{"id":2404,"date":"2026-04-09T18:04:13","date_gmt":"2026-04-09T10:04:13","guid":{"rendered":"https:\/\/zmgs-global.com\/?p=2404"},"modified":"2026-04-09T18:04:15","modified_gmt":"2026-04-09T10:04:15","slug":"how-is-a-current-transformer-connected","status":"publish","type":"post","link":"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html","title":{"rendered":"Comment un transformateur de courant est-il connect\u00e9 ?"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"2404\" class=\"elementor elementor-2404\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-dd2b898 e-flex e-con-boxed e-con e-parent\" data-id=\"dd2b898\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-454c041 elementor-widget elementor-widget-text-editor\" data-id=\"454c041\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Someone once wired a current transformer backward. The meters showed negative values. The protection relays stayed quiet when they should have tripped.<\/p><p>This article walks through how to connect a\u00a0<a href=\"https:\/\/zmgs-global.com\/products\/current-transformer\"><strong>Current Transformer<\/strong><\/a>\u00a0in real-world installations. The practical steps, common mistakes, and details that matter.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-98ddba6 elementor-widget elementor-widget-heading\" data-id=\"98ddba6\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#What_a_Current_Transformer_Does_Before_Connection\" >What a Current Transformer Does Before Connection<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#Step-by-Step_Guide_to_Connect_a_Current_Transformer\" >Step-by-Step Guide to Connect a Current Transformer<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#Wiring_Configurations_for_a_Current_Transformer\" >Wiring Configurations for a Current Transformer<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#Common_Mistakes_When_Connecting_a_Current_Transformer\" >Common Mistakes When Connecting a Current Transformer<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#Practical_Examples_of_Connecting_a_Current_Transformer\" >Practical Examples of Connecting a Current Transformer<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#Safety_Practices_When_Working_with_a_Current_Transformer\" >Safety Practices When Working with a Current Transformer<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#Conclusion_on_Connecting_a_Current_Transformer\" >Conclusion on Connecting a Current Transformer<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/zmgs-global.com\/fr\/how-is-a-current-transformer-connected.html\/#FAQ\" >FAQ<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"What_a_Current_Transformer_Does_Before_Connection\"><\/span>What a Current Transformer Does Before Connection<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-29100f4 elementor-widget elementor-widget-text-editor\" data-id=\"29100f4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Before connecting a current transformer, it helps to remember what it actually does.<\/p><p>The device reduces high primary current to a lower, measurable secondary value. Standard secondary currents are 1A and 5A. This allows meters and relays to work safely without handling high current directly.<\/p><p>The primary side is usually a busbar or cable passing through the device&#8217;s opening. No direct electrical connection is needed on the primary for most low voltage versions. For high voltage units, the primary is often a single turn built into the insulation.<\/p><p>Different types are used for different jobs. A\u00a0High Voltage Current Transformer\u00a0sits in substations. A\u00a0Low Voltage Current Transformermounts inside panels. A\u00a0<a href=\"https:\/\/zmgs-global.com\/products\/zero-sequence-current-transformer\"><strong>Zero Sequence Current Transformer<\/strong><\/a>\u00a0surrounds all three phases to detect ground faults. Each connects slightly differently, but the core principles are the same.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-93bf212 elementor-widget elementor-widget-image\" data-id=\"93bf212\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" width=\"800\" height=\"600\" src=\"https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/09\/Zero-Sequence-CurrentTransformer.png\" class=\"attachment-full size-full wp-image-522\" alt=\"Zero Sequence Current Transformer\" srcset=\"https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/09\/Zero-Sequence-CurrentTransformer.png 800w, https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/09\/Zero-Sequence-CurrentTransformer-768x576.png 768w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a4df0c0 elementor-widget elementor-widget-heading\" data-id=\"a4df0c0\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"Step-by-Step_Guide_to_Connect_a_Current_Transformer\"><\/span>Step-by-Step Guide to Connect a Current Transformer<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7405b5f elementor-widget elementor-widget-heading\" data-id=\"7405b5f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Mount the Current Transformer<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-07a99b6 elementor-widget elementor-widget-text-editor\" data-id=\"07a99b6\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>For a\u00a0<a href=\"https:\/\/zmgs-global.com\/products\/low-voltage-current-transformer\"><strong>Low Voltage Current Transformer<\/strong><\/a>, the device is usually clamped around the primary conductor or busbar. The conductor must pass through the center opening. Nothing else should be inside that opening except the intended conductor.<\/p><p>For a high voltage version, the current transformer is often mounted on a steel structure or inside a switchgear compartment. The primary conductor is bolted to its terminals.<\/p><p>Zero sequence current transformer installation is different. All three phase conductors must pass through the same opening. The neutral conductor may also be included depending on the grounding scheme.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8b6f23e elementor-widget elementor-widget-heading\" data-id=\"8b6f23e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Connect the Primary Side of a Current Transformer<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-27251ac elementor-widget elementor-widget-text-editor\" data-id=\"27251ac\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Primary connection depends on the current transformer type.<\/p><p>For a\u00a0<a href=\"https:\/\/zmgs-global.com\/products\/high-voltage-current-voltage-transformer\"><strong>High Voltage Current Transformer<\/strong><\/a>, the primary is connected in series with the line. The device has dedicated primary terminals. The line current flows through the primary winding.<\/p><p>For a low voltage version, the primary conductor is simply passed through the window. No electrical connection is made to the current transformer itself. The number of primary turns affects the ratio. One pass through the opening equals one primary turn. Some devices allow multiple passes to change the ratio.<\/p><p>Safety warning: Never open the secondary circuit of a current transformer under load. An open secondary can induce dangerously high voltage.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7fd1a7b elementor-widget elementor-widget-heading\" data-id=\"7fd1a7b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Wire the Secondary Side of a Current Transformer<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5345100 elementor-widget elementor-widget-text-editor\" data-id=\"5345100\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Secondary wiring is where most mistakes happen.<\/p><p>The secondary terminals of a current transformer are usually marked S1 and S2. These connect to the meter or relay.<\/p><p>One common mistake is swapping S1 and S2. This reverses polarity. The meter reads negative or the relay operates incorrectly. Polarity matters especially for directional protection or differential schemes involving a current transformer.<\/p><p>The secondary wires should be sized appropriately. Long runs need larger wire to keep the burden low. The secondary circuit must be continuous. No open circuits.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9c56db9 elementor-widget elementor-widget-heading\" data-id=\"9c56db9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Ground the Secondary Circuit of a Current Transformer<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f07b8b2 elementor-widget elementor-widget-text-editor\" data-id=\"f07b8b2\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>One secondary terminal of the current transformer should be grounded. The ground connection prevents the secondary voltage from rising to dangerous levels if insulation fails.<\/p><p>The grounding point is typically at the current transformer itself or inside the panel where its secondary terminates. Only one ground per circuit to avoid ground loops.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-34da8a8 elementor-widget elementor-widget-image\" data-id=\"34da8a8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"800\" height=\"600\" src=\"https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/09\/1742794782589822.png\" class=\"attachment-full size-full wp-image-729\" alt=\"High Voltage Current\/Voltage Transformer\" srcset=\"https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/09\/1742794782589822.png 800w, https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/09\/1742794782589822-768x576.png 768w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-c02174d elementor-widget elementor-widget-heading\" data-id=\"c02174d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Verify Polarity and Ratio of a Current Transformer<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a455e95 elementor-widget elementor-widget-text-editor\" data-id=\"a455e95\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>After physical connection comes verification.<\/p><p>Polarity can be verified by applying a small Direct Current voltage to the primary and observing the secondary reading. If the reading is positive when expected, polarity is correct. Primary injection testing using a test set is another reliable method.<\/p><p>The ratio test confirms that the turns ratio matches the nameplate rating. This step catches wiring errors before the system goes live.<\/p><p>For a zero sequence current transformer, the verification is slightly different. With all three phases balanced, the secondary output should be near zero. Any significant output indicates a wiring problem or a ground fault.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-c65505a elementor-widget elementor-widget-heading\" data-id=\"c65505a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"Wiring_Configurations_for_a_Current_Transformer\"><\/span>Wiring Configurations for a Current Transformer<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-01f0942 elementor-widget elementor-widget-text-editor\" data-id=\"01f0942\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>The table below shows common connection schemes for different applications.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2edb482 elementor-widget elementor-widget-tablepress-table\" data-id=\"2edb482\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"tablepress-table.default\">\n\t\t\t\t\t\n<table id=\"tablepress-47\" class=\"tablepress tablepress-id-47\">\n<thead>\n<tr class=\"row-1\">\n\t<th class=\"column-1\">Application<\/th><th class=\"column-2\">Connection Method<\/th><th class=\"column-3\">Polarity Requirement<\/th>\n<\/tr>\n<\/thead>\n<tbody class=\"row-striping row-hover\">\n<tr class=\"row-2\">\n\t<td class=\"column-1\">Single-phase metering<\/td><td class=\"column-2\">Secondary to meter<\/td><td class=\"column-3\">S1 to meter line, S2 to meter load<\/td>\n<\/tr>\n<tr class=\"row-3\">\n\t<td class=\"column-1\">Three-phase metering<\/td><td class=\"column-2\">Three units, one per phase<\/td><td class=\"column-3\">Consistent orientation<\/td>\n<\/tr>\n<tr class=\"row-4\">\n\t<td class=\"column-1\">Overcurrent protection<\/td><td class=\"column-2\">Secondary to relay<\/td><td class=\"column-3\">S1 to relay input<\/td>\n<\/tr>\n<tr class=\"row-5\">\n\t<td class=\"column-1\">Directional protection<\/td><td class=\"column-2\">Secondary to relay<\/td><td class=\"column-3\">Must match reference voltage<\/td>\n<\/tr>\n<tr class=\"row-6\">\n\t<td class=\"column-1\">Ground fault detection<\/td><td class=\"column-2\">Zero sequence type<\/td><td class=\"column-3\">All phases through one unit<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<!-- #tablepress-47 from cache -->\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ca290cf elementor-widget elementor-widget-heading\" data-id=\"ca290cf\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"Common_Mistakes_When_Connecting_a_Current_Transformer\"><\/span> Common Mistakes When Connecting a Current Transformer<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-c32bd32 elementor-widget elementor-widget-heading\" data-id=\"c32bd32\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Open Circuit on Secondary Side<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-06c282e elementor-widget elementor-widget-text-editor\" data-id=\"06c282e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>The most dangerous mistake. A current transformer with an open secondary can generate dangerously high voltage. Always short the secondary before disconnecting any wiring.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e49c44b elementor-widget elementor-widget-heading\" data-id=\"e49c44b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Wrong Polarity<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3eb037c elementor-widget elementor-widget-text-editor\" data-id=\"3eb037c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Swapping S1 and S2 on a current transformer causes reversed polarity. The meter reads backward. Protection relays may operate when they should not.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0aeaa99 elementor-widget elementor-widget-heading\" data-id=\"0aeaa99\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Multiple Grounds<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a6e0889 elementor-widget elementor-widget-text-editor\" data-id=\"a6e0889\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Grounding both secondary terminals of a current transformer creates a ground loop. This can cause circulating currents and measurement errors. Only one ground per circuit.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-05455e7 elementor-widget elementor-widget-image\" data-id=\"05455e7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"800\" height=\"800\" src=\"https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/07\/Low-Voltage-Current-Transformer-LMZJ1-0.5.jpg\" class=\"attachment-full size-full wp-image-287\" alt=\"Low Voltage Current Transformer-LMZ(J)1-0.5\" srcset=\"https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/07\/Low-Voltage-Current-Transformer-LMZJ1-0.5.jpg 800w, https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/07\/Low-Voltage-Current-Transformer-LMZJ1-0.5-150x150.jpg 150w, https:\/\/zmgs-global.com\/wp-content\/uploads\/2025\/07\/Low-Voltage-Current-Transformer-LMZJ1-0.5-768x768.jpg 768w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a957126 elementor-widget elementor-widget-heading\" data-id=\"a957126\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Wrong Ratio<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5a3da7f elementor-widget elementor-widget-text-editor\" data-id=\"5a3da7f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Using a current transformer with the wrong ratio produces inaccurate readings. Always match the ratio to the primary current.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d663ba3 elementor-widget elementor-widget-heading\" data-id=\"d663ba3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Incorrect Primary Turns<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5698d79 elementor-widget elementor-widget-text-editor\" data-id=\"5698d79\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Some current transformers allow multiple primary passes. One pass through the window equals one turn. Two passes equal two turns. This changes the effective ratio.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-56d7e3a elementor-widget elementor-widget-heading\" data-id=\"56d7e3a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"Practical_Examples_of_Connecting_a_Current_Transformer\"><\/span>Practical Examples of Connecting a Current Transformer<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-57726ac elementor-widget elementor-widget-heading\" data-id=\"57726ac\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\"> Low Voltage Current Transformer for Metering<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5e0ffee elementor-widget elementor-widget-text-editor\" data-id=\"5e0ffee\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>A facility needs to measure current on a low voltage feeder. The electrician selects a low voltage current transformer. The primary conductor passes through the window once. The secondary wires run to a power meter, S1 to S1, S2 to S2.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9e83455 elementor-widget elementor-widget-heading\" data-id=\"9e83455\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">High Voltage Current Transformer for Protection<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2f7beca elementor-widget elementor-widget-text-editor\" data-id=\"2f7beca\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>A substation feeder uses a high voltage current transformer for overcurrent protection. The primary is connected in series with the line. The secondary connects to a protection relay.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-731084b elementor-widget elementor-widget-heading\" data-id=\"731084b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Zero Sequence Current Transformer for Ground Fault Detection<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7b3c208 elementor-widget elementor-widget-text-editor\" data-id=\"7b3c208\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>A commercial building uses a\u00a0Zero Sequence Current Transformer\u00a0for ground fault protection. All three phase conductors pass through the device&#8217;s opening. Under normal conditions, the secondary current is near zero.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-13be381 elementor-widget elementor-widget-heading\" data-id=\"13be381\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"Safety_Practices_When_Working_with_a_Current_Transformer\"><\/span>Safety Practices When Working with a Current Transformer<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9b4530d elementor-widget elementor-widget-text-editor\" data-id=\"9b4530d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<ul><li>De-energize the primary circuit before working on a current transformer if possible<\/li><li>Apply appropriate Personal Protective Equipment (PPE)<\/li><li>Never open secondary terminals of a current transformer<\/li><li>Always short the secondary terminals before removing the device<\/li><li>Ground the secondary circuit of the current transformer<\/li><li>Replace all covers before turning on power<\/li><\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5d19803 elementor-widget elementor-widget-heading\" data-id=\"5d19803\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"Conclusion_on_Connecting_a_Current_Transformer\"><\/span>Conclusion on Connecting a Current Transformer<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-908a2dc elementor-widget elementor-widget-text-editor\" data-id=\"908a2dc\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Connecting a current transformer requires attention to detail. Mount it correctly. Wire the secondary with correct polarity. Ground one point. Verify before energizing.<\/p><p>If you want to know more about Current Transformer, please read <a href=\"https:\/\/zmgs-global.com\/how-to-check-if-current-transformer-is-working-or-not.html\"><strong>How to check if current transformer is working or not<\/strong><\/a>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-168edf8a e-con-full e-flex e-con e-parent\" data-id=\"168edf8a\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-45934a90 elementor-widget__width-inherit elementor-widget elementor-widget-heading\" data-id=\"45934a90\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><span class=\"ez-toc-section\" id=\"FAQ\"><\/span>FAQ<span class=\"ez-toc-section-end\"><\/span><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4c8deb5d elementor-widget elementor-widget-n-accordion\" data-id=\"4c8deb5d\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;default_state&quot;:&quot;expanded&quot;,&quot;max_items_expended&quot;:&quot;one&quot;,&quot;n_accordion_animation_duration&quot;:{&quot;unit&quot;:&quot;ms&quot;,&quot;size&quot;:400,&quot;sizes&quot;:[]}}\" data-widget_type=\"nested-accordion.default\">\n\t\t\t\t\t\t\t<div class=\"e-n-accordion\" aria-label=\"Accordion. Open links with Enter or Space, close with Escape, and navigate with Arrow Keys\">\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1280\" class=\"e-n-accordion-item\" open>\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"1\" tabindex=\"0\" aria-expanded=\"true\" aria-controls=\"e-n-accordion-item-1280\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> What happens if the secondary terminals of a current transformer are left open while the primary is energized? <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1280\" class=\"elementor-element elementor-element-74fa3f02 e-con-full e-flex e-con e-child\" data-id=\"74fa3f02\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-75a9340 elementor-widget elementor-widget-text-editor\" data-id=\"75a9340\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>The secondary voltage can rise to dangerously high levels. This applies to all types of current transformers. Always short the secondary before disconnecting any wiring.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1281\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"2\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1281\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> How can you tell if a current transformer is wired with the correct polarity after installation? <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1281\" class=\"elementor-element elementor-element-2b8183ec e-con-full e-flex e-con e-child\" data-id=\"2b8183ec\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-cd47568 elementor-widget elementor-widget-text-editor\" data-id=\"cd47568\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Apply a small Direct Current voltage to the primary and observe the secondary reading. If positive when expected, polarity is correct. If negative, the wires are swapped.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1282\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"3\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1282\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Why is grounding required on the secondary circuit of a current transformer? <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1282\" class=\"elementor-element elementor-element-4124ac98 e-con-full e-flex e-con e-child\" data-id=\"4124ac98\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-abd202e elementor-widget elementor-widget-text-editor\" data-id=\"abd202e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Grounding one secondary terminal prevents dangerous voltage rise if insulation fails. Only one ground per circuit. This is a standard safety requirement for all current transformer installations.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<script type=\"application\/ld+json\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"What happens if the secondary terminals of a current transformer are left open while the primary is energized?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The secondary voltage can rise to dangerously high levels. This applies to all types of current transformers. Always short the secondary before disconnecting any wiring.\"}},{\"@type\":\"Question\",\"name\":\"How can you tell if a current transformer is wired with the correct polarity after installation?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Apply a small Direct Current voltage to the primary and observe the secondary reading. If positive when expected, polarity is correct. If negative, the wires are swapped.\"}},{\"@type\":\"Question\",\"name\":\"Why is grounding required on the secondary circuit of a current transformer?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Grounding one secondary terminal prevents dangerous voltage rise if insulation fails. Only one ground per circuit. This is a standard safety requirement for all current transformer installations.\"}}]}<\/script>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"Someone once wired a current transformer backward. The meters showed negative values. The protection relays stayed quiet when they should have tripped. This article walks through how to connect a\u00a0Current Transformer\u00a0in real-world installations. The practical steps, common mistakes, and details that matter. What a Current Transformer Does Before Connection Before connecting a current transformer, it [&hellip;]","protected":false},"author":6,"featured_media":598,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[46],"tags":[],"class_list":["post-2404","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-guide"],"acf":[],"_links":{"self":[{"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/posts\/2404","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/comments?post=2404"}],"version-history":[{"count":0,"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/posts\/2404\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/media\/598"}],"wp:attachment":[{"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/media?parent=2404"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/categories?post=2404"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zmgs-global.com\/fr\/wp-json\/wp\/v2\/tags?post=2404"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}