Editing Electricity meter (section)

== History ==

The earliest commercial uses of electric energy, in the 1880s, had easily predictable usage; billing was based on the number of lamps or motors installed in a building.{{needcite|date=June 2024}}  However, as usage spread, and especially with the invention of [[AC power plugs and sockets|pluggable appliances]], it also became more variable, and the electric utilities sought a means to bill customers based on actual rather than estimated usage.

=== Direct current ===
[[file:DC Electric Meter.JPG|thumb|An Aron type DC electricity meter showing that the calibration was in charge consumed rather than energy]]

Many experimental types of meter were developed. [[Thomas Edison]] at first worked on a [[direct current]] (DC) electromechanical meter with a direct reading register, but instead developed an [[electrochemical]] metering system, which used an [[electrolytic cell]] to totalise current consumption. At periodic intervals the plates were removed and weighed, and the customer billed. The electrochemical meter was labor-intensive to read and not well received by customers.

DC meters often measured [[Electric charge|charge]] in ampere hours. Since the voltage of the supply should remain substantially constant, the reading of the meter was proportional to actual energy consumed. For example, if a meter recorded that 100&nbsp;ampere hours had been consumed on a 200-volt supply, then 20&nbsp;kilowatt-hours of energy had been supplied.

[[file:Reason electricity meter.JPG|thumb|left|A 'Reason' meter]]

An early type of electrochemical meter used in the United Kingdom was the 'Reason' meter. This consisted of a vertically mounted glass structure with a mercury reservoir at the top of the meter. As current was drawn from the supply, electrochemical action transferred the mercury to the bottom of the column. Like all other DC meters, it recorded ampere hours. Once the mercury pool was exhausted, the meter became an open circuit. It was therefore necessary for the consumer to pay for a further supply of electricity, whereupon, the supplier's agent would unlock the meter from its mounting and invert it restoring the mercury to the reservoir and the supply. In practice the consumer would get the supply company's agent in before the supply ran out and pay only for the charge consumed as read from the scale. The agent would then reset the meter to zero by inverting it.

In 1885 [[Sebastian Ziani de Ferranti|Ferranti]] offered a mercury motor meter with a register similar to gas meters; this had the advantage that the consumer could easily read the meter and verify consumption.<ref>Graeme Gooday ''The morals of measurement: accuracy, irony, and trust in late Victorian electrical practice'', Cambridge University Press, 2004 {{ISBN|0-521-43098-4}}, p 232–241</ref> The first accurate, recording electricity consumption meter was a [[direct current|DC]] meter by [[Hermann Aron]], who patented it in 1883. [[Baron Hirst|Hugo Hirst]] of the British [[General Electric Company plc|General Electric Company]] introduced it commercially into Great Britain from 1888.<ref name="Whyte, 1930" >{{cite book | title=Forty Years of Electrical Progress | last=Whyte |first=Adam Gowans | year=1930 | publisher=Ernest Benn |location=London | ref=Whyte, 1930 | pages=31,'''159''' }}</ref> Aron's meter recorded the total charge used over time, and showed it on a series of clock dials.

=== Alternating current ===

The first specimen of the [[alternating current|AC]] kilowatt-hour meter produced on the basis of Hungarian [[Ottó Bláthy]]'s patent and named after him was presented by the [[Ganz]] Works at the Frankfurt Fair in the autumn of 1889, and the first induction kilowatt-hour meter was already marketed by the factory at the end of the same year. These were the first alternating-current watt-hour meters, known by the name of Bláthy-meters.<ref>{{cite web|author=Eugenii Katz |url=http://people.clarkson.edu/~ekatz/scientists/blathy.html |title=Blathy |publisher=People.clarkson.edu |access-date=2009-08-04| archive-url = https://web.archive.org/web/20080625015707/http://people.clarkson.edu/~ekatz/scientists/blathy.html| archive-date = June 25, 2008}}</ref> The AC kilowatt hour meters used at present operate on the same principle as Bláthy's original invention.<ref name=Ricks1896>{{cite journal |last=Ricks |first=G.W.D. |title=Electricity Supply Meters |journal=Journal of the Institution of Electrical Engineers |date=March 1896 |volume=25 |number=120 |pages=57–77 |doi=10.1049/jiee-1.1896.0005 |url=https://archive.org/stream/journal06sectgoog#page/n77/mode/1up}} Student paper read on January 24, 1896 at the Students' Meeting.</ref><ref name="Volume 5. 1890">The Electrical engineer, Volume 5. (February, 1890)</ref><ref>The Electrician, Volume 50. 1923</ref><ref>Official gazette of the United States Patent Office: Volume 50. (1890)</ref> Also around 1889, [[Elihu Thomson]] of the American [[General Electric]] company developed a recording watt meter (watt-hour meter) based on an ironless commutator motor. This meter overcame the disadvantages of the electrochemical type and could operate on either alternating or direct current.<ref>W. Bernard Carlson, ''Innovation as a Social Process: Elihu Thomson and the Rise of General Electric'', Cambridge University Press, 2003 {{ISBN|0-521-53312-0}}, pages 1 and 258</ref>

In 1894 [[Oliver Shallenberger]] of the [[Westinghouse Electric Corporation]] applied the induction principle previously used <ref>U.S. Patent 388003</ref> only in AC ampere hour meters to produce a watt-hour meter of the modern electromechanical form, using an induction disk whose rotational speed was made proportional to the power in the circuit.<ref>Stephen A. Dyer (ed.) ''Survey of instrumentation and measurement''Wiley-IEEE, 2001 {{ISBN|0-471-39484-X}}, page 875</ref><ref>{{cite web|url=http://watthourmeters.com/westinghouse/shall-watt.html|title=Shallenberger Integrating Wattmeter|website=watthourmeters.com|access-date=2010-09-29|archive-date=2008-06-25|archive-url=https://web.archive.org/web/20080625032136/http://www.watthourmeters.com/westinghouse/shall-watt.html|url-status=dead}}</ref> The Bláthy meter was similar to Shallenberger and Thomson meter in that they are two-phase motor meter.<ref name=Ricks1896/> Although the induction meter would only work on alternating current, it eliminated the delicate and troublesome commutator of the Thomson design. Shallenberger fell ill and was unable to refine his initial large and heavy design, although he did also develop a polyphase version.