"250 V and at 50 Hz to 60 Hz. The other categories are typically AC applications and usually have much more restricted input ranges. A study by the Building Research Establishment in the UK states that ""The existing 230 V system is well suited to the future of electricity whether through design or Darwinian processes. Any current perceived weakness is generally a result of cost reduction and market forces rather than any fundamental technical difficulties. Questions as to whether there are alternatives to the existing 230 V AC system are often overshadowed by legacy issues, the future smart agenda and"
"Station. In the United Kingdom, the Network Rail 750 V DC electrification system in the southeast of England is supplied with power from an extensive 33 kV power distribution network. Traction current lines are used to power the railway systems of countries which use alternating current of a lower frequency than the public supply. This is typically the case in the German-speaking countries of Europe. For example, 16.7 Hz AC is used in Germany, Austria and Switzerland. A specific example is the Mariazeller narrow gauge railway in Austria, operating with single phase AC with a frequency of 25 Hz, which"
"Utility frequency The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of the oscillations of alternating current (AC) in an electric power grid transmitted from a power station to the end-user. In large parts of the world this is 50 Hz, although in the Americas and parts of Asia it is typically 60 Hz. Current usage by country or region is given in the list of mains power around the world. During the development of commercial electric power systems in the late 19th and early 20th centuries, many different frequencies (and voltages)"
"unnecessary by high power locomotive rectifiers that can convert any AC frequency to DC: first the mercury-arc rectifier and then the semiconductor rectifier. Some AC railways have been converted to standard grid frequencies, but low frequencies are still widely used due to large sunken equipment costs. Five European countries, Germany, Austria, Switzerland, Norway and Sweden, have standardized on 15 kV Hz (the 50 Hz mains frequency divided by three) single-phase AC. On 16 October 1995, Germany, Austria and Switzerland changed from Hz to 16.7 Hz which is no longer exactly one-third of the grid frequency. This solved overheating problems with"
"most common frequency was 133⅓ Hz. The rotation speed of induction generators and motors, the efficiency of transformers, and flickering of carbon arc lamps all played a role in frequency setting. Around 1893 the Westinghouse Electric Company in the United States and AEG in Germany decided to standardize their generation equipment on 60 Hz and 50 Hz respectively, eventually leading to most of the world being supplied at one of these two frequencies. Today most 60 Hz systems deliver nominal 120/240 V, and most 50 Hz nominally 230 V. The significant exceptions are in Brazil, which has a synchronized 60"
"Heinrich Hertz Heinrich Rudolf Hertz (; ; 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves theorized by James Clerk Maxwell's electromagnetic theory of light. The unit of frequencycycle per secondwas named the ""hertz"" in his honor. Heinrich Rudolf Hertz was born in 1857 in Hamburg, then a sovereign state of the German Confederation, into a prosperous and cultured Hanseatic family. His father Gustav Ferdinand Hertz (originally named David Gustav Hertz) (1827–1914) was a barrister and later a senator. His mother was Anna Elisabeth Pfefferkorn. Hertz's father converted"
"the electric current. The first system used was 1500 V d.c., commissioned in 1956, following the commissioning of the main line from London to Shenfield in 1949. This was to replace an intensive steam service. In the 1960s the line was converted to 6.25 kV, 50 Hz as part of the decision by the British Transport Commission to adopt 25 kV 50 Hz electrification as the standard system rather than 1500 V d.c. electrification. The line did not immediately use 25 kV due to problems with clearances under bridges. In 1979, it was converted for a second time to 25"
"Hertz The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (10 Hz, kHz), megahertz (10 Hz, MHz), gigahertz (10 Hz, GHz), terahertz (10 Hz, THz), petahertz (10 Hz, PHz), and exahertz (10 Hz, EHz). Some of the unit's most common uses are in the description of sine waves and musical tones, particularly those used in radio- and"
"say, hairdriers, are available; travel adapters usually include plug-end adapters for the different standards used in different countries. A transformer would be used for higher power. Transformers do not change the frequency of electricity; in many regions with 100–120 V, electricity is supplied at 60 Hz, and 210–240 V regions tend to use 50 Hz. This may affect operation of devices which depend on mains frequency (some audio turntables and mains-only electric clocks, etc., although modern equipment is less likely to depend upon mains frequency). Equipment with high-powered motors or internal transformers designed to operate at 60 Hz may overheat"
"manual for designers of radio equipment listed the following now obsolete frequencies as in use. Many of these regions also had 50 cycle, 60 cycle or direct current supplies. Frequencies in use in 1946 (as well as 50 Hz and 60 Hz) Where regions are marked (*), this is the only utility frequency shown for that region. Other power frequencies are still used. Germany, Austria, Switzerland, Sweden and Norway use traction power networks for railways, distributing single-phase AC at 16⅔ Hz or 16.7 Hz. A frequency of 25 Hz is used for the Austrian Mariazell Railway, as well as Amtrak"
"five units were operating at full load. The pressure of the steam used in the station was at 275 psi, and at a temperature of 700 degrees Fahrenheit; this was the highest steam pressure adopted by any electric supply company in England. The station used metal clad switchgear. When the UK's national grid distribution system was brought into use in 1932, the station in common with all other NESCo-owned power stations had to be converted from the 40 hertz (Hz) frequency as used by the North Eastern grid system to the 50 Hz frequency used by the new national system."
"a geographic area can be interconnected in a grid, providing reliability and cost savings. Many different power frequencies were used in the 19th century. Very early isolated AC generating schemes used arbitrary frequencies based on convenience for steam engine, water turbine and electrical generator design. Frequencies between 16⅔ Hz and 133⅓ Hz were used on different systems. For example, the city of Coventry, England, in 1895 had a unique 87 Hz single-phase distribution system that was in use until 1906. The proliferation of frequencies grew out of the rapid development of electrical machines in the period 1880 through 1900. In"
"at 750 volts DC as Phase 2 of British Rail’s Kent Coast Electrification Scheme. Some electric trains began running in 1961, with the full service beginning with the Summer timetable on 18 June 1962. There were 2 trains per hour (tph) off-peak, mostly from Charing Cross to Ramsgate, until May 1982, when the service was reduced to 1 tph off-peak (2 tph in the peaks). the typical off-peak service from the station is one train per hour to , which continue onwards to and the Medway Towns, and ultimately to London St Pancras, and one train per hour to London"
"Charles Hesterman Merz Charles Hesterman Merz (5 October 1874 – 14 or 15 October 1940) was a British electrical engineer who pioneered the use of high-voltage three-phase AC power distribution in the United Kingdom, building a system in the North East of England in the early 20th century that became the model for the country's National Grid. Merz was the eldest son of industrial chemist John Theodore Merz (a Quaker from Germany) and Alice Mary Richardson, a sister of John Wigham Richardson the Tyneside ship builder. He was born in Newcastle upon Tyne and attended Bootham School, York. He attended"
"V (CENELEC Harmonization Document HD 472 S1:1988). The standard nominal supply voltage in domestic single-phase 50 Hz installations in the UK is still 240 V AC (RMS), but since 1 January 1995 (Electricity Supply Regulations, SI 1994, No. 3021) this has an asymmetric voltage tolerance of (216.2–253.0 V), which covers the same voltage range as continental 220 V supplies to the new unified 230 V standard. This was supposed to be widened to 230 V ±10% (207–253 V), but the time of this change has been put back repeatedly and as of December 2012 there is no definitive date. The"
"German physicist Heinrich Hertz. One hertz means that an event repeats once per second. If a TV has a refresh rate of 1 hertz the TV's screen will change (or refresh) its picture once a second. A previous name for this unit was cycles per second (cps). The SI unit for period is the second. A traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm. 60 rpm equals one hertz. As a matter of convenience, longer and slower waves, such as ocean surface waves, tend to be described by wave period rather"
"by his life's work, on its home page. Heinrich Hertz Heinrich Rudolf Hertz (; ; 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves theorized by James Clerk Maxwell's electromagnetic theory of light. The unit of frequencycycle per secondwas named the ""hertz"" in his honor. Heinrich Rudolf Hertz was born in 1857 in Hamburg, then a sovereign state of the German Confederation, into a prosperous and cultured Hanseatic family. His father Gustav Ferdinand Hertz (originally named David Gustav Hertz) (1827–1914) was a barrister and later a senator. His"
"cold stores, large water pumping stations, can offer to the UK National Grid. These contractors have frequency sensitive relays fitted to the incoming breakers, and these disconnect the load if the system frequency falls beyond a pre-set figure (49.7 Hz). These loads are shed for a contracted period of at least 30 minutes. Within this period Standing Reserve (Reserve Service) diesels of similar capacity (i.e., around 660 MW total) start up, and enable the Frequency Service loads to be re-connected and the relays re-armed. Frequency Service is designed to cope with the loss of two 660 MW sets in quick"
"stations. This covers a few hours of operation giving time for market contracts to be established to cover longer term balancing. Frequency-response reserves act to keep the system's AC frequency within ±1% of 50 Hz, except in exceptional circumstances. These are used on a second by second basis to either lower the demand or to provide extra generation. Reserve services are a group of services each acting within different response times: These reserves are sized according to three factors: The English and Welsh parts of the National Grid are controlled from the National Grid Control Centre which is located in"
"with 40 Hz electrical systems which were maintained until too uneconomic to continue. Although frequencies near 40 Hz found much commercial use, these were bypassed by standardized frequencies of 25, 50 and 60 Hz preferred by higher volume equipment manufacturers. The Ganz Company of Hungary had standardized on 5000 alternations per minute (41 Hz) for their products, so Ganz clients had 41 Hz systems that in some cases ran for many years. In the early days of electrification, so many frequencies were used that no one value prevailed (London in 1918 had ten different frequencies). As the 20th century continued,"
"daughter Mathilde Carmen Hertz was a well-known biologist and comparative psychologist. Hertz's grandnephew Hermann Gerhard Hertz, professor at the University of Karlsruhe, was a pioneer of NMR-spectroscopy and in 1995 published Hertz's laboratory notes. The SI unit ""hertz"" (Hz) was established in his honor by the International Electrotechnical Commission in 1930 for frequency, an expression of the number of times that a repeated event occurs per second. It was adopted by the CGPM (Conférence générale des poids et mesures) in 1960, officially replacing the previous name, ""cycles per second"" (cps). In 1928 the Heinrich-Hertz Institute for Oscillation Research was founded"
"V (always expressed as root-mean-square voltage). The two commonly used frequencies are 50 Hz and 60 Hz. Single-phase or three-phase power is most commonly used today, although two-phase systems were used early in the 20th century. Foreign enclaves, such as large industrial plants or overseas military bases, may have a different standard voltage or frequency from the surrounding areas. Some city areas may use standards different from that of the surrounding countryside (e.g. in Libya). Regions in an effective state of anarchy may have no central electrical authority, with electric power provided by incompatible private sources. Many other combinations of"
"National Grid Company (who operated the UK electricity grid system) to deal with short-term peaks in demand. Such peaks typically arise during the winter months, where evening demand is higher due to lighting and heating requirements. A further facility provided to the National Grid Company by the OCGTs was one of system protection. They would start automatically should the system frequency (50.0 Hz in the UK) fall to 49.6 Hz, which would indicate that the supply from generation was not sufficient to meet the demand. The National Grid Company are obliged to ensure that there is enough operating reserve available"
"low impedance path allows the maximum amount of fault current, causing the overcurrent protection device (breakers, fuses) to trip or burn out as quickly as possible, bringing the electrical system to a safe state. All bond wires are bonded to ground at the main service panel, as is the neutral/identified conductor if present. The frequency of the electrical system varies by country and sometimes within a country; most electric power is generated at either 50 or 60 Hertz. Some countries have a mixture of 50 Hz and 60 Hz supplies, notably electricity power transmission in Japan. A low frequency eases"
"kW ERP), BBC Radio Kent on 96.7 MHz (4.4 kW ERP) and KMFM West Kent on 101.6 MHz (0.2 kW ERP). (There are two prominent towers in the south of Greater London, Croydon and Crystal Palace, which provide a medium power (4 kW ERP) relay of the national radio channels, in addition to local stations). Wrotham was the first station in the UK to broadcast on VHF/FM, with three services beginning officially on 2 May 1955. It broadcast the Home Service (now Radio 4), the Third Programme (now Radio 3) and the Light Programme (now Radio 2). The frequencies it"
"40 Hz systems were built. The Lauffen-Frankfurt demonstration used 40 Hz to transmit power 175 km in 1891. A large interconnected 40 Hz network existed in north-east England (the Newcastle-upon-Tyne Electric Supply Company, NESCO) until the advent of the National Grid (UK) in the late 1920s, and projects in Italy used 42 Hz. The oldest continuously operating commercial hydroelectric power station in the United States, Mechanicville Hydroelectric Plant, still produces electric power at 40 Hz and supplies power to the local 60 Hz transmission system through frequency changers. Industrial plants and mines in North America and Australia sometimes were built"
"an AC appliance or socket, the hum is also inadvertently recorded. The peaks of the hum repeat every AC cycle (every (1000/50) round 2 ms for 50 Hz AC, or every (1000/60) round 2 ms for 60 Hz AC). Any edit of the audio that is not a multiplication of the time between the peaks will distort the regularity, introducing a phase shift. A continuous wavelet transform analysis will show discontinuities that may tell if the audio has been cut. Utility frequency The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of"
"and SEPTA's traction power systems in the United States. Other AC railway systems are energized at the local commercial power frequency, 50 Hz or 60 Hz. Traction power may be derived from commercial power supplies by frequency converters, or in some cases may be produced by dedicated traction powerstations. In the 19th Century, frequencies as low as 8 Hz were contemplated for operation of electric railways with commutator motors. Some outlets in trains carry the correct voltage, but using the original train network frequency like 16⅔ Hz or 16.7 Hz. Power frequencies as high as 400 Hz are used in"
"of opening because of drivers' difficulty setting their radios to the correct frequency (88.8 MHz). Power is delivered to the locomotives via an overhead line (catenary) at . All tunnel services run on electricity, shared equally from English and French sources. There are two sub-stations fed at 400 kV at each terminal, but in an emergency the tunnel's lighting (about 20,000 light fittings) and plant can be powered solely from either England or France. The traditional railway south of London uses a 750 V DC third rail to deliver electricity, but since the opening of High Speed 1 there is"
"more power was produced at 60 Hz (North America) or 50 Hz (Europe and most of Asia). Standardization allowed international trade in electrical equipment. Much later, the use of standard frequencies allowed interconnection of power grids. It wasn't until after World War II with the advent of affordable electrical consumer goods that more uniform standards were enacted. In the United Kingdom, a standard frequency of 50 Hz was declared as early as 1904, but significant development continued at other frequencies. The implementation of the National Grid starting in 1926 compelled the standardization of frequencies among the many interconnected electrical service"
"aggressive. In some countries where electric locomotives or electric multiple units run on low frequency AC power, there are separate single phase traction power networks operated by the railways. Prime examples are countries in Europe (including Austria, Germany and Switzerland) which utilize the older AC technology based on 16 ""/"" Hz (Norway and Sweden also use this frequency but use conversion from the 50 Hz public supply; Sweden has a 16 ""/"" Hz traction grid but only for part of the system). High-temperature superconductors (HTS) promise to revolutionize power distribution by providing lossless transmission of electrical power. The development of"
"voltage and utility frequency were formerly used, with frequencies between 25 Hz and 133 Hz and voltages from 100 V to 250 V. Direct current (DC) has been almost completely displaced by alternating current (AC) in public power systems, but DC was used especially in some city areas to the end of the 20th century. The modern combinations of 230 V/50 Hz and 120 V/60 Hz, listed in IEC 60038, did not apply in the first few decades of the 20th century and are still not universal. Industrial plants with three-phase power will have different, higher voltages installed for large"
"high-energy, or, equivalently, massive particles, although these are not directly observable and must be inferred from their interactions with other phenomena. By convention, these are typically not expressed in hertz, but in terms of the equivalent quantum energy, which is proportional to the frequency by the factor of Planck's constant. Hertz The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed"