{"id":330,"date":"2016-02-24T23:53:19","date_gmt":"2016-02-24T23:53:19","guid":{"rendered":"http:\/\/www.edisontc.org\/ui\/?page_id=330"},"modified":"2017-03-09T22:10:53","modified_gmt":"2017-03-09T22:10:53","slug":"voltmeters","status":"publish","type":"page","link":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/","title":{"rendered":"Voltmeters"},"content":{"rendered":"<figure id=\"attachment_333\" aria-describedby=\"caption-attachment-333\" style=\"width: 700px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-333\" src=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/BrassVoltmeter800-1.jpg\" alt=\"A 1901 GE volt meter\" width=\"700\" height=\"507\" srcset=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/BrassVoltmeter800-1.jpg 700w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/BrassVoltmeter800-1-300x217.jpg 300w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><figcaption id=\"caption-attachment-333\" class=\"wp-caption-text\">A 1901 GE volt meter<\/figcaption><\/figure>\n<p><strong>The voltmeter is a key instrument in our world<\/strong> of electrical technology. They are used in everything from x-ray machines to radio transmission, computers to power utility and atmospheric science measurement to the Hubble Telescope. Voltmeters can use magnetic fields, electrostatic fields, and plasma phenomena to measure voltage. In this page we talk about <strong>PMMC<\/strong> or moving coil galvanometer type voltmeters which were the first voltmeters and dominated the industry for over 100 years until they were replaced by wide use of <a href=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/multimeters\/\">digital multimeters (DMMs).<\/a><\/p>\n<p>To see the science and engineering of the voltmeter we recommend you watch our short video below, <strong>if you saw this video at the start of Unit 1 already you can move on.<\/strong><\/p>\n<p><center><iframe loading=\"lazy\" src=\"https:\/\/www.youtube.com\/embed\/hlCHpkkmBdo?rel=0\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/center>To the right you will see a simple schematic of the voltmeter reading the DC voltage of a circuit that consists of a battery and lightbulb. The way the voltmeter is positioned in the circuit is different from the ammeter. The voltmeter works by measuring the potential difference between two points. <a href=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/ammeters\/\">The ammeter<\/a> on the other hand is positioned <strong>in series<\/strong> with the circuit.<\/p>\n<figure id=\"attachment_902\" aria-describedby=\"caption-attachment-902\" style=\"width: 300px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-902 size-medium\" src=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2-300x180.png\" alt=\"\" width=\"300\" height=\"180\" srcset=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2-300x180.png 300w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2-768x461.png 768w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2-1024x614.png 1024w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2-24x14.png 24w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2-36x22.png 36w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2-48x29.png 48w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/SimpleDCvoltSchematic2.png 1500w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-902\" class=\"wp-caption-text\">Voltmeter placement in a DC circuit. The voltmeter measures current (marked by the &#8220;A&#8221; for ammeter) but has a resistor in parallel.<\/figcaption><\/figure>\n<p>The voltmeter is built on the equation:<\/p>\n<p><strong>voltage = current x resistance<\/strong><\/p>\n<p>Voltmeters were really measuring the current through a resistor. More sensitive ammeters led to the voltmeter. The Ammeter was developed first because it was easier to measure higher current. In the voltmeter we need to be able to measure the small sample of current.<\/p>\n<p><strong>Ability to measure milli and microamps leads to the voltmeter:<\/strong><\/p>\n<figure id=\"attachment_336\" aria-describedby=\"caption-attachment-336\" style=\"width: 191px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltmeterPatentShall1888-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-336 size-medium\" src=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltmeterPatentShall1888-1-191x300.jpg\" alt=\"VoltmeterPatentShall1888\" width=\"191\" height=\"300\" srcset=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltmeterPatentShall1888-1-191x300.jpg 191w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltmeterPatentShall1888-1.jpg 400w\" sizes=\"auto, (max-width: 191px) 100vw, 191px\" \/><\/a><figcaption id=\"caption-attachment-336\" class=\"wp-caption-text\">Click on the image to magnify. This is an early multi-meter: it can measure volts or amps.<\/figcaption><\/figure>\n<p>Edward Weston revolutionized the field of instrumentation when he developed the first portable electric meters and a reliable <strong>PMMC<\/strong> (permanent magnet moving coil instrument).<\/p>\n<p>Stable permanent magnets and consistent resistor materials are required for accurate voltmeters. Westin&#8217;s <a href=\"https:\/\/en.wikipedia.org\/wiki\/Manganin\"><strong>Manganin<\/strong><\/a> alloy enabled stable resistors for use in voltmeters and ammeters. Manganin is made from 86% copper, 2% nickel, and 12% manganese.<\/p>\n<p>From a science perspective Weston found that metals can have a negative <a href=\"https:\/\/en.wikipedia.org\/wiki\/Temperature_coefficient\">temperature coefficient<\/a> of resistance.<\/p>\n<p>Before the 1870s meters were fragile lab instruments not entirely useful for testing systems. Before the 1870s most electrical installations were for the telegraph where there was not a need for regular measurements. <a href=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/galvanometers\/\">Mirror galvanometers<\/a> were used to help set up telegraphs. <a name=\"early\"><\/a><a name=\"early\"><\/a>Westinghouse led many of the innovations in voltmeter design with AC pioneer <a href=\"http:\/\/pabook.libraries.psu.edu\/palitmap\/ElectricMeter.html\">Oliver Shallenberger<\/a> on the team. Philip Lange and Shallenberger took the galvanometers of the time and added the needed resistors that converted them from ammeter to voltmeter. They redesigned the meters to work with Tesla&#8217;s 2-phase system, and later <a href=\"http:\/\/www.edisontechcenter.org\/AC-PowerHistory.html\">Dobrovolsky&#8217;s 3-phase system<\/a> which ended up being today&#8217;s standard.<a name=\"standard\"><\/a><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-334 alignright\" src=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/GEmeter600-300x285.jpg\" alt=\"GEmeter600\" width=\"300\" height=\"285\" srcset=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/GEmeter600-300x285.jpg 300w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/GEmeter600.jpg 632w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/>The standard volt and ammeters through most of electrical age were magnetically driven and use a robust &#8220;can&#8221; design with permanent magnet.<\/p>\n<p><a name=\"standard\"><\/a> The industry standard of voltmeter for many decades was developed in 1886 by chemist and engineer Edward Weston in New Jersey. Weston&#8217;s innovation included a stable permanent magnet and his development of a special <a href=\"https:\/\/en.wikipedia.org\/wiki\/Manganin\">Manganin<\/a> material. See our page on <a href=\"http:\/\/www.edisontc.org\/ui\/unit-i\/ammeters\/\">ammeters<\/a> to read more about the design since ammeters and voltmeters were very close.<\/p>\n<figure id=\"attachment_335\" aria-describedby=\"caption-attachment-335\" style=\"width: 800px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-335 size-full\" src=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltMeterDonut800.jpg\" alt=\"Historic Voltmeter\" width=\"800\" height=\"467\" srcset=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltMeterDonut800.jpg 800w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltMeterDonut800-300x175.jpg 300w, http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/VoltMeterDonut800-768x448.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-335\" class=\"wp-caption-text\">A 1901 General Electric voltmeter<\/figcaption><\/figure>\n<table width=\"100%\">\n<tbody>\n<tr>\n<td>\n<div style=\"background: grey; float: left; text-align: center; line-height: 100px; width: 40%; margin: 10px; padding: 10px; box-shadow: 5px 5px 10px #000; min-height: 100px;\"><a style=\"text-decoration: none;\" href=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/watt-hour-meters-history\/\">Back<\/a><\/div>\n<div style=\"background: grey; float: right; text-align: center; line-height: 100px; width: 40%; margin: 10px; padding: 10px; box-shadow: 5px 5px 10px #000; min-height: 100px;\"><a style=\"text-decoration: none;\" href=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/inventors-of-the-voltmeter\/\">Next<\/a><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Further reading:<\/p>\n<p><a href=\"http:\/\/www.electrical4u.com\/permanent-magnet-moving-coil-instrument\/\">The PMMC<\/a><\/p>\n<p><a href=\"https:\/\/en.wikipedia.org\/wiki\/Edward_Weston_(chemist)\">Edward Weston<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The voltmeter is a key instrument in our world of electrical technology. They are used in everything from x-ray machines to radio transmission, computers to power utility and atmospheric science measurement to the Hubble Telescope. Voltmeters can use magnetic fields, electrostatic fields, and plasma phenomena to measure voltage. In this page we talk about PMMC &hellip; <a href=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Voltmeters<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":694,"parent":9,"menu_order":5,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-330","page","type-page","status-publish","has-post-thumbnail","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v19.10 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Voltmeters - Universe of Instrumentation<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Voltmeters - Universe of Instrumentation\" \/>\n<meta property=\"og:description\" content=\"The voltmeter is a key instrument in our world of electrical technology. They are used in everything from x-ray machines to radio transmission, computers to power utility and atmospheric science measurement to the Hubble Telescope. Voltmeters can use magnetic fields, electrostatic fields, and plasma phenomena to measure voltage. In this page we talk about PMMC &hellip; Continue reading Voltmeters\" \/>\n<meta property=\"og:url\" content=\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/\" \/>\n<meta property=\"og:site_name\" content=\"Universe of Instrumentation\" \/>\n<meta property=\"article:modified_time\" content=\"2017-03-09T22:10:53+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/Unit1Banner900-1a.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"800\" \/>\n\t<meta property=\"og:image:height\" content=\"254\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/\",\"url\":\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/\",\"name\":\"Voltmeters - Universe of Instrumentation\",\"isPartOf\":{\"@id\":\"http:\/\/www.edisontc.org\/ui\/#website\"},\"datePublished\":\"2016-02-24T23:53:19+00:00\",\"dateModified\":\"2017-03-09T22:10:53+00:00\",\"breadcrumb\":{\"@id\":\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"http:\/\/www.edisontc.org\/ui\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Home\",\"item\":\"http:\/\/www.edisontc.org\/ui\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Course\",\"item\":\"http:\/\/www.edisontc.org\/ui\/home\/course\/\"},{\"@type\":\"ListItem\",\"position\":4,\"name\":\"Unit I Measuring Electricity\",\"item\":\"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/\"},{\"@type\":\"ListItem\",\"position\":5,\"name\":\"Voltmeters\"}]},{\"@type\":\"WebSite\",\"@id\":\"http:\/\/www.edisontc.org\/ui\/#website\",\"url\":\"http:\/\/www.edisontc.org\/ui\/\",\"name\":\"Universe of Instrumentation\",\"description\":\"Engineering tools and instruments\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"http:\/\/www.edisontc.org\/ui\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-US\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Voltmeters - Universe of Instrumentation","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/","og_locale":"en_US","og_type":"article","og_title":"Voltmeters - Universe of Instrumentation","og_description":"The voltmeter is a key instrument in our world of electrical technology. They are used in everything from x-ray machines to radio transmission, computers to power utility and atmospheric science measurement to the Hubble Telescope. Voltmeters can use magnetic fields, electrostatic fields, and plasma phenomena to measure voltage. In this page we talk about PMMC &hellip; Continue reading Voltmeters","og_url":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/","og_site_name":"Universe of Instrumentation","article_modified_time":"2017-03-09T22:10:53+00:00","og_image":[{"width":800,"height":254,"url":"http:\/\/www.edisontc.org\/ui\/files\/2016\/02\/Unit1Banner900-1a.jpg","type":"image\/jpeg"}],"twitter_card":"summary_large_image","twitter_misc":{"Est. reading time":"3 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/","url":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/","name":"Voltmeters - Universe of Instrumentation","isPartOf":{"@id":"http:\/\/www.edisontc.org\/ui\/#website"},"datePublished":"2016-02-24T23:53:19+00:00","dateModified":"2017-03-09T22:10:53+00:00","breadcrumb":{"@id":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/"]}]},{"@type":"BreadcrumbList","@id":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/voltmeters\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"http:\/\/www.edisontc.org\/ui\/"},{"@type":"ListItem","position":2,"name":"Home","item":"http:\/\/www.edisontc.org\/ui\/"},{"@type":"ListItem","position":3,"name":"Course","item":"http:\/\/www.edisontc.org\/ui\/home\/course\/"},{"@type":"ListItem","position":4,"name":"Unit I Measuring Electricity","item":"http:\/\/www.edisontc.org\/ui\/home\/course\/unit-i\/"},{"@type":"ListItem","position":5,"name":"Voltmeters"}]},{"@type":"WebSite","@id":"http:\/\/www.edisontc.org\/ui\/#website","url":"http:\/\/www.edisontc.org\/ui\/","name":"Universe of Instrumentation","description":"Engineering tools and instruments","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"http:\/\/www.edisontc.org\/ui\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"}]}},"_links":{"self":[{"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/pages\/330","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/comments?post=330"}],"version-history":[{"count":33,"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/pages\/330\/revisions"}],"predecessor-version":[{"id":903,"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/pages\/330\/revisions\/903"}],"up":[{"embeddable":true,"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/pages\/9"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/media\/694"}],"wp:attachment":[{"href":"http:\/\/www.edisontc.org\/ui\/wp-json\/wp\/v2\/media?parent=330"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}