{"id":100047,"date":"2026-02-15T20:09:13","date_gmt":"2026-02-15T20:09:13","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100047"},"modified":"2026-02-15T20:09:13","modified_gmt":"2026-02-15T20:09:13","slug":"braking-resistor-calculator","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/bs\/calculators\/braking-resistor-calculator\/","title":{"rendered":"Braking Resistor Calculator | VFD Dynamic Braking | Free Online Tool"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Braking Resistor Calculator\",\"alternateName\":[\"VFD Brake Resistor Calculator\",\"Dynamic Braking Calculator\"],\"description\":\"Calculate braking resistor resistance, power, and energy for VFD dynamic braking applications.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/braking-resistor-calculator\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any (Web Browser)\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2024-01-01\",\"dateModified\":\"2025-06-01\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true,\"featureList\":[\"Resistance calculation\",\"Power rating\",\"Energy per cycle\",\"Duty cycle check\",\"Auto-calculation\"],\"keywords\":\"braking resistor, VFD, dynamic braking, brake chopper, DC bus\"}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What is a braking resistor in a VFD system?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"A braking resistor dissipates regenerative energy as heat when a motor decelerates faster than it would coast to stop. The VFD's brake chopper switches the DC bus to the resistor when voltage exceeds a threshold (typically 115-130% of nominal DC bus voltage).\"}},\n{\"@type\":\"Question\",\"name\":\"How do I calculate the braking resistor value?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"R_min = V\u00b2dc \/ P_brake, where Vdc is the DC bus voltage (typically \u221a2 \u00d7 V_line) and P_brake is the maximum braking power. The resistor must handle peak braking power without exceeding the brake chopper's current limit.\"}},\n{\"@type\":\"Question\",\"name\":\"What is the DC bus voltage for common supply voltages?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"DC bus \u2248 \u221a2 \u00d7 V_line. For 400V supply: Vdc \u2248 565V (brake threshold ~750V). For 480V: Vdc \u2248 680V (threshold ~800V). For 230V: Vdc \u2248 325V (threshold ~400V).\"}},\n{\"@type\":\"Question\",\"name\":\"How do I determine braking power?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"P_brake = J \u00d7 \u03c9\u00b2 \/ (2 \u00d7 t_decel), where J is total inertia (kg\u00b7m\u00b2), \u03c9 is angular velocity (rad\/s), and t_decel is deceleration time. For quick estimation: P_brake \u2248 P_motor \u00d7 (rated_speed\/decel_time) for full-speed stops.\"}},\n{\"@type\":\"Question\",\"name\":\"What duty cycle should I use?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Duty cycle = braking_time \/ cycle_time \u00d7 100%. Typical: 5-10% for occasional stops, 20-40% for frequent cycling. The continuous power rating of the resistor = peak power \u00d7 duty cycle. Check the VFD manual for maximum allowed duty cycle.\"}}\n]}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[\n{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},\n{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},\n{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Braking Resistor\",\"item\":\"https:\/\/vibromera.eu\/calculators\/braking-resistor-calculator\/\"}\n]}\n<\/script>\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n\n<link 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16px;font-size:13px;color:var(--vc-ink-muted)}.vc-footer a{color:var(--vc-accent);text-decoration:none}.vc-footer a:hover{text-decoration:underline}.vc-footer-links{margin-top:8px;font-size:12px}.vc-footer-links a{margin:0 8px}\n@media print{.vc-section-body{max-height:none!important}.vc-faq-a{max-height:none!important}.vc-results{max-height:none!important;padding:24px!important}.vc-copy-btn,.vc-section-chevron,.vc-faq-chevron,.vc-presets,.vc-promo{display:none!important}}\n<\/style>\n\n<div class=\"vc-calculator\" id=\"vc-braking-resistor-calculator\">\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool<\/p>\n    <h1 class=\"vc-header-title\">Braking Resistor Calculator<\/h1>\n    <p class=\"vc-header-subtitle\">Size a dynamic braking resistor for VFD applications. R = V\u00b2<sub>dc<\/sub> \/ P<sub>brake<\/sub>. Calculate resistance, power rating, and energy per braking cycle.<\/p>\n    <div class=\"vc-badges\"><span class=\"vc-badge\">VFD Braking<\/span><span class=\"vc-badge\">R = V\u00b2\/P<\/span><span class=\"vc-badge\">Energy \/ Cycle<\/span><\/div>\n<\/header>\n\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-pmotor\">Motor Power <span class=\"vc-label-hint\">(kW)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-pmotor\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 15\" value=\"15\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-vac\">Supply Voltage <span class=\"vc-label-hint\">(V AC line)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-vac\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 400\" value=\"400\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-speed\">Motor Speed <span class=\"vc-label-hint\">(RPM)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-speed\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 1500\" value=\"1500\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-tdecel\">Deceleration Time <span class=\"vc-label-hint\">(s)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-tdecel\" inputmode=\"decimal\" step=\"any\" min=\"0.1\" placeholder=\"e.g. 5\" value=\"5\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-inertia\">Total Inertia J <span class=\"vc-label-hint\">(kg\u00b7m\u00b2)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-inertia\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 0.5\" value=\"0.5\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-duty\">Duty Cycle <span class=\"vc-label-hint\">(% \u2014 braking\/cycle)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-duty\" inputmode=\"decimal\" step=\"1\" min=\"1\" max=\"100\" placeholder=\"e.g. 10\" value=\"10\">\n            <\/div>\n        <\/div>\n        <div class=\"vc-presets\">\n            <div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-pm=\"7.5\" data-v=\"400\" data-n=\"1500\" data-t=\"3\" data-j=\"0.2\" data-d=\"10\">7.5 kW Conveyor<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-pm=\"15\" data-v=\"400\" data-n=\"1500\" data-t=\"5\" data-j=\"0.5\" data-d=\"10\">15 kW Hoist<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-pm=\"37\" data-v=\"400\" data-n=\"1500\" data-t=\"8\" data-j=\"2\" data-d=\"20\">37 kW Centrifuge<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-pm=\"75\" data-v=\"400\" data-n=\"1000\" data-t=\"10\" data-j=\"5\" data-d=\"5\">75 kW Flywheel<\/button>\n        <\/div>\n    <\/form>\n\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\">\n            <h2 class=\"vc-results-title\">Results<\/h2>\n            <button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\"><svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy<\/button>\n        <\/div>\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\">\n                <div class=\"vc-rcard-label\">Min Braking Resistance<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-rmin\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Peak Braking Power<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-ppeak\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Energy per Cycle<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-energy\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Continuous Power Rating<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-pcont\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">DC Bus Voltage<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-vdc\">\u2014<\/div>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udcd8<\/span><span class=\"vc-section-title\">Theory &amp; Formulas<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner vc-theory\">\n        <h3>Braking Resistance<\/h3>\n        <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n        <h3>Kinetic Energy &amp; Braking Power<\/h3>\n        <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\n        <div class=\"vc-formula-box\" id=\"vc-katex-3\"><\/div>\n        <div class=\"vc-warning-box\"><p style=\"margin:0;font-size:14px;color:var(--vc-ink-secondary)\"><strong>\u26a0\ufe0f<\/strong> Always verify with VFD manufacturer datasheet. Minimum resistance must not exceed brake chopper current limit.<\/p><\/div>\n    <\/div><\/div>\n<\/div>\n\n<div class=\"vc-section\" id=\"vc-sec-related\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udd17<\/span><span class=\"vc-section-title\">Related Calculators<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-related\">\n        <a class=\"vc-related-link\" href=\"\/calculators\/vfd-selection-calculator\/\">VFD Selection<\/a>\n        <a class=\"vc-related-link\" href=\"\/calculators\/motor-starting-current\/\">Motor Starting Current<\/a>\n        <a class=\"vc-related-link\" href=\"\/calculators\/three-phase-motor-power\/\">Three-Phase Motor Power<\/a>\n        <a class=\"vc-related-link\" href=\"\/calculators\/motor-torque-from-current\/\">Motor Torque<\/a>\n    <\/div><\/div><\/div>\n<\/div>\n\n<div class=\"vc-section\" id=\"vc-sec-faq\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\u2753<\/span><span class=\"vc-section-title\">Frequently Asked Questions<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div><\/div><\/div>\n<\/div>\n\n<div class=\"vc-promo\"><div class=\"vc-promo-text\"><strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>Professional instruments. 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Power: '+$('vc-r-pcont').textContent+'\\nVdc: '+$('vc-r-vdc').textContent+'\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nvibromera.eu';\n        if(navigator.clipboard){navigator.clipboard.writeText(text).then(function(){var b=$('vc-copy-btn');b.classList.add('vc-copied');b.innerHTML='<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><polyline points=\"20 6 9 17 4 12\"\/><\/svg> Copied!';setTimeout(function(){b.classList.remove('vc-copied');b.innerHTML='<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy'},2000)})}\n    });\n\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn){btn.addEventListener('click',function(){var s=this.closest('.vc-section');s.classList.toggle('vc-open');this.setAttribute('aria-expanded',s.classList.contains('vc-open'))})});\n\n    var faqData=[\n        {q:'What is a braking resistor in a VFD system?',a:'<p>A braking resistor dissipates regenerative energy as heat when a motor decelerates. The VFD brake chopper switches the DC bus to the resistor when voltage exceeds the threshold.<\/p>'},\n        {q:'How do I calculate the braking resistor value?',a:'<p>R_min = V\u00b2dc \/ P_brake. Vdc \u2248 \u221a2 \u00d7 V_line. P_brake = kinetic energy \/ decel time. The resistor must handle peak power without exceeding chopper current limits.<\/p>'},\n        {q:'What is the DC bus voltage?',a:'<p>Vdc \u2248 \u221a2 \u00d7 V_line. For 400V: ~565V. For 480V: ~680V. For 230V: ~325V. Brake threshold is typically 115\u2013130% of nominal Vdc.<\/p>'},\n        {q:'How do I determine braking power?',a:'<p>P_brake = \u00bd \u00d7 J \u00d7 \u03c9\u00b2 \/ t_decel. J is total inertia (motor + load), \u03c9 = 2\u03c0\u00d7n\/60, t_decel is desired stop time.<\/p>'},\n        {q:'What duty cycle should I use?',a:'<p>Duty = braking_time \/ cycle_time. 5\u201310% for occasional stops, 20\u201340% for frequent cycling. Resistor continuous rating = peak \u00d7 duty.<\/p>'}\n    ];\n    var fl=$('vc-faq-list');faqData.forEach(function(f){fl.innerHTML+='<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>'+f.q+'<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">'+f.a+'<\/div><\/div><\/div>'});\n    fl.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(b)b.closest('.vc-faq-item').classList.toggle('vc-open')});\n\n    function saveHistory(e){var k='vc_history_'+SLUG;var a=[];try{a=JSON.parse(localStorage.getItem(k))||[]}catch(x){}e._ts=new Date().toISOString();a.unshift(e);if(a.length>10)a=a.slice(0,10);try{localStorage.setItem(k,JSON.stringify(a))}catch(x){}}\n    function loadParams(){var p=new URLSearchParams(window.location.search);p.forEach(function(v,k){var el=$(k)||$('vc-'+k);if(el)el.value=v})}\n    function renderFormulas(){try{\n        katex.render('R_{min} = \\\\frac{V_{dc}^2}{P_{brake}} \\\\quad [\\\\Omega]',$('vc-katex-1'),{displayMode:true,throwOnError:false});\n        katex.render('E_k = \\\\frac{1}{2} J \\\\omega^2 \\\\quad [\\\\text{J}]',$('vc-katex-2'),{displayMode:true,throwOnError:false});\n        katex.render('P_{brake} = \\\\frac{E_k}{t_{decel}} \\\\quad [\\\\text{W}]',$('vc-katex-3'),{displayMode:true,throwOnError:false});\n    }catch(e){}}\n    function init(){loadParams();renderFormulas();calculate()}\n    if(document.readyState==='loading'){document.addEventListener('DOMContentLoaded',init)}else{init()}\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Free online braking resistor calculator for VFD applications. Calculate resistance R=V\u00b2dc\/P_brake, power rating, and energy per cycle for dynamic braking.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100047","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/calculator\/100047","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":1,"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/calculator\/100047\/revisions"}],"predecessor-version":[{"id":100358,"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/calculator\/100047\/revisions\/100358"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/media?parent=100047"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/categories?post=100047"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/bs\/wp-json\/wp\/v2\/tags?post=100047"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}