{"id":3974,"date":"2026-05-12T09:46:46","date_gmt":"2026-05-12T09:46:46","guid":{"rendered":"https:\/\/lp.szlogic.cn\/glossary\/open-circuit-inductance-ocl-in-ethernet-transformers\/"},"modified":"2026-05-26T03:30:27","modified_gmt":"2026-05-26T03:30:27","slug":"open-circuit-inductance-ocl-in-ethernet-transformers","status":"publish","type":"post","link":"https:\/\/lp.szlogic.cn\/ru\/glossary\/open-circuit-inductance-ocl-in-ethernet-transformers","title":{"rendered":"What Is Open Circuit Inductance (OCL) in Ethernet Transformers?"},"content":{"rendered":"<figure class=\"wp-block-image aligncenter size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1200\" height=\"712\" src=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/5cc8bdb5ce014bb492c5eca30a57120b.webp\" alt=\"What Is OCL?\" class=\"wp-image-3970\" srcset=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/5cc8bdb5ce014bb492c5eca30a57120b.webp 1200w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/5cc8bdb5ce014bb492c5eca30a57120b-300x178.webp 300w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/5cc8bdb5ce014bb492c5eca30a57120b-1024x608.webp 1024w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/5cc8bdb5ce014bb492c5eca30a57120b-768x456.webp 768w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/5cc8bdb5ce014bb492c5eca30a57120b-18x12.webp 18w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">In Ethernet networking and signal transmission, the electrical performance of a LAN transformer plays a critical role in maintaining stable, interference-free communication. One of the most important parameters in magnetic components\u2014especially <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/store-17548-lan-transformer.htm\">Ethernet Transformers<\/a> \u2014is Open Circuit Inductance (OCL).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In this article, we explain what OCL is, why it matters, how it&#8217;s measured, and how it applies directly to the performance of <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/\">LINK-PP\u2019s<\/a> LAN magnetics solutions.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" >&#x1f50d;What Is OCL?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Open Circuit Inductance<\/strong>, abbreviated as <strong>OCL<\/strong>, refers to the inductance measured on one winding of a transformer <strong>when all other windings are left open<\/strong> (unconnected). This value reflects how much magnetic energy the coil can store under unloaded conditions, which directly impacts signal coupling, noise suppression, and compliance with Ethernet standards such as <strong>IEEE 802.3<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In Ethernet applications, OCL is essential for ensuring:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p>Efficient signal transmission across differential pairs<\/p><\/li><li><p>Common-mode noise rejection<\/p><\/li><li><p>Stable impedance matching<\/p><\/li><li><p>Proper isolation between PHY and magnetics<\/p><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" >&#x1f527;How Is OCL Measured?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">OCL is typically measured using an LCR meter under specific test conditions, most commonly:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p><strong>Test frequency<\/strong>: 100 kHz<\/p><\/li><li><p><strong>Signal level<\/strong>: 100 mVrms<\/p><\/li><li><p><strong>DC bias current<\/strong>: 8 mA (or as specified)<\/p><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">It is essential that all <strong>secondary windings are left open<\/strong> during the test, allowing the meter to read the magnetizing inductance of the primary winding without the influence of mutual coupling.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img decoding=\"async\" width=\"1200\" height=\"712\" src=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/34451f919bc945aa89c55a99bcf516ee.webp\" alt=\"Open Circuit Inductance (OCL)\" class=\"wp-image-3971\" srcset=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/34451f919bc945aa89c55a99bcf516ee.webp 1200w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/34451f919bc945aa89c55a99bcf516ee-300x178.webp 300w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/34451f919bc945aa89c55a99bcf516ee-1024x608.webp 1024w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/34451f919bc945aa89c55a99bcf516ee-768x456.webp 768w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/34451f919bc945aa89c55a99bcf516ee-18x12.webp 18w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" >&#x1f3af;Applications and Performance Impact<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A well-designed <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/store-17548-lan-transformer.htm\">Ethernet transformer<\/a> with appropriate OCL ensures smooth signal transmission in high-speed Ethernet environments such as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p><strong>10\/100\/1000Base-T\/2.5\/5\/10G<\/strong> networks<\/p><\/li><li><p><strong>PoE\/PoE+ Ethernet applications<\/strong><\/p><\/li><li><p><strong>Industrial and automotive Ethernet systems<\/strong><\/p><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">In these systems, OCL is directly tied to:<\/p>\n\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<colgroup><col style=\"width: 271px;\"\/><col style=\"min-width: 25px;\"\/><\/colgroup><tbody><tr><th colspan=\"1\" rowspan=\"1\" colwidth=\"271\"><p>Performance Factor<\/p><\/th><th colspan=\"1\" rowspan=\"1\"><p>Impact of OCL<\/p><\/th><\/tr><tr><td colspan=\"1\" rowspan=\"1\" colwidth=\"271\"><p>Signal Integrity<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>High OCL preserves waveform fidelity<\/p><\/td><\/tr><tr><td colspan=\"1\" rowspan=\"1\" colwidth=\"271\"><p>EMI\/Noise Suppression<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>OCL acts as a low-pass filter for common-mode noise<\/p><\/td><\/tr><tr><td colspan=\"1\" rowspan=\"1\" colwidth=\"271\"><p>Compliance with IEEE Specs<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Meeting OCL thresholds is mandatory<\/p><\/td><\/tr><tr><td colspan=\"1\" rowspan=\"1\" colwidth=\"271\"><p>Magnetizing Current<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Higher OCL leads to lower core excitation current<\/p><\/td><\/tr><\/tbody>\n<\/table>\n<\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" >&#x2696;&#xfe0f;OCL vs. Leakage Inductance<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">While both are inductance parameters, they represent different behaviors in transformers:<\/p>\n\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<colgroup><col style=\"min-width: 25px;\"\/><col style=\"min-width: 25px;\"\/><col style=\"min-width: 25px;\"\/><\/colgroup><tbody><tr><th colspan=\"1\" rowspan=\"1\"><p>Parameter<\/p><\/th><th colspan=\"1\" rowspan=\"1\"><p>Definition<\/p><\/th><th colspan=\"1\" rowspan=\"1\"><p>Test Setup<\/p><\/th><\/tr><tr><td colspan=\"1\" rowspan=\"1\"><p><strong>OCL<\/strong><\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Inductance with other windings open<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Secondary open<\/p><\/td><\/tr><tr><td colspan=\"1\" rowspan=\"1\"><p><strong>Leakage Inductance<\/strong><\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Inductance when other windings are shorted<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Secondary shorted<\/p><\/td><\/tr><\/tbody>\n<\/table>\n<\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>Understanding both values is critical when evaluating transformer performance across frequency ranges.<\/p><\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" >&#x1f3c6; LINK-PP\u2019s OCL-Optimized LAN Magnetics<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">As a trusted manufacturer and long-term OEM supplier to companies like <strong>Texas Instruments<\/strong>, <strong>Intel<\/strong>, and <strong>Cisco<\/strong>, <strong>LINK-PP<\/strong> provides a diverse portfolio of <strong>LAN transformer magnetics<\/strong> engineered with tightly controlled <strong>Open Circuit Inductance (OCL)<\/strong> specifications. These components ensure superior signal integrity, EMI suppression, and compliance with IEEE Ethernet standards.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img decoding=\"async\" width=\"1200\" height=\"712\" src=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/da6f13c8797b47669860c849bf6e1c78.webp\" alt=\"LAN transformer magnetics\" class=\"wp-image-3972\" srcset=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/da6f13c8797b47669860c849bf6e1c78.webp 1200w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/da6f13c8797b47669860c849bf6e1c78-300x178.webp 300w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/da6f13c8797b47669860c849bf6e1c78-1024x608.webp 1024w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/da6f13c8797b47669860c849bf6e1c78-768x456.webp 768w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/da6f13c8797b47669860c849bf6e1c78-18x12.webp 18w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Explore our collection:<br\/>&#x1f517; <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/store-17548-lan-transformer.htm\">LINK-PP LAN Transformer Magnetics<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Some featured Products include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p><a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/products\/452808.htm\"><strong>LP84822ANL<\/strong><\/a> \u2013 48-Pin 1000Base-T PoE+ Magnetics Transformer<br\/><strong>OCL:<\/strong> 350\u03bcH Min @100kHz, 0.1V, 8mA DC Bias<br\/>Ideal for gigabit PoE+ Ethernet applications requiring high isolation and robust performance.<\/p><\/li><li><p><a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/products\/466256.htm\"><strong>LP72423ANL<\/strong><\/a> \u2013 Single-Port 10GBase-T Magnetic Module<br\/><strong>OCL:<\/strong> 200\u03bcH Min @100kHz, 100mA<br\/>Designed for high-speed 10G networks, ensuring signal clarity under high current conditions.<\/p><\/li><li><p><a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/products\/439792.htm\"><strong>LPJG0926HENL<\/strong><\/a> \u2013 RJ45 Connector with Integrated 1000Base-T Magnetics for PoE+<br\/><strong>Inductance OCL:<\/strong><br\/> 350\u03bcH Min @100kHz, 0.1V, 8mA DC Bias<br\/> 120\u03bcH Min @100kHz, 0.1V, 18mA DC Bias<br\/>A compact magnetic RJ45 module combining PoE+ support and optimized inductance for stable Ethernet transmission.<\/p><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">All LINK-PP magnetics are <strong>100% OCL-tested<\/strong> (not batch-tested), ensuring consistent quality and reliable electrical performance across every unit shipped.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" >&#x2705; Conclusion<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Open Circuit Inductance (OCL) is a foundational parameter in evaluating Ethernet transformer performance, directly influencing signal integrity, EMI behavior, and IEEE compliance. For designers and engineers, understanding how OCL is measured and how it affects key transmission metrics is essential when selecting LAN magnetics for high-speed and PoE-enabled networks. LINK-PP\u2019s commitment to precision OCL testing and product consistency positions its LAN transformers as a reliable choice across diverse Ethernet applications\u2014from industrial automation to data center infrastructure.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" >FAQ<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" >What does OCL mean in Ethernet transformers?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">OCL stands for open circuit inductance. You measure it with the secondary winding open. It shows how well your transformer stores energy for Ethernet signals.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" >Why should you care about OCL values?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">You need the right OCL value to keep your Ethernet network stable. Low OCL can cause data loss. LINK-PP transformers list OCL clearly for easy selection.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" >How do you find the OCL value for a transformer?<\/h3>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>Check the <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/message.htm\">datasheet from LINK-PP<\/a> or other trusted brands. Look for OCL at 100 kHz and 25\u00b0C. This helps you match the transformer to your network needs.<\/p><\/blockquote>","protected":false},"excerpt":{"rendered":"<p>Open circuit inductance (OCL) in Ethernet transformers affects signal integrity and EMI suppression; Higher OCL prevents data loss.<\/p>","protected":false},"author":1,"featured_media":3973,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[27],"tags":[23],"class_list":["post-3974","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-glossary","tag-link-pp-lan-transformers"],"blocksy_meta":[],"acf":[],"_links":{"self":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts\/3974","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/comments?post=3974"}],"version-history":[{"count":2,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts\/3974\/revisions"}],"predecessor-version":[{"id":7943,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts\/3974\/revisions\/7943"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/media\/3973"}],"wp:attachment":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/media?parent=3974"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/categories?post=3974"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/tags?post=3974"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}