{"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":"2026-07-11T22:18:25","modified_gmt":"2026-07-11T22:18:25","slug":"braking-resistor-calculator","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/cs\/calculators\/braking-resistor-calculator\/","title":{"rendered":"VFD Braking Resistor Candidate Check | Drive-Specific Inputs"},"content":{"rendered":"\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"VFD Braking Resistor Candidate Check\",\"description\":\"Check electrical on-state and event-demand arithmetic for a candidate VFD braking resistor using drive-specific chopper voltage and minimum resistance plus user-supplied resistor energy per event.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/braking-resistor-calculator\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"dateModified\":\"2026-07-11\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true}<\/script>\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Can minimum braking resistance be calculated from motor power?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. The drive or brake-chopper manufacturer specifies the minimum allowed resistance. Never use a lower value.\"}},{\"@type\":\"Question\",\"name\":\"Can nominal AC line voltage be used as braking-chopper voltage?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. Use the applicable chopper switch-on or specified braking voltage from the exact drive documentation.\"}},{\"@type\":\"Question\",\"name\":\"Does cycle-average power select the resistor?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. The resistor and chopper must also satisfy manufacturer peak power, pulse energy, time-window, temperature, duty and protection limits.\"}}]}<\/script>\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Braking Resistor Candidate Check\",\"item\":\"https:\/\/vibromera.eu\/calculators\/braking-resistor-calculator\/\"}]}<\/script>\r\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\r\n<style>\r\n:root{--vc-bg:#f4f1ec;--vc-surface:#fff;--vc-surface-alt:#f8f6f2;--vc-ink:#1a1a1a;--vc-ink-secondary:#5a5650;--vc-ink-muted:#8a857e;--vc-accent:#c85a2a;--vc-accent-hover:#b04d22;--vc-accent-light:#fdf0ea;--vc-blue:#2a5c8c;--vc-blue-light:#eaf1f8;--vc-green:#2a7a4b;--vc-green-light:#eaf8ef;--vc-yellow:#a67c00;--vc-yellow-light:#fef9e8;--vc-red:#b91c1c;--vc-red-light:#fef2f2;--vc-border:#d9d4cc;--vc-border-light:#e8e4dd;--vc-shadow:0 1px 3px rgba(26,26,26,.06),0 4px 12px rgba(26,26,26,.04);--vc-radius:8px;--vc-radius-lg:12px;--vc-font:'DM Sans',-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;--vc-mono:'JetBrains 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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}\r\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}}\r\n<\/style>\r\n<div class=\"vc-calculator\" id=\"vc-resistor-check\"><header class=\"vc-header\"><p class=\"vc-header-eyebrow\">Drive-specific candidate arithmetic<\/p><h1 class=\"vc-header-title\">VFD Braking Resistor Candidate Check<\/h1><p class=\"vc-header-subtitle\">Check a candidate resistance against the drive maker\u2019s minimum and calculate idealized chopper on-state\/event demands from qualified input data. No resistor is selected automatically.<\/p><div class=\"vc-badges\"><span class=\"vc-badge\">Use drive Uon<\/span><span class=\"vc-badge\">Use manufacturer Rmin<\/span><span class=\"vc-badge\">No AC-line estimate<\/span><\/div><\/header>\r\n<div class=\"vc-card\"><form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\"><div class=\"vc-form-grid\"><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-u\">Specified chopper on voltage Uon <span class=\"vc-label-hint\">(V DC)<\/span><\/label><input class=\"vc-input\" type=\"text\" id=\"vc-u\" inputmode=\"decimal\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-r\">Candidate resistor R <span class=\"vc-label-hint\">(\u03a9)<\/span><\/label><input class=\"vc-input\" type=\"text\" id=\"vc-r\" inputmode=\"decimal\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-rmin\">Drive\/chopper minimum allowed Rmin <span class=\"vc-label-hint\">(\u03a9)<\/span><\/label><input class=\"vc-input\" type=\"text\" id=\"vc-rmin\" inputmode=\"decimal\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-energy\">Energy delivered to resistor per event E <span class=\"vc-label-hint\">(kJ)<\/span><\/label><input class=\"vc-input\" type=\"text\" id=\"vc-energy\" inputmode=\"decimal\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-time\">Braking-event duration t <span class=\"vc-label-hint\">(s)<\/span><\/label><input class=\"vc-input\" type=\"text\" id=\"vc-time\" inputmode=\"decimal\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-events\">Events per hour z<\/label><input class=\"vc-input\" type=\"text\" id=\"vc-events\" inputmode=\"decimal\"><\/div><\/div><div class=\"vc-warning-box\"><p style=\"margin:0\"><strong>Input responsibility:<\/strong> obtain Uon, Rmin and drive\/chopper limits from the exact manual. E must be energy actually delivered to the resistor after accounting for the complete mechanical load, motor\/drive behavior, losses and energy sharing\u2014not motor nameplate power or rotational energy alone.<\/p><\/div><\/form>\r\n<div class=\"vc-results\" id=\"vc-results\"><div class=\"vc-results-head\"><h2 class=\"vc-results-title\">Candidate arithmetic<\/h2><button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">Copy<\/button><\/div><div class=\"vc-result-grid\"><div class=\"vc-rcard vc-rcard-primary\"><div class=\"vc-rcard-label\">Resistance check<\/div><div class=\"vc-rcard-value\" id=\"vc-r-check\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Full-on current Uon\/R<\/div><div class=\"vc-rcard-value\" id=\"vc-r-current\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Full-on electrical power Uon\u00b2\/R<\/div><div class=\"vc-rcard-value\" id=\"vc-r-onpower\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Required event-average power E\/t<\/div><div class=\"vc-rcard-value\" id=\"vc-r-eventpower\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Ideal average on-fraction during event<\/div><div class=\"vc-rcard-value\" id=\"vc-r-fraction\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Energy at full-on for entered t<\/div><div class=\"vc-rcard-value\" id=\"vc-r-fullenergy\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Cycle-average energy rate E\u00b7z\/3600<\/div><div class=\"vc-rcard-value\" id=\"vc-r-cyclepower\">\u2014<\/div><\/div><\/div><p id=\"vc-r-note\" style=\"margin:0;color:var(--vc-ink-secondary)\"><\/p><\/div><\/div>\r\n<div class=\"vc-section vc-open\"><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\">Equations and manufacturer limits<\/span><\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner vc-theory\"><h3>Electrical on-state arithmetic<\/h3><div class=\"vc-formula-box\">Ion = Uon\/R; &nbsp; Pon = Uon\u00b2\/R<\/div><p>Uon is the documented chopper switch-on or braking voltage, not nominal AC line voltage and not a generic Vac\u221a2 estimate. Pon is the ideal electrical power while the chopper is fully on at that voltage; the real chopper is pulsed and voltage varies.<\/p><h3>Event and repetition demand<\/h3><div class=\"vc-formula-box\">Pevent,avg = E\/t; &nbsp; don,ideal = E\/(Pon\u00b7t); &nbsp; Pcycle,avg = E\u00b7z\/3600<\/div><p>The on-fraction is an ideal energy-balance check. A value above 100% means the entered R and Uon cannot dissipate E within t even at continuous on-state. A value at or below 100% does not prove acceptability because chopper ratings, voltage thresholds, resistor pulse-energy curves, temperature and duty limits still govern.<\/p>\r\n<h3>Primary manufacturer boundaries<\/h3><p>The <a href=\"https:\/\/library.e.abb.com\/public\/e97f22d2083e49ebb60fca736494c511\/3AUA0000106244_en_1_C_ACS880-604%201-phase%20brake%20chopper%20units%20as%20modules%20hardware%20manual.pdf\" target=\"_blank\" rel=\"noopener\">ABB ACS880-604 brake-unit manual<\/a> warns never to use a resistance below the minimum for the drive\/chopper and requires both maximum-power and time-window energy checks. The <a href=\"https:\/\/cache.industry.siemens.com\/dl\/files\/385\/109987385\/att_1323395\/v1\/F-TM_ServoDrive_ST_equip_man_1124_en-US.pdf?download=true\" target=\"_blank\" rel=\"noopener\">Siemens F-TM ServoDrive manual<\/a> uses configured Uon for peak Uon\u00b2\/R and separately requires peak and continuous capability checks.<\/p><div class=\"vc-warning-box\"><p style=\"margin:0\"><strong>No selection verdict:<\/strong> also verify drive\/chopper maximum current and power, resistor minimum\/maximum resistance range, pulse energy versus duration, ten-minute or other accumulation windows, continuous rating at ambient temperature, enclosure\/protection, insulation voltage, wiring, fusing, thermal switch and safe mounting clearances exactly as specified by the manufacturers.<\/p><\/div><\/div><\/div><\/div>\r\n<div class=\"vc-section\"><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><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div><\/div><\/div><\/div><footer class=\"vc-footer\"><p>\u00a9 2024\u20132026 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a><\/p><p>Candidate arithmetic only; not a resistor or VFD selection. Scientific review: July 2026.<\/p><\/footer><\/div>\r\n<script>(function(){'use strict';function $(i){return document.getElementById(i)}function p(raw){var s=String(raw).trim().replace(\/\\s+\/g,'');if(!\/^[+]?(?:\\d+(?:[.,]\\d*)?|[.,]\\d+)$\/.test(s))return NaN;var n=Number(s.replace(',','.'));return Number.isFinite(n)&&n>0?n:NaN}function f(n){return n.toFixed(6).replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,'')}function unit(n,u,ku){return n>=1000?f(n\/1000)+' '+ku:f(n)+' '+u}function calc(){var U=p($('vc-u').value),R=p($('vc-r').value),Rmin=p($('vc-rmin').value),E=p($('vc-energy').value)*1000,t=p($('vc-time').value),z=p($('vc-events').value);if(![U,R,Rmin,E,t,z].every(Number.isFinite)){$('vc-results').classList.remove('vc-visible');return}var I=U\/R,Pon=U*U\/R,Pevent=E\/t,frac=E\/(Pon*t),Efull=Pon*t,Pcycle=E*z\/3600,rok=R>=Rmin,feasible=frac<=1;$('vc-r-check').innerHTML='<span style=\"color:var(--vc-'+(rok?'green':'red')+')\">'+(rok?'R \u2265 entered Rmin':'R < entered Rmin')+'<\/span>';$('vc-r-current').innerHTML=f(I)+' <span class=\"vc-rcard-unit\">A<\/span>';$('vc-r-onpower').textContent=unit(Pon,'W','kW');$('vc-r-eventpower').textContent=unit(Pevent,'W','kW');$('vc-r-fraction').innerHTML='<span style=\"color:var(--vc-'+(feasible?'green':'red')+')\">'+f(frac*100)+'%<\/span>';$('vc-r-fullenergy').innerHTML=f(Efull\/1000)+' <span class=\"vc-rcard-unit\">kJ<\/span>';$('vc-r-cyclepower').textContent=unit(Pcycle,'W','kW');$('vc-r-note').textContent=(rok?'Candidate is not below the entered drive Rmin. 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