{"id":95480,"date":"2026-05-26T10:00:00","date_gmt":"2026-05-26T08:00:00","guid":{"rendered":"https:\/\/www.lecosinus.fr\/?p=95480"},"modified":"2026-09-15T09:10:29","modified_gmt":"2026-09-15T07:10:29","slug":"transformer-dimmer-harmonics-precautions","status":"publish","type":"post","link":"https:\/\/www.lecosinus.fr\/en\/transformateur-gradateur-harmoniques-precautions\/","title":{"rendered":"Precautions to take when using a transformer with a dimmer"},"content":{"rendered":"<h2 class=\"wp-block-heading\">The Impact of Phase-Angle and Burst-Firing Power Controllers on Transformer Sizing <\/h2>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">In many industrial applications, power regulation has become essential for accurately controlling thermal processes, heating elements, and various types of production equipment. \n\nAmong the most widely used solutions are thyristor power controllers, which provide precise and efficient power regulation.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, one important aspect is often overlooked: <strong>the chosen control method has a direct impact on the behaviour and sizing of the transformer installed downstream.<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">At Le Cosinus, we regularly assist our customers in addressing these challenges. An <a href=\"https:\/\/www.lecosinus.fr\/en\/transformers\/\" data-type=\"link\" data-id=\"https:\/\/www.lecosinus.fr\/transformateurs\/\" target=\"_self\">electrical transformer<\/a> that is not properly matched to its electrical environment can quickly become a source of overheating, excessive vibration, increased energy losses, or even premature failure.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Understanding the effects of different power control technologies makes it possible to design transformers that are more reliable, more durable, and better suited to real operating conditions.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"1024\" src=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors.png\" alt=\"Comparaison entre un gradateur \u00e0 angle de phase et un gradateur \u00e0 train d&#039;ondes et leurs effets sur un transformateur.\" class=\"wp-image-95502\" srcset=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors.png 1200w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors-300x300.png 300w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors-1024x1024.png 1024w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors-150x150.png 150w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors-768x768.png 768w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors-12x12.png 12w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors-600x600.png 600w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Transformer-dimmer-Beware-of-errors-100x100.png 100w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Phase-Angle Power Control: The Challenge of Harmonics<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Operating Principle and Applications<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Le gradateur \u00e0 angle de phase fonctionne en \u00ab\u00a0d\u00e9coupant\u00a0\u00bb la sinuso\u00efde \u00e0 chaque demi-p\u00e9riode. Cette technologie permet une r\u00e9gulation tr\u00e8s pr\u00e9cise de la puissance, mais elle g\u00e9n\u00e8re \u00e9galement une <a href=\"https:\/\/www.lecosinus.fr\/en\/how-harmonics-affect-electrical-transformers\/\" data-type=\"link\" data-id=\"https:\/\/www.lecosinus.fr\/quel-est-limpact-des-harmoniques-sur-le-transformateur-electrique\/\">forte distorsion harmonique<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This control method remains essential for applications requiring continuous power delivery or very low thermal inertia, including:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>Industrial lighting and infrared lamps: <\/strong>It provides a stable light output while preventing flickering and stroboscopic effects.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Inductive loads and transformers: <\/strong>When combined with a soft-start function, it limits the high inrush currents associated with transformer magnetisation.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"406\" src=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle.png\" alt=\"gradateur et transformateur\u200b,gradateur,transformateur\" class=\"wp-image-95484\" srcset=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle.png 2004w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle-300x118.png 300w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle-1024x401.png 1024w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle-768x301.png 768w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle-1536x602.png 1536w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle-18x7.png 18w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Phase-Angle-600x235.png 600w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Effects on the Transformer<\/h2>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">The rapid switching of the thyristor generates very high voltage rise rates (dV\/dt). For the transformer, this results in several important consequences:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>Increased core losses:<\/strong> Rapid variations in magnetic flux generate higher eddy current losses within the transformer core.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Higher copper (I\u00b2R) losses:<\/strong> High-order harmonics increase the skin effect in the conductors, raising their effective AC resistance and, consequently, the associated copper losses.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Mechanical vibration and acoustic noise:<\/strong> Flux discontinuities place greater mechanical stress on the laminated magnetic core, resulting in increased vibration and audible noise.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Greater insulation stress:<\/strong> The transformer windings are subjected to higher electrical stress between adjacent turns, which can accelerate insulation ageing.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/48243687.hs-sites.com\/transformateur-industriel-expertise-et-applications\"><img loading=\"lazy\" decoding=\"async\" width=\"770\" height=\"587\" src=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/05\/Transformateurs-industriels-expertises-et-applications.jpeg\" alt=\"gradateur et transformateur\u200b,gradateur,transformateur\" class=\"wp-image-95878\" srcset=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/05\/Transformateurs-industriels-expertises-et-applications.jpeg 770w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/05\/Transformateurs-industriels-expertises-et-applications-300x229.jpeg 300w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/05\/Transformateurs-industriels-expertises-et-applications-768x585.jpeg 768w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/05\/Transformateurs-industriels-expertises-et-applications-16x12.jpeg 16w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/05\/Transformateurs-industriels-expertises-et-applications-600x457.jpeg 600w\" sizes=\"auto, (max-width: 770px) 100vw, 770px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Our Approach at Le Cosinus<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">To minimise these effects, we adapt the transformer's design from the very beginning of the project by:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Optimising the magnetic flux density to prevent core saturation. <\/li>\n\n\n\n<li>Using high-performance grain-oriented electrical steel laminations whenever required.<\/li>\n\n\n\n<li>Taking the <strong>K-factor<\/strong> into account to correctly size the transformer's apparent power based on harmonic distortion and the increased conductor losses caused by the skin effect.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Burst-Firing Power Control: Thermal and Mechanical Challenges <\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Operating Principle and Applications<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">A <strong>burst-firing power controller<\/strong> operates differently. It allows complete AC cycles to pass before temporarily interrupting the supply. \n\nUnlike high-frequency switching systems, it operates solely at the mains frequency <strong>(50 Hz in most European countries).<strong \/><\/p>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">Because switching occurs at the <strong>zero-crossing point<\/strong> of the AC waveform, this technology offers excellent <strong>electromagnetic compatibility (EMC)<\/strong>, generating very little electromagnetic interference (EMI).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This control method is particularly well suited to loads with <strong>high thermal inertia<\/strong>, such as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>Industrial furnaces and electric heating elements:<\/strong> Their thermal inertia naturally smooths the on\/off power cycles, resulting in minimal temperature fluctuations.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">However, burst-firing control is not recommended\u2014and may even be unsuitable\u2014for certain applications, including: <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>Electric motors: <\/strong>Repeated start\/stop cycles generate mechanical shocks, vibration, and increased mechanical stress.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Lighting systems:<\/strong> The intermittent power supply can produce noticeable and uncomfortable stroboscopic effects.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"515\" src=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train.png\" alt=\"gradateur et transformateur\u200b,gradateur,transformateur\" class=\"wp-image-95485\" srcset=\"https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train.png 1860w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train-300x136.png 300w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train-1024x466.png 1024w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train-768x349.png 768w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train-1536x699.png 1536w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train-18x8.png 18w, https:\/\/www.lecosinus.fr\/wp-content\/uploads\/2026\/09\/Wave-Train-600x273.png 600w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Effects on the Transformer<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The use of <strong>burst firing control<\/strong> on the primary side of a transformer requires specific precautions.<\/p>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">If the power controller does not properly manage switching synchronisation or residual magnetic flux, a significant <strong>inrush current<\/strong> can occur each time a new burst starts, potentially causing saturation of the magnetic core.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The transformer is also subjected to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>Repeated thermal cycles:<\/strong> Alternating between full load operation and idle periods places mechanical stress on the windings and accelerates insulation ageing.<\/li>\n\n\n\n<li class=\"translation-block\"><strong>Significant mechanical forces:<\/strong> Current peaks generate repeated electrodynamic forces within the internal transformer structure.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Our Design Approach at Le Cosinus<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">For this type of application, we focus on a robust design, both from a magnetic and mechanical perspective:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Reinforced winding support and improved tightening of the magnetic core assembly.<\/li>\n\n\n\n<li>Larger core cross-sections to ensure operation well away from the saturation zone and limit overcurrents during cycle restarts.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Comparative Summary for Your Applications<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Feature<\/strong><\/td><td class=\"has-text-align-left\" data-align=\"left\"><strong>Phase Angle<\/strong><\/td><td class=\"has-text-align-left\" data-align=\"left\"><strong>Wave Train<\/strong><\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Applications types<\/td><td class=\"has-text-align-left\" data-align=\"left\">Lighting, IR Lamps, Inductive Loads<\/td><td class=\"has-text-align-left\" data-align=\"left\">Industrial Ovens, Pure Heating Elements<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Major constraint<\/td><td class=\"has-text-align-left\" data-align=\"left\">High Harmonics &amp; Iron Losses <\/td><td class=\"has-text-align-left\" data-align=\"left\">Mechanical Shocks &amp; Risk of Saturation<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Signal frequency<\/td><td class=\"has-text-align-left\" data-align=\"left\">Chopped (harmonic generator)<\/td><td class=\"has-text-align-left\" data-align=\"left\">Pure 50 Hz (time-sequenced)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">THD Current<\/td><td class=\"has-text-align-left\" data-align=\"left\">Very high<\/td><td class=\"has-text-align-left\" data-align=\"left\">Low (Excellent EMC)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Adaptation:  Le Cosinus<\/td><td class=\"has-text-align-left\" data-align=\"left\">Reduced Induction &amp; Application of the K-Factor<\/td><td class=\"has-text-align-left\" data-align=\"left\">Reinforced Steel Section &amp; Mechanical Locking<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Le Cosinus expertise <\/h2>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">For nearly 80 years, <a href=\"https:\/\/www.lecosinus.fr\/en\/\" data-type=\"link\" data-id=\"https:\/\/www.lecosinus.fr\/\" target=\"_self\">Le Cosinus<\/a>  has been designing transformers for demanding industrial environments.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When a transformer is used in combination with a power controller, simply \"adding extra margin\" is not enough. Proper sizing must take into account: <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The actual current waveform; <\/li>\n\n\n\n<li>Thermal constraints; <\/li>\n\n\n\n<li>Mechanical stresses;<\/li>\n\n\n\n<li>Harmonic phenomena generated by the control system.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Our engineering department supports each project to precisely adapt:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Transformer geometry;<\/li>\n\n\n\n<li>Magnetic materials;<\/li>\n\n\n\n<li>Insulation systems;<\/li>\n\n\n\n<li>Cooling solutions.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph translation-block\">Do you have a project involving a <strong>thyristor power controller? <\/strong>\n\nFeel free to provide us with your installation's technical specifications so that we can deliver a transformer design truly tailored to your application.<\/p>\n\n\n\n<div class=\"hs-cta-embed hs-cta-simple-placeholder hs-cta-embed-185420320831\" style=\"max-width:100%;max-height:100%;width:700px;height:239.53125px\" data-hubspot-wrapper-cta-id=\"185420320831\">\r\n  <a href=\"https:\/\/cta-service-cms2.hubspot.com\/web-interactives\/public\/v1\/track\/redirect?encryptedPayload=AVxigLJ%2B8uzXIlYd5F1Cg72GDEo4S1p9zzkqyLAlT3McWV%2BDNRWsrtcQFwhBihGlWDL3nSWdQscvugwJIEM%2Blo0sWyqvQjAIafWdESsEYmcGkml4PxESyXNVWWZLqCNHgrHd%2BIsg8qUJHAayrn2LojP7LZPyflwCywOPcg8taJdeZJCXxpOTHuE%3D&amp;webInteractiveContentId=185420320831&amp;portalId=48243687\" target=\"_blank\" rel=\"noopener\">\r\n    <img decoding=\"async\" alt=\"Demande de devis Saisissez votre r&eacute;f&eacute;rence produit ou indiquer les caract&eacute;ristiques du produit recherch&eacute; &nbsp;\" loading=\"lazy\" src=\"https:\/\/no-cache.hubspot.com\/cta\/default\/48243687\/interactive-185420320831.png\" style=\"height: 100%;width: 100%;object-fit: fill\" \/>\r\n  <\/a>\r\n<\/div>","protected":false},"excerpt":{"rendered":"<p>L&rsquo;impact des gradateurs de puissance \u00e0 Angle de Phase et Train d&rsquo;Ondes sur le dimensionnement des transformateurs Dans de nombreuses applications industrielles, la r\u00e9gulation de puissance est devenue indispensable pour piloter avec pr\u00e9cision des proc\u00e9d\u00e9s thermiques, des r\u00e9sistances chauffantes ou encore certaines machines de production. Parmi les solutions les plus utilis\u00e9es, les gradateurs de puissance [&hellip;]<\/p>\n","protected":false},"author":4387,"featured_media":95502,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_seopress_titles_title":"Transformateur et gradateur : les pr\u00e9cautions \u00e0 prendre. | Le Cosinus","_seopress_titles_desc":"Transformateur et gradateur \u00e0 thyristors : pr\u00e9cautions sur les harmoniques, la saturation magn\u00e9tique et l\u2019\u00e9chauffement.","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"none","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"both","_seopress_redirections_param":"","_seopress_redirections_type":301,"_seopress_analysis_target_kw":"gradateur et transformateur\u200b,gradateur,transformateur","_seopress_news_disabled":"","_seopress_video_disabled":"","_seopress_video":[],"_seopress_pro_schemas_manual":[],"_seopress_pro_rich_snippets_disable_all":"","_seopress_pro_rich_snippets_disable":[],"_seopress_pro_schemas":[],"content-type":"","footnotes":""},"categories":[20],"tags":[],"class_list":["post-95480","post","type-post","status-publish","format-standard","has-post-thumbnail","category-guides-conseils"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/posts\/95480","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/users\/4387"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/comments?post=95480"}],"version-history":[{"count":12,"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/posts\/95480\/revisions"}],"predecessor-version":[{"id":96312,"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/posts\/95480\/revisions\/96312"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/media\/95502"}],"wp:attachment":[{"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/media?parent=95480"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/categories?post=95480"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lecosinus.fr\/en\/wp-json\/wp\/v2\/tags?post=95480"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}