Early Electric Power Text. Historical Notes. de #

Transcription

1 EE 202L Class #6

2 Early Electric Power Text Historical Notes

3 Where to Begin? 1876 Centennial Exposition Philadelphia, PA Telegraph (14 Exhibits) Telephone (Bell) Electric Alarms Dynamos Arc Lamps Electric Pen (Edison) Electric Dental Tool Charles Brush completes his first dynamo and arc-lamp system. Thomas Edison establishes an idea factory in Menlo Park, NJ that will lead to the development of an incandescent lighting system.

4 Brush Dynamo (dc Generator) U.S. Patent 189,997 (1877) Smithsonian Institution N-N and S-S field electromagnets (field lines parallel to pole faces). Disk armature with four coil pairs, open construction for air cooling. Special commutator alternately removes weakly contributing coils. Franklin Institute (Philadelphia) tests and endorses Brush design --- simple, easily maintained, strong current over a range of voltage.

5 Brush Arc Lamp U.S. Patent 203,411 (1878) Carbon electrodes touch to strike an electric arc (Fig. A). Solenoid engages a ring clutch to pull electrodes apart (Fig. B). Electromechanical feedback regulates a desired electrode gap. Continuous improvements: 1879, 1880, 1885,...

6 Series Distribution System Shunt cutout relays (1880) + R R R N Lamps v i v < v (Max) (Constant) Make R Small Series-connected dynamo field coils promote current regulation. Gradual development of 1-, 2-, 4-, 6-, 16-, and 40-lamp systems.

7 Entrenched Competition: Gas Lighting Troy, NY (Gasholder House) New York, NY (Delmonico s) Well-Capitalized Production Distribution Hardware Labor Force Applications Commercial Municipal Residential Boston, MA (Beacon Hill) Portland, ME (Morse House) Cost Safety

8 Commercial Arc-Lamp Applications Arc lamps are bright! - typically candlepower. (A 100-watt incandescent bulb produces about 125 candlepower.) Examples: (1878) Boston, MA Clothing Store 6 Lamps Philadelphia, PA Wanamaker s Department Store 20 lamps (5 x 4)

9 Municipal Arc-Lamp Applications Demonstration: Cleveland, OH Monumental Park (1879) Candlepower Lamps Examples: 1880 Wabash, IN 3 Lamps 9000 Candlepower New York, NY Broadway

10 Municipal Arc-Lamp Towers??? San Jose, x 4000 cp. Paris, Tower Los Angeles, Arc-Lamp Pole

11 Brush Central Distribution Systems Individual generators typically served business applications. Central stations typically served municipal lighting systems. New York, NY Philadelphia, PA First for-profit central station, San Francisco, CA (1879). California Electric Light Company, later part of PG&E Prospectus: The new arc light is not offered for domestic purposes, because in dwellings it is not as cheap as gas or oil and is not yet adapted to such uses.

12 Residential Arc-Lamp Applications? Major Disadvantages Too Bright Noxious, Noisy Home Generators Unlikely Who will subdivide the light? Optical Subdivision? Molera & Cebrian San Francisco, CA Sci. Am. 40, 383 (1879)

13 Enter Thomas Edison Successful telegraph inventions promote the capital investments needed for a research and development laboratory (1876). Telegraph and telephone work lead to the phonograph (1877). Lamp research begins in August Replace gas lighting with electric lighting and subdivide the light. Edison Electric Light Company - $300,000 (October 1878)

14 Parallel Distribution System! + v i + R t (Distribution System) R R R Worst-case load = Maximum Power Transfer Individual lamp control N Lamps = Resistivity of Copper L = Wire length A = Cross-sectional area of copper wires $$$ Make R Large

15 Edison Incandescent Lamp Filament Design High Resistance Long Lasting Pt Carbonized Bamboo Vacuum Technology Atmosphere Rapid Evacuation Filament Support Glass Bulb Seals Socket Optimum Line Voltage = 110 V 16-candlepower Standard

16 Edison Dynamo (dc Generator) Voltage regulation requires new dynamo technology. + v i + R t R Low-resistance Armature Powerful Field Poles Maximize Power for R fixed Make R fixed Make Long-Legged Mary Ann 1879

17 Electrochemical Metering Edison Electric Meter

18 Manufacturing Across the System 1881 Edison Electric Lamp Company Edison Machine Works Edison Shafting Company Edison Tube Company S. Bergmann & Company (Fixtures) 1882 Edison Company for Isolated Lighting Canadian Edison Mfg. Company

19 Pearl Street Station New York Edison Electric Illuminating Company 4 September Station Complete

20 Pearl Street Station Paris Electrical Exhibition (1881) Coal Fired Six 27-Ton Jumbo Dynamos 600 kw 7200-Lamp Capacity Decommissioned in 1895

21 Feeder and Main Distribution System Modest Parallel-Connected Feeders Extensive Mains

22 Two- and Three-Wire Distribution Two-Wire Ni Hot + + v i i i Ni Ground N Lamps Ni/2 A Three-Wire + + v i i i 0 Neutral N Lamps Balanced Load + + v i i i Ni/2 B

23 Limited Range of Distribution Fixed dc voltage x i R t + v + Maximum range limited by

24 Rapid Growth Short-Range Generating Stations Factories, Stores, Hotels, Residences, Central Stations,... Isolated Edison Edison Edison Other Plants Lamps Plants Lamps Lamps , , , , , ,900 84,600 Association of Edison Illuminating Companies

25 Financial Consolidations A. Bright, The Electric Lamp Industry (1949)

26 Literary Parallels (L. Frank Baum) Columbian Exposition, Chicago, 1893 Emerald City, Oz, 1939 Thomas Edison The Wizard

27 Enter George Westinghouse Westinghouse (air-brake industrialist) visits New York and notes the distance limitations of the Edison dc distribution system. Transformer (ac voltages) + i i v 1 v 2-1 : N L. Gaulard and J. Gibbs W. Stanley (Westinghouse, improved design) C. Zipernowski, M. Deri, and O. Blathy (improved design) Edison not interested.

28 500-V Primary 100-V Secondary Six transformers and a Siemens 500-V, 12-A ac generator provide demonstration ac distribution in Great Barrington, MA (1885). Stanley Transformer Westinghouse convinced. Westinghouse Electric Company formed (1886). Purchases North American rights to Gaulard and Gibbs transformer. Modifies Stanley transformer design for easy production. Acquires lighting companies (U.S. Electric, Weston Electric). Becomes Westinghouse Electric and Manufacturing Company (1889).

29 Westinghouse Poised for Competition A. Bright, The Electric Lamp Industry (1949)

30 dc vs. ac (Technical) dc System < 4000 feet Urban coverage Reliable, Safe (220 V) Parallel Generators Applications Lighting Motors Electroplating Battery charging Meter ac System > 4000 feet Suburb and rural coverage Low real-estate costs No Parallel Generators Applications Lighting No Motor! No Meter (soon resolved)

31 dc vs. ac (People) dc System Edison ac System Westinghouse Publicity, Fame Financial Backing J. P. Morgan Financial Backing Stock sales Politicians Research / Development Practical People Trial and Error Intuitive assessment Research / Development College Engineers Pre-calculated Design Mathematical assessment

32 dc vs. ac (Patents) dc System Edison General Electric ac System Westinghouse Electric Patents Develop dc patents Purchase ac patents Patents Text Develop ac patents Purchase dc patents Meanwhile... Thomson-Houston Electric Company has absorbed the Brush Electric Company and others. Mixed ac/dc portfolio Strong research and development effort

33 Battle of the Currents: First Shots... Edison Electric Light Company (1887) A Warning From the Edison Electric Light Company Thomas Edison, North American Review (1889) The Dangers of Electric Lighting Harold Brown, New York Post (1888) Proposes that New York ban voltages greater than 300 V. ac --- That damnable current Numerous published rebuttals attack Brown s credibility. Brown counterattacks (with help from Edison).

34 Harold Brown (1888) Columbia School of Mines - ac/dc demonstration on dogs 1000 V dc needed to kill 200 V ac needed to kill Challenge to Westinghouse: I therefore challenge Mr. Westinghouse to meet me in the presence of competent electrical experts and take through his body the alternating current while I take through mine a continuous current.... We will commence with 100 volts, and will gradually increase the pressure 50 volts at a time, I leading with each increase, until either one or the other has cried enough, and publicly admits his error. Westinghouse declines.

35 Agent of Death New York State seeks more humane executions --- no hanging. Physicians oppose lethal injection ac more lethal than dc ac Electric Chair William Kemmler Executed at Auburn, NY (1890) Westinghouse ac generator (supplied by Brown) Westinghousing

36 At Last, an ac Motor! Nicola Tesla First employed by Edison Moved to Westinghouse Numerous inventions Party Guy Induction Motor Rotating magnetic field Polyphase excitation

37 The Situation in 1892 Edison dc Commitment No Compromise Resentments Wandering Research Mismanagement Henry Villard (Morgan s Man) dc System Financially Inferior Merger? Thomson-Houston Acquired Edison Forced Out!

38 General Electric A. Bright, The Electric Lamp Industry (1949)

39 ac Triumphant ac Power Generation Must be Synchronous (in phase)

40 ac Power Loads can be resistive, capacitive, and inductive. ac voltage and current can be out of phase. v =ṽ cos!t i = ĩ cos (!t + ) P = ṽĩ 2 cos (1 + cos 2!t) ṽĩ 2 sin sin 2!t Instantaneous real power Watts Design for Instantaneous reactive power cos =1 Vars

41 New GE Talent... Charles Steinmetz Originally with Thomson-Houston Subsequently with General Electric Founder of ac Circuit Theory

42 Single-Phase Distribution System San Antonio Canyon to Pomona, CA

43 Two-Phase Distribution System Motors are difficult to start with single-phase ac voltage. Extra phase provides starting torque. Niagara Falls, NY Westinghouse Four wires (two per phase)

44 Three-Phase Distribution System Mill Creek to Mentone, CA (Ice Plant) --- General Electric

45 Why Three Phase? Balanced Loads... Three Wires! No Return Needed

46 Commercial Three-Phase ac V A = 480 p 3 - Neutral 480/277 Lighting - V B V C V A = 208 p 3 - Neutral 208/120 Line Voltages - V B V C

47 Residential ac V from one phase Two Sets of Line Voltage (120 V) 240 V for hot water heater, oven, etc.

48 ac Frequency Hz - Early choice Hz good for motors, bad for lighting 25-Hz Compromise - Niagara Falls, Westinghouse Westinghouse evolves to 60 Hz 40-Hz Compromise - Mechanicville, NY, General Electric 60 Hz Prevails 50 Hz in Europe (Edison AEG, Germany) Southern California Sheds 50 Hz in 1948

49 Mechanicville Generating Station

50 Residual dc Systems New York Subway - Rotary Converter