100 Years of Synchronized Timekeeping 2-17
Transcription
100 Years of Synchronized Timekeeping 2-17
120 Years of Synchronized Timekeeping in the USA Ken Reindel Director of Measurement Technology, NI Founder, Ken s Clock Clinic and KCC Scientific President, NAWCC Chapter 15 Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 1 What Is the NAWCC? • Founded in 1943, The National Association of Watch and Clock Collectors, Inc. (NAWCC) is a nonprofit scientific organization that serves as a unique educational, cultural, and social resource for its membership and the public at large. • Members include hobbyists, students, educators, casual collectors, and professionals in related retail and manufacturing trades. The one common bond (and main membership requirement) is a fascination with the art and science of timekeeping (horology). Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 2 What is NAWCC Chapter 15? • Chapter 15 is the local Chapter of the NAWCC. It is an active society of local participants with a common passion around Horology. • 150 members from Austin, San Antonio, Dallas, Houston and surrounding areas Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 3 What is the IEEE? • World s largest professional association • Dedicated to advancing technological innovation and excellence for the benefit of humanity • Its mission is to inspire a global community through IEEE's highly cited publications, conferences, technology standards, and professional and educational activities. Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 4 Agenda • A Brief History Lesson – – – – • From 5000BC to Present Day: Defining Time Time Standards, UTC The Naval Observatory—Astronomical Timekeeping WWVB Atomic Clocks and Cesium Atomic Clocks Earliest Synchronized Time: The Self Winding Clock (1890-1960) – – – – Henry Chester Pond Battery and Telegraph Technology The Clocks The Synchronizing Technology • The Partnership with Western Union • The Power System: The Next Step (1928-Present) – Henry Warren – The Synchronous Motor, Clock and its Successors – Examples • The Future – What is the status of NERC s experiment from July 2011? • Will the grid eliminate time correction? Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 5 Brief History of Timekeeping Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 6 Astrology vs. Horology • • A belief that the future can be told with stars has persisted for 5000 years The Zodiac: Based on the Duodecimal system; eg, divided into 12 sections – Capicorn, Aquarius, Pisces, Aires, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Saggitarius • Ptolemy of Alexandria (2 AD) first to suggest the earth was not the center of the universe – Developed extremely accurate sky maps dividing sky into minutes and seconds • • Earliest complex mechanisms were models of star motion Much can be learned of the history of Horology from the study of Astrology (and later Astronomy) http://www.praguealacarte.com/orloj/orlojLoader.html Prague Astronomical Clock ca 1380 12 Signs of Zodiac Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 7 Units of Time Measurement • Dates back to the Babylonians – Built on astrological observations • • • A day was defined by Earth s full rotation From Full Moon to Full Moon = 30 days Spring equinox to Spring equinox = 1 year – 12 Full Moons (months) in 1 year – Earliest year defined by Babylonians =360 days • 12 hours in day, 12 hours in night—Why? – Ancient Egyptian sundials • 10 + 2 Twilight hours – Night sky divided by 12 observable stars – Zodiac system • 60 min/hour: Babylonian sexagesimal astronomy – Possibly because LCD divisible by 1-6, 10, 12, 15, 20, and 30 • 60 sec/min: Obvious choice once dial divided into 60 Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 8 Earliest Clocks • 3500BC: Egyptian Obelisk – • • Structure which cast a shadow on the ground • • • • 1500BC: Egyptian Sundial 1500BC: Egyptian Pharaoh Amenhotep buried with vessel-based water clock (night clock) 1550BC to 500BC: Day/night first divided by passing of stars 500 to 300BC: Greek and Roman Mechanized water clocks 300BC to 200AD: Notion of a minute emerged 200AD: Far Eastern astronomical clocks • 1300AD: Primitive mechanical clocks begin to emerge (non water clocks) Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 9 Mechanical Clocks • • 1582: Galileo studies the characteristics of the pendulum 1656: Christiaan Huygens (Dutch) develops first mechanical clock based on pendulum – • • • • Achieved 10 seconds per day 1721: George Graham develops Dead Beat escapement and temperature compensated pendulum 1761: John Harrison develops the ship s chronometer based on lever escapement and balance wheel 1889: Siegmund Riefler develops first astronomical regulator (10ms per day accuracy) 1889 and forward: Chester Henry Pond pioneers one of the most successful synchronized time systems in history Source: http://www.nist.gov/pml/general/time/index.cfm Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 10 The Astronomical Regulator • Temperature compensated Pendulums • Finest movements, ultra-accurate • Dead Beat Escapements • Sometimes encased in vacuum • Output electrical signals used to synchronize other clocks • Accuracy in milliseconds per day Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 11 The US Naval Observatory What better place for an Astronomical Regulator? • 1830: Started out as the US Depot of Charts and Instruments, for regulation and repair of navigational chronometers and charts • 1845: Time ball installed for Washington and Potomac area use • 1854: Secretary of Navy declares this depot as the US Naval Observatory and Hydrographic Office – Timekeeping declared as one of its most critical functions – Has served as a reference for Standard Time since 1865 • Today: Synchronized to NIST by better than 100ns at any time Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 12 How did Naval Observatory tell time? • Sidereal Time deduced from position of earth relative to stars • Solar Time deduced from position of sun relative to earth • Star (or sun) positions vs. fixed earth reference – eg, noon to noon passage of sun through meridian • Time transferred to Astronomical Regulators • Falling Time Ball at noon for local customers – Washington businesses and Departing ships • Coordinated time signal transmitted on Western Union telegraph lines for 100 years from 1865 Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 13 The linked image cannot be displayed. The file may have been moved, renamed, or deleted. Verify that the link points to the correct file and location. Fun (and confusing) Time Facts Summary • Sidereal Day = 86,164.09053 seconds • Mean Solar Day ~ 87,600.002 seconds • UTC Day is 87,600 seconds – Based on the Atomic Second from TAI – Leap Second takes care of the difference • Atomic Second = 9,192,631,770 transitions of a Cesium atom – Defines the second – Basis of the UTC (Coordinated Universal Time) Source: Wikipedia Confused yet? Let s simplify things! Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 14 Coordinated Universal Time (UTC) • UTC is Coordinated Universal Time today – Primary standard for world timekeeping – Divides Time into Days, Hours, Minutes, Seconds – Successor of Greenwich Mean Time • UTC still referenced to Greenwich, England – Became official standard in 1961 • Leap second concept introduced in 1972 – Available via satellites, Network Time Protocol, WWV and WWVB – Referenced to TAI (International Atomic Time standard) offset corrected with the Leap Second • Uses – Cell phones, online services, WWVB, GPS – Air traffic control, weather, synchronized time systems – Pretty much everything Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 15 The Leap Second One small step for a clock; one giant leap for mankind1 • One second added periodically to the Day set by TAI (International Atomic Time) • Compensates for variations in earth s rotation due to tidal activity and other geophysical phenomena • Corrections made periodically – Difficult to predict for sure since it is irregular – Usually announced 8 weeks in advance of correction • • • • In 50 years up through 2011, 35 leap seconds Last one added in 12-31-2008 Seem to be fewer lately Next one predicted to be June 2012 Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 1Tom van Baak www.leapsecond.com 16 Variability in Earth s Rotation Source: http://tycho.usno.navy.mil/systime.html Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 17 WWV and WWVB • NIST Radio Station in Fort Collins, Colorado at up to 10,000 Watts – Double sideband AM • Broadcasts 24 Hours per day, 7 days per week • Operates at 5 frequencies from 2.5MHz-20MHz – Separate transmitter and antenna for each frequency • UTC time (Greenwich referenced) in both voice and coded form – Must correct from Greenwich to local time zone • Weather and geophysical updates, alerts also available • WWVB since 1956 – 60KHz – Much more accurate Source: http://www.nist.gov/pml/div688/grp40/wwv.cfm Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 18 WWVB and Atomic Clocks • So-called commercial Atomic Clocks and Atomic Watches are not at all atomic – They are radio-controlled – Broadcast from: WWVB in Fort Collins, CO – Broadcasting at 60KHz, 1 bit per second • WWVB uses UTC as a reference )))))))) Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 19 The TAI reference (Tempus Atomique Internationale) • Independent Atomic Clocks • Average of about 70 laboratories – 200 Atomic clocks in all • This sets the length of one second Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 20 The First REAL Atomic Clock • Constructed in 1949 by NBS (now NIST) • Accuracy 50 ppb (1.5 seconds per year) using µ-wave spectroscopy of ammonia – Not much better than the earth s rotation NBS Director Dr. Edward Condon and Dr. Harold Lyons with first Atomic clock Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 21 Early Cesium Clocks • The 1955 NPL (UK) Cesium clock with accuracy of 1 second in 300 years • First commercial Cesium beam tube built by R. Daly of National Company and J. Holloway of Varian Associates (1967). Went on to be most widely used Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 22 Fun Facts about Cesium • Discovered in 1860 by Robert Bunsen and Gustav Kirchoff • Alkali metal, Atomic Number 55 – – – – One electron in its outer atomic shell Melting Point 28C (liquid at near room temps) Similar to Rubidium and Potassium VERY reactive with water • Cesium 133 is most stable isotope, used in clocks Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers Modern Cesium (Atomic) Clock • Defines the Second – Duration of 9,192,631,770 cycles of radiation corresponding to the transition between two hyperfine levels of the ground state of cesium 133 • Atomic time scale is the statistical second based on a number of atomic clocks (eg, Naval Observatory Labs has 70 of them) • Accuracy 2ns per day (2 parts in 1014 ) or 1 sec in 1,400,000 years (45 sec off since dinosaur extinction!) HP/Agilent 5071A Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 24 The HP/Agilent 5071A • So easy to use, your child could set it up! Source: www.leapsecond.com Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 25 The Atomic Wristwatch Source: www.leapsecond.com Bill checks the time on his atomic wristwatch Backpack version Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 26 Synchronized Time from 1884-1966: The Self Winding Clock Company Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 27 What was the need? • Transportation Revolution – Railroad, Cable Cars 1890s • Industrial Revolution – Need coordinated time • Communications widespread – Telegraph – Telephone Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 28 Battery Technology ca. 1866-1896 Leclanche cell ca. 1866 • Used for doorbells, clocks prior to No. 6 • Patented; over 20,000 built • Wet electrolyte: very sloppy Columbia No. 6 Dry Battery ca. 1896 • National Carbon Co. of Lakewood, OH • Founded 1894 • EM Jewett and George Little • Solid electrolyte—Major breakthrough! • Powered telephone, doorbells, automobiles (ignitor), self-winding clocks, lanterns, etc. Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 29 Self Winding Clock Co. Wet Cell $180 on Ebay Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 30 Chester Henry Pond • Personal friend of Thomas Edison – Witnessed operation of first light bulb • Prolific Inventor; interested in telegraphs, clocks, application of electromagnets and electricity • Founded the Self Winding Clock Co. • Pond (and other engineers at SWCC) developed: – Solenoid-based adjuster for synchronizing clocks – Winding Motor for early battery operated clocks Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 31 Chester H. Pond Patents Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 32 The Self Winding Clock Company • Primary business was manufacture and leasing of self winding clocks – Used in businesses, schools, transportation, financial institutions, etc. • Appear to have adapted movements manufactured by Seth Thomas – Probably licensed to ST – May have bought ST out of equipment to make parts later in history (not clear) • Movements were very high quality with synchronization capability built in (optional) • About 600 SWCC clocks migrated to the London Underground – American Engineers brought in by Charles Tyson Yerkes specified SWCC – Purchased from 1905-1929 Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 33 Example SWCC Movements Rotary Motor: 1880s to early 1900s Style A Style B Style C 34 The Rotary Motor Brushes (3) Commutator Electromagnets (3) Rotor Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 35 Example SWCC Movements The Style F Vibrating Motor: 1892 to 1960s Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 36 The Vibrating Motor Banking Springs (2) Contacts (redundant) Armature Electromagnet 37 SWCC Chime Clock Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 38 Western Union • 1830: Joseph Henry transmitted first signal over 1 mile of wire • 1838: Samuel Morse demonstrated practical communication system • 1843: Congress funded 40 mile wire, Washington to Baltimore • 1851: Western Union formed – New York and Mississippi Valley Printing Telegraph Company – Dispatching trains via telegraph – Changed name to Western Union in 1856 • 1861: First US transcontinental telegraph lines – Mainly along railroad rights of way • • • • • 1889-1963: Joined forces with Self Winding Clock Company 1914: First commercial charge card introduced 1933: First Singing Telegram 1974: First commercial satellite introduced by WU Today: Primary business money transfers Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 39 SWCC and Western Union 1889-1963 • Entered into agreement in 1889 – Transmission of time signals and maintenance of clocks – Cost to customer was $1.25-2.00 per month • 1940: 100,000 subscribers to the service – Most subscribers had multiple clocks including both masters and slaves – Fell off after that as other methods of time synchronization emerged Western Union Master Clock Slave Clocks Naval Observatory Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 40 Synchronized Time for the Masses • Unfortunately the SWCC + WU solution was simply too expensive for the masses • Henry Warren realized that a more commercially viable method was needed Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 41 Worldwide Line Frequencies • Early AC frequencies were anywhere from 16.666Hz to 133Hz – 25Hz at Niagra Falls—not good for lighting • Parts of Canada continued 25Hz until 1948 – London in 1918 had 10 different frequencies – Some cities in Germany, Switzerland, Italy and other locations were 40Hz, before standardizing to 50Hz from 1915-1946 – Much of California used 50Hz until 1948 – Western Japan 60Hz, Eastern Japan 50Hz • Still the case today! • USA established 60Hz as the standard in the 1920s but there were exceptions Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 42 Henry Warren • • • • Born in 1872, lived in Newton Centre, Mass Enjoyed working with tools from an early age MIT BSEE Graduate in 1894 Moved to Ashland, Mass in 1904 – This is where Henry Warren developed 135 patentable inventions • • • • Developed the AC synchronous motor used in all electric clocks Developed his Master Clock for regulating line frequency in 1916 GE bought half interest in the synchronous motor in 1917 Henry Warren decided on the trade name Telechron for his products in 1923 – Telechron is Greek for Time from a Distance Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers Patent 1,283,435 43 Warren Telechron Clock Motors Source: www.billsclockworks.com Type B Motor Patents Type A Motor Type B Motor Capsule A Look Inside B Rotor Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 44 Warren Telechron Clock Motors 2 Source: www.billsclockworks.com F Rotor H Rotor Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 45 Synchronous Motor—Theory Analyzing Henry Warren s Patent • Rotating magnetic field – • Shading 2 of the 4 poles Rotor with ability to be magnetized – Called Remanence (hysteresis) – Dimensions, shape fairly critical – Warren used hard steel • Big gap between rotor and poles – Prevent stray lines of force from breaking synchronism Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 46 Warren Type A Master Clock By 1947 Warren masters regulated 95% of the power grid in the USA Type A Master Clock Type A Movement Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 47 Type B Master Clock Less accurate than Type A • Very clever design • Very attractive clock • Small dial indicates time from pendulum movement • Movement uses differential gearing • Large indicator is difference between pendulum clock and motor-driven clock • Error indicates how much generator should be sped up or slowed down • Do not run clock with pendulum stopped and clock plugged in – Will snap mainspring Type B Master Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 48 Interesting Telechron Clocks Source: www.telechron.net/main. Telechron Range Timer Model 3T14 HMI Telechron 355 Cathedral (pre-1930) Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 49 More Interesting Telechron Clocks 455 The Radio (pre-1930) 661 The Concord (pre-1930) Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 50 Other Electric Clock Manufacturers Hammond Hammond Polo Skyscraper Gregory Postal Telegraph Wall Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 51 How stable is AC line frequency in USA today? Bottom Line: It always averages out to near perfect. From www.leapsecond.com 52 How accurate will AC line frequency in USA be in the future? • Proposed change: Discontinue time error corrections (TEC) • NAESB and NERC activity – Some proposals to tighten regulation 2000-2005 – Superseded by others to eliminate it entirely 2005+ • Three networks: Eastern, Western, ERCOT – Anecdotal indication that Eastern will be affected first, ERCOT last if at all But when will it occur? Ken s Clock Clinic Clock Restorations, Vintage Dry Cells, Synchronizers 53 The Case to Eliminate TEC From 2005 NERC study WEQBPS–004-000 1. There is no clear reliability reason to perform Time Error Correction. 2. Discontinuing Time Error Correction would reduce costs including maintenance of software, training and implementation of the TEC procedures. 3. The elimination of the present Time Error Correction procedure would improve reliability as measured by the variability of interconnection frequency. 4. Based on study data from July 2005 Time Error Correction was responsible for about half of the frequency control failures (absolute line frequency falling out of spec) The only reason cited to maintain it is for clocks! 54