{"id":2381,"date":"2026-04-21T08:29:40","date_gmt":"2026-04-21T08:29:40","guid":{"rendered":"https:\/\/electrical.lazyhungryminds.com\/?p=2381"},"modified":"2026-04-21T08:29:45","modified_gmt":"2026-04-21T08:29:45","slug":"induction-motor-problems-crawling-and-cogging-simple-explanation","status":"publish","type":"post","link":"https:\/\/electrical.lazyhungryminds.com\/index.php\/2026\/04\/21\/induction-motor-problems-crawling-and-cogging-simple-explanation\/","title":{"rendered":"Induction Motor Problems: Crawling and Cogging (Simple Explanation)"},"content":{"rendered":"\n<p>Induction motors are widely used in industries because they are simple, strong, and require very little maintenance. However, during operation\u2014especially at startup\u2014they can face two common problems: <strong>crawling<\/strong> and <strong>cogging<\/strong>. These issues mainly occur in <strong>squirrel-cage induction motors<\/strong> and affect smooth performance.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">What is Crawling in an Induction Motor?<\/h1>\n\n\n\n<p>Crawling is a condition where the motor runs at a <strong>very low speed (about 1\/7th of its normal speed)<\/strong> instead of reaching full speed.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Why Does Crawling Happen?<\/h2>\n\n\n\n<p>Crawling occurs due to disturbances in the motor\u2019s magnetic field, known as <strong>harmonics<\/strong>.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The main magnetic field tries to rotate the motor at full speed.<\/li>\n\n\n\n<li>A specific harmonic (called the <strong>7th harmonic<\/strong>) creates a backward force.<\/li>\n\n\n\n<li>This backward force can slow the motor down and make it run at low speed.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Key Points About Crawling<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Caused by unwanted magnetic effects (harmonics).<\/li>\n\n\n\n<li>More common when the motor is running with a <strong>light load<\/strong>.<\/li>\n\n\n\n<li>Reduces motor efficiency and causes unstable operation.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How to Prevent Crawling<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use <strong>proper winding design<\/strong> to reduce harmonics.<\/li>\n\n\n\n<li>Design stator slots carefully.<\/li>\n\n\n\n<li>Ensure the motor operates under proper load conditions.<\/li>\n<\/ul>\n\n\n\n<h1 class=\"wp-block-heading\">What is Cogging in an Induction Motor?<\/h1>\n\n\n\n<p>Cogging, also known as <strong>magnetic locking<\/strong>, is a condition where the motor <strong>fails to start<\/strong> even when power is supplied.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Why Does Cogging Happen?<\/h2>\n\n\n\n<p>Cogging occurs when the <strong>stator and rotor teeth align perfectly<\/strong>, creating a strong magnetic attraction.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>This alignment locks the rotor in place.<\/li>\n\n\n\n<li>It is more likely when the number of stator slots matches or is a multiple of rotor slots.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Key Points About Cogging<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The motor does not start at all.<\/li>\n\n\n\n<li>Caused by strong magnetic locking between stator and rotor.<\/li>\n\n\n\n<li>Usually happens due to poor motor design.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How to Prevent Cogging<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use <strong>skewed rotor slots<\/strong> (slightly twisted design).<\/li>\n\n\n\n<li>Avoid matching stator and rotor slot numbers.<\/li>\n\n\n\n<li>Improve design accuracy during manufacturing.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Difference Between Crawling and Cogging<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Feature<\/th><th>Crawling<\/th><th>Cogging<\/th><\/tr><\/thead><tbody><tr><td>Motor behavior<\/td><td>Runs at very low speed (~1\/7 speed)<\/td><td>Does not start<\/td><\/tr><tr><td>Main cause<\/td><td>Harmonics (7th harmonic)<\/td><td>Magnetic locking of teeth<\/td><\/tr><tr><td>Operation<\/td><td>Motor runs abnormally<\/td><td>Motor stays still<\/td><\/tr><tr><td>Solution<\/td><td>Reduce harmonics<\/td><td>Avoid slot alignment<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Induction motors are widely used in industries because they are simple, strong, and require very little maintenance. However, during operation\u2014especially at startup\u2014they can face two common problems: crawling and cogging. These issues mainly occur in squirrel-cage induction motors and affect&#8230; <a class=\"more-link\" href=\"https:\/\/electrical.lazyhungryminds.com\/index.php\/2026\/04\/21\/induction-motor-problems-crawling-and-cogging-simple-explanation\/\">Continue Reading &rarr;<\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"rank_math_lock_modified_date":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1,6,30,31],"tags":[],"class_list":["post-2381","post","type-post","status-publish","format-standard","hentry","category-uncategorized","category-electrical","category-electrical-basics","category-electrical-machines"],"jetpack_featured_media_url":"","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/posts\/2381","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/comments?post=2381"}],"version-history":[{"count":1,"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/posts\/2381\/revisions"}],"predecessor-version":[{"id":2382,"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/posts\/2381\/revisions\/2382"}],"wp:attachment":[{"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/media?parent=2381"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/categories?post=2381"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/electrical.lazyhungryminds.com\/index.php\/wp-json\/wp\/v2\/tags?post=2381"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}