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Topic: Mercury arc rectifiers

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		There is no tendancy for an arc to strike up to the metal body, but if the metal body and cathode were at the same potential it is possible that a cathode spot may form on mercury droplets running back from the condensing chamber.
		In a mercury arc rectifier, the cathode is a pool of mercury, and the source of electrons is a bright spot (cathode spot) formed by an arc.
		To start a mercury arc rectifier an arc is struck between the cathode and an ignition electrode, and then this is maintained by excitation (or auxiliary) anodes, or by the main anodes, depending on the type of rectifier.
	www.tubecollector.org /mercuryarc.htm (1029 words)

	Mercury arc valve - Wikipedia, the free encyclopedia
		Rectifiers of this type were used in electric motor power supplies for industry, in electric railways, streetcars and diesel-electric locomotives, and in static inverter stations in electric power transmission.
		Mercury arc rectifiers were invented by Peter Cooper Hewitt in 1902 and further developed throughout the 1920s and 1930s by researchers in both Europe and North America.
		Mercury compounds are toxic, highly persistent in the environment, and present a danger to humans and the environment.
	en.wikipedia.org /wiki/Mercury_arc_rectifier (1439 words)

	249. Mercury (WHO Food Additives Series 4)
		MERCURY Mercury occurs naturally in the environment and is contributed to by human industrial activity.
		Mercury is present in both humic complexes and in the relatively unionized and stabilized form of mercuric sulfide (Wallace et al., 1971).
		After oxidation, the mercury is reduced to metallic state and the amount present estimated in the form of vapour released from the solution in a stream of nitrogen by flameless atomic absorption spectrophotometry, using the 253.7 nm line.
	www.inchem.org /documents/jecfa/jecmono/v004je02.htm (7604 words)

	Mercury in Industry
		Mercury compounds are readily absorbed through the skin on topical application and have the tendency to accumulate in the body.
		Mercury thermostat probes, also known as flame sensors or gas safety valves, are most commonly present as part of the safety valve that prevents gas flow if the pilot light is not lit.
		Mercury arc rectifiers within electrical transformers operate based on an arc between a pool of mercury and a metal anode that only allows current to pass in one direction.
	www.glrppr.org /docs/mercury_in_industry.htm (2285 words)

	Mercury Exposure
		KemI considers, however, that mercury and mercury compounds for use in analysis and research and development in medicinal diagnostics should be granted a time-limited exemption from the ban and be allowed to be marketed until 31 December 2007 and used until 31 December 2008.
		Mercury in such equipment is presumably most often dealt with legally in the waste stream but there is still a risk of the substance spreading in the working environment to the natural environment during manufacture and via the waste stream.
		Mercury is used in ignitrons or mercury-arc rectifiers whose function is to convert alternating electrical current to direct current.
	www.mercuryexposure.org /index.php?page_id=66 (16536 words)

	Mercury Arc Rectifiers
		Mercury arc rectifiers (also known as Cooper-Hewitt or Hewittic rectifiers) were extensively used to provide DC in high power applications, powers ranging from kilowatts up to a few megawatts, at voltages ranging from 110V to 30KV.
		Their operation is based on the discovery that an arc between a pool of mercury and a metal anode only allows current to pass in one direction.
		Mercury arc rectifiers have now been made totally obsolete by semiconductors, although there are a few still in service in old installations.
	www.electricstuff.co.uk /mercarc.html (1073 words)

	Waste Reduction and Proper Waste Management of Products Containing Mercury
		Mercury is found in both high- and low-voltage mercury arc rectifiers, oscillators, motor control switches, phanatrons, thyratrons, ignitions, and silent-switch thermostats and in the cathode tubes used in radios, radar and telecommunication equipment.
		Mercury thermostat probes, also known as flame sensors or gas safety valves, are usually present as part of the safety valve that prevents gas flow if the pilot light is not lit.
		Mercury is used in laboratories as a reagent and as a catalyst in such applications as tests for chemical oxygen demand (COD).
	www.p2pays.org /ref/01/00127.htm (3089 words)

	Rectifier - Wikipedia, the free encyclopedia
		When just one diode is used to rectify AC (by blocking the negative or positive portion of the waveform) the difference between the term diode and the term rectifier is merely one of usage, e.g., the term rectifier describes a diode that is being used to convert AC to DC.
		However, in a circuit with a non-center tapped transformer, four rectifiers are required instead of the one needed for half-wave rectification.
		A full wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output by reversing the negative (or positive) portions of the alternating current waveform.
	en.wikipedia.org /wiki/Rectifier (1595 words)

	mercury
		Mercury is also used in substantial quantities in electrolytic preparation of chlorine and caustic soda (chlor-alkali industry, mercury cell process; 25%), paint manufacture (12%), and dental preparations (3%).
		Mercury is concentrated in the sludges from sewage treatment by a factor of several hundred to several thousand over the levels initially present in the raw sewage.
		Mercury vapor concn in the stack gas of large coal-fired power generating stations in Ontario were found to range from 40 to 80 ug/cu m.
	www.speclab.com /elements/mercury.htm (2895 words)

	HVDC - The real meaning from Timesharetalk wikipedia (Site not responding. Last check: 2007-11-05)
		The grid controlled mercury arc valve became available for power transmission during the period 1920 to 1940.
		Mercury arc valves were common in systems designed up to 1975, but since then, HVDC systems use only solid-state devices.
		Pole 1 of this system still uses mercury arc rectifiers, one of the last such systems in the world to continue with this technology.
	www.timesharetalk.co.uk /wiki.asp?k=HVDC (3790 words)

	Diode - HvWiki
		They did essentially the same thing as a silicon diode, but were much larger (a 250 amp 3 phase mercury rectifier would about 3 meters long and almost 50cm in diameter, compared to a silicon diode that would be less that 10cm square) and more delicate.
		The easiest way to rectify an AC source would be to use a single diode in series with it, so current could only flow in one direction.
		A full wave rectifier uses 4 diodes and will reverse the polarity of the incoming AC wave for half of the incoming cycles, so all of the available power that a transformer can give is used.
	wiki.4hv.org /index.php/Diode (1510 words)

	mercurys (Site not responding. Last check: 2007-11-05)
		Most of the rectifier sub stations were located within the existing sub stations of the Midlands Electricity Corporation.
		The output from the rectifiers was taken by underground heavy duty feed cables to feeder pillars where there would be isolating links and/or perhaps a circuit breaker, before the supply was feed up a convenient traction pole and onto the overhead wires.
		We are currently looking towards a demonstration mercury arc rectifier and we are always looking for sources of D.C. switch gear - rated at 750 volt and up to 600 Amps.
	www.dwarner.com /bcmtg/mercurys.htm (361 words)

	W&H MAIN YARDS: Traction Motors
		Mercury arc rectifiers -- They glow like invaders from outer space, but they're not horribly inefficient, and believe it or not, that's one application where vacuum tube technology actually works out pretty well at high power and high voltage.
		My recollection is that the Virginian and New Haven, in the 1950's, used mercury-vapor (vacuum tubes, but with some mercury in them) rectifiers to drive DC-configured motors.
		I also recall something about the Virginian using AC motors with multiple pole fields to give 2-speed operation on AC, but have forgotten what configuration the AC motors were to give starting torque.
	www.spikesys.com /Trains/traction.html (857 words)

	Akira Nabae
		From 1951 to 1965 in the Engineering Department at the Tsurumi Works, he was engaged in research and development of mercury-arc rectifiers and their application to AC locomotives, paper mills, and steel and iron mills.
		He contributed to clarifying the relation between physical phenomena inside the mercury-arc rectifier and electrical properties determined by the external circuit, and succeeded in suppressing the probability of arc-back.
		From 1965 to 1978, he was with the Toshiba Heavy Apparatus Engineering Laboratory where he devoted himself to developing power-transistor PWM inverters and AC drive systems.
	www.ewh.ieee.org /soc/pels/Comm/Awards/Newell/nabae.html (377 words)

	Mercury arc rectifiers electrical apparatus (Site not responding. Last check: 2007-11-05)
		With so much listing from so many sources being continually reported, finding info on mercury arc rectifiers electrical apparatus consistently is very hard.
		Development in recent years include the creation of a directory of tips about mercury arc rectifiers electrical apparatus.
		We're certain you'll soon be using our web site for all your searches on content.
	www.skwe.org /mercury-arc-rectifiers-electrical-apparatus.html (590 words)

	The Virtual Mercury Arc Rectifier Museum (Site not responding. Last check: 2007-11-05)
		Perhaps you have photographs of Mercury Arc Rectifiers (especially while working) or literature relating to the subject then please email
		Use our email link here — Mercury Arc
		The Virtual Mercury Arc Rectifier Museum website is part of the Teleramics group © G.Johnson 2005
	www.tigercom.dsl.pipex.com (88 words)

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