{"id":31,"date":"2020-01-18T16:19:04","date_gmt":"2020-01-18T21:19:04","guid":{"rendered":"https:\/\/opentextbc.ca\/basicmotorcontrol\/chapter\/single-phase-systems-vs-three-phase-systems\/"},"modified":"2023-03-02T11:51:54","modified_gmt":"2023-03-02T16:51:54","slug":"single-phase-systems-vs-three-phase-systems","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/basicmotorcontrol\/chapter\/single-phase-systems-vs-three-phase-systems\/","title":{"raw":"Single-Phase Systems vs. Three-Phase Systems","rendered":"Single-Phase Systems vs. Three-Phase Systems"},"content":{"raw":"Click play on the following audio player to listen along as you read this section.\r\n\r\nhttps:\/\/media.bccampus.ca\/id\/0_tlm8abg6?width=608&amp;height=80&amp;playerId=23449753\r\n\r\nIn electrical systems, we use the terms \"single-phase\" and \"three-phase\" fairly often, so a brief description of them will help us moving forward.\r\n\r\n[pb_glossary id=\"206\"]Single-phase systems[\/pb_glossary] are the simplest electrical circuits. They require only two lines: one for power to go in and the other is a return path for current. These are often called Line 1 and Line 2, or Line 1 and Neutral. Current only has one path to travel in a single-phase circuit, and all of the [pb_glossary id=\"242\"]control circuits[\/pb_glossary] that we will be looking at are single-phase.\r\n\r\n[caption id=\"attachment_30\" align=\"aligncenter\" width=\"1024\"]<img class=\"wp-image-29 size-large\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-1024x466.png\" alt=\"\" width=\"1024\" height=\"466\" \/> AC single phase circuit[\/caption]\r\n\r\n[pb_glossary id=\"205\"]Three-phase systems[\/pb_glossary] are bit more complex. They use three current carrying conductors, called Line 1, Line 2, and Line 3, which have a 120\u00b0 phase shift in the [pb_glossary id=\"219\"]voltage[\/pb_glossary] and current waveforms between them. Each of these conductors are connected to a three-phase load, like a three-phase motor.\r\n\r\nWhen in operation, a balanced three-phase load (such as a motor) has each of its three line's current values cancel each other out, and so it does not require a return conductor. These loads can be connected in Wye or Delta configuration, which will be covered later in this text.\r\n\r\n[caption id=\"attachment_30\" align=\"aligncenter\" width=\"1024\"]<img class=\"size-large wp-image-30\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-1024x389.png\" alt=\"\" width=\"1024\" height=\"389\" \/> 3-phase circuit[\/caption]\r\n\r\nUnbalanced three-phase loads are mainly connected in the Wye configuration where the central point is used as a neutral to carry any stray return currents. In practice a motor is always a balanced three-phase load.\r\n\r\nAll of the [pb_glossary id=\"243\"]power circuits[\/pb_glossary] that we will be looking at will be three-phase.\r\n\r\nAll of the control circuits that we will be looking at will be single-phase.","rendered":"<p>Click play on the following audio player to listen along as you read this section.<\/p>\n<p><iframe loading=\"lazy\" id=\"kaltura_player\" title=\"Single-phase systems vs three-phase systems\" src=\"https:\/\/api.ca.kaltura.com\/p\/148\/sp\/14800\/embedIframeJs\/uiconf_id\/23449753\/partner_id\/148?iframeembed=true&#38;playerId=kaltura_player&#38;entry_id=0_tlm8abg6&#38;flashvars[leadWithHTML5]=true&#38;flashvars[streamerType]=auto&#38;flashvars[localizationCode]=en&#38;flashvars[sideBarContainer.plugin]=true&#38;flashvars[sideBarContainer.position]=left&#38;flashvars[sideBarContainer.clickToClose]=true&#38;flashvars[chapters.plugin]=true&#38;flashvars[chapters.layout]=vertical&#38;flashvars[chapters.thumbnailRotator]=false&#38;flashvars[streamSelector.plugin]=true&#38;flashvars[EmbedPlayer.SpinnerTarget]=videoHolder&#38;flashvars[dualScreen.plugin]=true&#38;flashvars[Kaltura.addCrossoriginToIframe]=true&#38;wid=0_y93tz7u0\" width=\"608\" height=\"80\" allowfullscreen=\"allowfullscreen\" sandbox=\"allow-downloads allow-forms allow-same-origin allow-scripts allow-top-navigation allow-pointer-lock allow-popups allow-modals allow-orientation-lock allow-popups-to-escape-sandbox allow-presentation allow-top-navigation-by-user-activation\" frameborder=\"0\"><\/iframe><\/p>\n<p>In electrical systems, we use the terms &#8220;single-phase&#8221; and &#8220;three-phase&#8221; fairly often, so a brief description of them will help us moving forward.<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_31_206\">Single-phase systems<\/a> are the simplest electrical circuits. They require only two lines: one for power to go in and the other is a return path for current. These are often called Line 1 and Line 2, or Line 1 and Neutral. Current only has one path to travel in a single-phase circuit, and all of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_31_242\">control circuits<\/a> that we will be looking at are single-phase.<\/p>\n<figure id=\"attachment_30\" aria-describedby=\"caption-attachment-30\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-29 size-large\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-1024x466.png\" alt=\"\" width=\"1024\" height=\"466\" srcset=\"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-1024x466.png 1024w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-300x136.png 300w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-768x349.png 768w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-1536x699.png 1536w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-2048x931.png 2048w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-65x30.png 65w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-225x102.png 225w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/01\/AC-Single-Phase-e1580151582184-350x159.png 350w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption id=\"caption-attachment-30\" class=\"wp-caption-text\">AC single phase circuit<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_31_205\">Three-phase systems<\/a> are bit more complex. They use three current carrying conductors, called Line 1, Line 2, and Line 3, which have a 120\u00b0 phase shift in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_31_219\">voltage<\/a> and current waveforms between them. Each of these conductors are connected to a three-phase load, like a three-phase motor.<\/p>\n<p>When in operation, a balanced three-phase load (such as a motor) has each of its three line&#8217;s current values cancel each other out, and so it does not require a return conductor. These loads can be connected in Wye or Delta configuration, which will be covered later in this text.<\/p>\n<figure id=\"attachment_30\" aria-describedby=\"caption-attachment-30\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-30\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-1024x389.png\" alt=\"\" width=\"1024\" height=\"389\" srcset=\"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-1024x389.png 1024w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-300x114.png 300w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-768x292.png 768w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-1536x583.png 1536w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-2048x778.png 2048w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-65x25.png 65w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-225x85.png 225w, https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-content\/uploads\/sites\/314\/2020\/08\/Wye-Line-2-e1580151890722-350x133.png 350w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption id=\"caption-attachment-30\" class=\"wp-caption-text\">3-phase circuit<\/figcaption><\/figure>\n<p>Unbalanced three-phase loads are mainly connected in the Wye configuration where the central point is used as a neutral to carry any stray return currents. In practice a motor is always a balanced three-phase load.<\/p>\n<p>All of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_31_243\">power circuits<\/a> that we will be looking at will be three-phase.<\/p>\n<p>All of the control circuits that we will be looking at will be single-phase.<\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_31_206\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_31_206\"><div tabindex=\"-1\"><p>The simplest electrical circuit. It requires only two lines: one for power to go in and the other is a return path for current. These are often called Line 1 and Line 2, or Line 1 and Neutral. Current only has one path to travel in a single-phase circuit, such as a control circuit.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_31_242\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_31_242\"><div tabindex=\"-1\"><p>In contrast to the Power Circuit, the Control Circuit consists of inputs, in the form of switches, pushbuttons or pilot devices, which when activated, can either directly, or through a magnetic motor starter, energize a load. The Control Circuit often operates at a lower voltage than the Power Circuit for safety and ease of installation.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_31_205\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_31_205\"><div tabindex=\"-1\"><p>An electrical circuit that uses three current carrying conductors, called Line 1, Line 2, and Line 3, which have a 120\u00b0 phase shift in the voltage and current waveforms between them. The Power Circuit of three-phase motors is an example of a three-phase circuit.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_31_219\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_31_219\"><div tabindex=\"-1\"><p>The difference in electric potential between two points, which is defined as the work needed per unit of charge to move a test charge between the two points. It is measured in volts (V).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_31_243\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_31_243\"><div tabindex=\"-1\"><p>In contrast to the control circuit, the power circuit provides the large values of voltage and current used by the motor itself. Must be equipped with overcurrent and overload protection, and horsepower-rated contacts in the control gear equal to the voltage and current ratings of the motor.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":90,"menu_order":4,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-31","chapter","type-chapter","status-publish","hentry"],"part":21,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/pressbooks\/v2\/chapters\/31","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/wp\/v2\/users\/90"}],"version-history":[{"count":4,"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/pressbooks\/v2\/chapters\/31\/revisions"}],"predecessor-version":[{"id":434,"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/pressbooks\/v2\/chapters\/31\/revisions\/434"}],"part":[{"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/pressbooks\/v2\/parts\/21"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/pressbooks\/v2\/chapters\/31\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/wp\/v2\/media?parent=31"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/pressbooks\/v2\/chapter-type?post=31"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/wp\/v2\/contributor?post=31"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/basicmotorcontrol\/wp-json\/wp\/v2\/license?post=31"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}