 2005 7:17:41 PM I have researched the Idea of the use of crystal radio and light for data transfer and power transfer and yes it is true the military is implementing it as we speak.
	avc.blogs.com /a_vc/2003/10/wireless_power.html (3098 words)

	Invent Now \| Hall of Fame \| Search \| Inventor Profile
		Nikola Tesla invented the induction motor with rotating magnetic field that made unit drives for machines feasible and made AC power transmission an economic necessity.
		Born in Smiljan Lika, Croatia, the son of a Serbian Orthodox clergyman, Tesla attended Joanneum, a polytechnic school in Graz and the University of Prague for two years.
		While in technical school, Tesla became convinced that commutators were unnecessary on motors; and while with the power company he built a crude motor which demonstrated the truth of his theory.
	www.invent.org /hall_of_fame/143.html (214 words)

	0005_red
		Designed to protect vital equipment from spikes, dips and outages/failure in AC power transmission, while providing clean, stable power MIS professionals depend upon.
		PES performs expert power audits and adequacy evaluation to optimize capital investment and space, while providing power advice for upgrading telephone switches and peripheral equipment.
		Innovative solutions to adapt to ever-changing needs and to plan for an increasingly unpredictable power density curve requiring scalable data center architecture for infrastructure on demand.
	www.peakenergysystems.com /services.html (284 words)

	Inventor Nikola Tesla Biography
		For a brief period he was employed by Thomas Edison, but he left that position to devote himself exclusively to experimental research and invention.
		Other AC patents were used in the Westinghouse generators at Niagara Falls.
		His motor was the solution which made long-distance energy transmission possible, due to the possibility of transforming alternating currents into high voltage for more efficient transmission and low voltage for practical use.
	www.ideafinder.com /history/inventors/tesla.htm (1321 words)

	2006 Bower Award and Prize for Achievement in Science
		A modern-age pioneer of power electronics, Narain Hingorani is considered the father of flexible alternating current transmission systems (FACTS) and custom power innovations, and a leader in high voltage direct current (HVDC).
		His developments are expected to revolutionize future alternating current (AC) power transmission and distribution systems.
		After 20 years at EPRI, five years as vice president, electrical systems division, he retired to start his own consulting business in the development of power electronics and devices, and the application of power electronics to transmission, distribution, industrial power, and marine power systems.
	sln.fi.edu /tfi/exhibits/bower/06/science.html (306 words)

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