Siemens (unit)

The siemens (SI unit symbol: S) is the unit of electric conductance, electric susceptance and electric admittance in the International System of Units (SI). Conductance, susceptance, and admittance are the reciprocals of resistance, reactance, and impedance respectively; hence one siemens is equal to the reciprocal of one ohm, and is also referred to as the mho. The 14th General Conference on Weights and Measures approved the addition of the siemens as a derived unit in 1971.

The unit is named after Ernst Werner von Siemens. As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is upper case (S); the lower-case "s" is the symbol for the second. When an SI unit is spelled out in English, it should always begin with a lower-case letter (siemens), except where any word would be capitalized. In English, the same form siemens is used both for the singular and plural.

Definition

For a conducting or semiconducting element, electrical resistance R and electrical conductance G are defined as

Siemens

Siemens AG (German pronunciation: [ˈziːmɛns]) is a German multinational conglomerate company headquartered in Berlin and Munich and the largest engineering company in Europe.

The principal divisions of the company are Industry, Energy, Healthcare, and Infrastructure & Cities, which represent the main activities of the company. The company is a prominent maker of medical diagnostics equipment and its medical health-care division, which generates about 12 percent of the company's total sales, is its second-most profitable unit, after the industrial automation division. The company is a component of the Euro Stoxx 50 stock market index. Siemens and its subsidiaries employ approximately 362,000 people worldwide and reported global revenue of around €71.9 billion in 2014 according to their annual report.

History

1847 to 1901

Siemens & Halske was founded by Werner von Siemens and Johann Georg Halske on 12 October 1847. Based on the telegraph, his invention used a needle to point to the sequence of letters, instead of using Morse code. The company, then called Telegraphen-Bauanstalt von Siemens & Halske, opened its first workshop on October 12.

Siemens (disambiguation)

Siemens is a German engineering, electrical and telecommunications company conglomerate, founded by the Siemens family.

Siemens may also refer to

See also

Siemens Nexas

The Siemens Nexas are a class of electric multiple units manufactured by Siemens Transportation Systems for the suburban railway network of Melbourne, Australia between 2002 and 2005. The design of the trains was based on the Siemens Modular Metro.

History

In March 2000 M>Train ordered 62 Siemens Nexas trains to fulfill a franchise commitment to replace its fleet of Hitachi trains.

The original order was for 62 3-car sets, with an option for an additional ten 3-car sets. In December 2002 just before the first was delivered, National Express handed the M>Train franchise back to the Government of Victoria, thus the first Siemens Nexas' were delivered to the government. All passed to Connex Melbourne in April 2004. The option for ten additional trains was exercised in August 2005, with the last of these delivered in January 2006.

Siemens Rail Services was contracted to provide maintenance of the trains for a period of 15 years (subject to refranchising) at Newport Workshops. With the refranchising of the network to Metro Trains Melbourne in 2009, this maintenance arrangement was retained for an initial three-year period.