EE 202L Class #6
Early Electric Power Text Historical Notes
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.
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.
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,...
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.
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
Commercial Arc-Lamp Applications Arc lamps are bright! - typically 1200-4000 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)
Municipal Arc-Lamp Applications Demonstration: Cleveland, OH Monumental Park (1879) 12 2000-Candlepower Lamps Examples: 1880 Wabash, IN 3 Lamps 9000 Candlepower New York, NY Broadway
Municipal Arc-Lamp Towers??? San Jose, 1881 237 6 x 4000 cp. Paris, 1889 1052 Tower Los Angeles, 1882 150 Arc-Lamp Pole
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.
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)
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 1878. Replace gas lighting with electric lighting and subdivide the light. Edison Electric Light Company - $300,000 (October 1878)
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
Edison Incandescent Lamp Filament Design High Resistance Long Lasting Pt Carbonized Bamboo Vacuum Technology -6 10 Atmosphere Rapid Evacuation Filament Support Glass Bulb Seals Socket Optimum Line Voltage = 110 V 16-candlepower Standard 1880 1888
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
Electrochemical Metering Edison Electric Meter
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
Pearl Street Station 1880 - New York Edison Electric Illuminating Company 4 September 1882 - Station Complete
Pearl Street Station Paris Electrical Exhibition (1881) Coal Fired Six 27-Ton Jumbo Dynamos 600 kw 7200-Lamp Capacity Decommissioned in 1895
Feeder and Main Distribution System Modest Parallel-Connected Feeders Extensive Mains
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
Limited Range of Distribution Fixed dc voltage x i R t + v + Maximum range limited by
Rapid Growth Short-Range Generating Stations Factories, Stores, Hotels, Residences, Central Stations,... Isolated Edison Edison Edison Other Plants Lamps Plants Lamps Lamps 1881 5122 1882 153 29,192 12 1883 64,856 1884 98,020 1885 520 132,875 1886 702 181,463 58 149,900 84,600 Association of Edison Illuminating Companies
Financial Consolidations A. Bright, The Electric Lamp Industry (1949)
Literary Parallels (L. Frank Baum) Columbian Exposition, Chicago, 1893 Emerald City, Oz, 1939 Thomas Edison The Wizard
Enter George Westinghouse 1880 - Westinghouse (air-brake industrialist) visits New York and notes the distance limitations of the Edison dc distribution system. Transformer (ac voltages) + i i 1 2 + v 1 v 2-1 : N - 1882 - L. Gaulard and J. Gibbs 1885 - W. Stanley (Westinghouse, improved design) 1885 - C. Zipernowski, M. Deri, and O. Blathy (improved design) Edison not interested.
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).
Westinghouse Poised for Competition A. Bright, The Electric Lamp Industry (1949)
1888 - 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)
1888 - 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
1888 - 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
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).
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.
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
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
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!
General Electric A. Bright, The Electric Lamp Industry (1949)
ac Triumphant ac Power Generation Must be Synchronous (in phase)
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
New GE Talent... Charles Steinmetz Originally with Thomson-Houston Subsequently with General Electric Founder of ac Circuit Theory
Single-Phase Distribution System San Antonio Canyon to Pomona, CA
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)
Three-Phase Distribution System Mill Creek to Mentone, CA (Ice Plant) --- General Electric
Why Three Phase? Balanced Loads... Three Wires! No Return Needed
Commercial Three-Phase ac 480 + V A + 277 = 480 p 3 - Neutral 480/277 Lighting - V B V C 208 + V A + 120 = 208 p 3 - Neutral 208/120 Line Voltages - V B V C
Residential ac + + 2400-120 - + 120-2400 V from one phase Two Sets of Line Voltage (120 V) 240 V for hot water heater, oven, etc.
ac Frequency 133.3 Hz - Early choice 16.66 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
Mechanicville Generating Station
Residual dc Systems New York Subway - Rotary Converter