{"id":1810,"date":"2026-07-27T10:32:42","date_gmt":"2026-07-27T02:32:42","guid":{"rendered":"https:\/\/jutrion.com\/?page_id=1810"},"modified":"2026-07-27T10:36:54","modified_gmt":"2026-07-27T02:36:54","slug":"kalkulator-doboru-generatora","status":"publish","type":"page","link":"https:\/\/jutrion.com\/pl\/tools\/generator-sizing-calculator\/","title":{"rendered":"kalkulator doboru generatora"},"content":{"rendered":"\n<!-- ===== JUTRION Generator Capacity for ATS \u2014 paste into a WordPress \"Custom HTML\" block ===== -->\n<div class=\"jt-calc\">\n  <p class=\"eyebrow\">Motor &amp; switching<\/p>\n  <h1>Generator Sizing Calculator for ATS Backup<\/h1>\n  <p class=\"tool-lede\">Estimate the standby generator kW and kVA from the diversified running load, the largest motor-starting step, a reserve margin, and site derating \u2014 then read the ATS rating that connects it. A planning starting point; confirm the transient voltage dip and step response with the generator manufacturer.<\/p>\n\n  <div class=\"jt-card\"><div class=\"jt-grid\">\n    <div class=\"jt-inputs\">\n      <div class=\"jt-two\">\n        <div class=\"jt-field\"><label for=\"jt-run\">Running load (kW)<\/label><input type=\"number\" id=\"jt-run\" value=\"150\" min=\"0\" step=\"1\" inputmode=\"numeric\"><\/div>\n        <div class=\"jt-field\"><label for=\"jt-pf\">Load power factor<\/label><input type=\"number\" id=\"jt-pf\" value=\"0.8\" min=\"0.5\" max=\"1\" step=\"0.01\" inputmode=\"decimal\"><\/div>\n      <\/div>\n      <div class=\"jt-two\">\n        <div class=\"jt-field\"><label for=\"jt-motor\">Largest motor (kW)<\/label><input type=\"number\" id=\"jt-motor\" value=\"30\" min=\"0\" step=\"1\" inputmode=\"numeric\"><\/div>\n        <div class=\"jt-field\"><label for=\"jt-start\">Start method<\/label>\n          <select id=\"jt-start\"><option value=\"6\">DOL \u2014 direct on line<\/option><option value=\"3\" selected>Star-delta \/ soft start<\/option><option value=\"1.5\">VFD \/ soft (low)<\/option><\/select>\n        <\/div>\n      <\/div>\n      <div class=\"jt-two\">\n        <div class=\"jt-field\"><label for=\"jt-res\">Reserve \/ spare (%)<\/label><input type=\"number\" id=\"jt-res\" value=\"15\" min=\"0\" step=\"1\" inputmode=\"numeric\"><\/div>\n        <div class=\"jt-field\"><label for=\"jt-der\">Site derating (%)<\/label><input type=\"number\" id=\"jt-der\" value=\"0\" min=\"0\" max=\"40\" step=\"1\" inputmode=\"numeric\"><\/div>\n      <\/div>\n      <div class=\"jt-note\"><span>\u24d8<\/span><span>Derating covers altitude above ~1000 m and high ambient temperature. Enter the combined loss as a percentage; the generator maker&#8217;s charts give the exact figure.<\/span><\/div>\n    <\/div>\n    <div class=\"jt-readout\">\n      <div><div class=\"jt-rl\">Generator prime rating<\/div><div class=\"jt-big\"><span id=\"jt-gkva\">\u2014<\/span> <span>kVA<\/span><\/div><\/div>\n      <div class=\"jt-rec row\"><div class=\"k\">Generator kW (0.8 PF)<\/div><div class=\"v\" id=\"jt-gkw\">\u2014<\/div><\/div>\n      <div class=\"jt-rec row\"><div class=\"k\">Governing case<\/div><div class=\"v\" id=\"jt-gov\" style=\"font-size:13px\">\u2014<\/div><\/div>\n      <div class=\"jt-rec row\"><div class=\"k\">ATS rating @ 400 V<\/div><div class=\"v\" id=\"jt-ats\">\u2014<\/div><\/div>\n      <button type=\"button\" class=\"jt-copy\" id=\"jt-copy\">Copy result<\/button>\n    <\/div>\n  <\/div><\/div>\n\n  <div class=\"jt-content\">\n    <h2>Two cases decide the size<\/h2>\n    <p>A generator has to satisfy the larger of two demands, then keep a margin:<\/p>\n    <ul>\n      <li><b>Steady running:<\/b> the whole diversified load in kVA, plus a reserve for future growth, corrected for site derating.<\/li>\n      <li><b>Transient step:<\/b> the moment the largest motor starts while the rest of the load already runs. Motor starting kVA is several times its running kVA and causes a voltage and frequency dip the set must ride through.<\/li>\n    <\/ul>\n    <div class=\"jt-eq\">Running kVA   = kW \/ PF\nStart step kVA = (running kVA \u2212 motor running kVA) + motor kVA \u00d7 start multiple\nGenerator kVA  = max( running \u00d7 (1+reserve) , start step ) \/ (1 \u2212 derating)<\/div>\n    <p>Starting multiples used here (as a multiple of the motor&#8217;s own running kVA): DOL \u2248 6, star-delta\/soft \u2248 3, VFD \u2248 1.5. A VFD or soft starter dramatically lowers the step and can shrink the generator.<\/p>\n\n    <h2>Why the ATS rating follows the generator<\/h2>\n    <p>The transfer switch carries the full standby current, so it is rated from the generator&#8217;s full-load current, not just the average load:<\/p>\n    <div class=\"jt-eq\">I = kVA \u00d7 1000 \/ (\u221a3 \u00d7 V)<\/div>\n    <p>The tool rounds up to the next standard ATS frame. Confirm the AC-31\/AC-33 utilization category, pole count, and whether the neutral is switched against the earthing arrangement.<\/p>\n\n    <div class=\"jt-note\"><span>\u26a0<\/span><span><b>Transient performance is the maker&#8217;s call.<\/b> The allowable voltage dip on motor start, the alternator&#8217;s ability to hold it, and block-load acceptance depend on the specific generator and AVR. Size on this estimate, then verify the step response with the supplier.<\/span><\/div>\n\n    <h2>Frequently asked questions<\/h2>\n    <div class=\"jt-faq\">\n      <details><summary>Why is the generator bigger than my total kW?<\/summary><p>Generators are rated in kVA at 0.8 power factor and must also swallow the motor-starting step. Both push the rating above the simple running kW, which is why kVA and the largest start dominate the sizing.<\/p><\/details>\n      <details><summary>How much does a soft starter or VFD save?<\/summary><p>By cutting the starting multiple from about 6 to 1.5\u20133, the transient step shrinks, so a set sized by the start case can often drop a frame. Where the running load governs instead, the saving is smaller.<\/p><\/details>\n      <details><summary>Prime, standby or continuous rating?<\/summary><p>This tool targets a prime\/standby duty for backup. A continuous base-load duty derates further. Match the rating class to the run hours and load profile with the manufacturer.<\/p><\/details>\n    <\/div>\n\n    <div class=\"jt-cta\">\n      <h2>Connect it with an ATS<\/h2>\n      <p>With the generator kVA and current set, match the transfer switch rating, category, and poles for the changeover.<\/p>\n      <div class=\"jt-cta-btns\">\n        <a class=\"jt-btn\" href=\"https:\/\/jutrion.com\/ats\/\">Explore JUTRION ATS<\/a>\n        <a class=\"jt-btn ghost\" href=\"https:\/\/jutrion.com\/contact\/\">Get a free quote<\/a>\n      <\/div>\n      <p class=\"jt-related\">Related products: <a href=\"https:\/\/jutrion.com\/ats\/\">ATS<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/acb\/\">ACB<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/mccb\/\">MCCB<\/a><\/p>\n    <\/div>\n\n    <div class=\"jt-std\"><strong>Standards referenced<\/strong>ISO 8528 (generating sets \u2014 ratings &amp; performance) \u00b7 IEC 60947-6-1 (transfer switching equipment) \u00b7 IEC 60038 (voltages).<\/div>\n    <p class=\"jt-fine\">Planning estimate for guidance only. Final generator rating, transient performance, and ATS selection must be confirmed by a qualified person and the generator manufacturer against the actual load profile and site conditions.<\/p>\n  <\/div>\n<\/div>\n\n<script>\n(function(){\n  var $=function(id){return document.getElementById(id);};\n  var run=$('jt-run'),pf=$('jt-pf'),motor=$('jt-motor'),start=$('jt-start'),res=$('jt-res'),der=$('jt-der'),\n      gkvaEl=$('jt-gkva'),gkwEl=$('jt-gkw'),govEl=$('jt-gov'),atsEl=$('jt-ats');\n  var ATS=[63,100,125,160,200,250,315,400,500,630,800,1000,1250,1600,2000,2500,3200];\n  function nextAts(x){for(var i=0;i<ATS.length;i++){if(ATS[i]>=x)return ATS[i];}return null;}\n  function calc(){\n    var P=parseFloat(run.value),f=parseFloat(pf.value),mkw=parseFloat(motor.value),sm=parseFloat(start.value),\n        rv=(parseFloat(res.value)||0)\/100,dr=(parseFloat(der.value)||0)\/100;\n    if(!(P>0&&f>0)){gkvaEl.textContent='\u2014';gkwEl.textContent=govEl.textContent=atsEl.textContent='\u2014';return;}\n    if(dr>=0.9)dr=0.9;\n    var runKva=P\/f;\n    var mKva=(mkw>0)?mkw\/0.85:0;\n    var stepKva=(runKva-mKva)+mKva*sm;\n    var steady=runKva*(1+rv);\n    var govVal,govTxt;\n    if(steady>=stepKva){govVal=steady;govTxt='Running + reserve';}else{govVal=stepKva;govTxt='Largest motor start';}\n    var gkva=govVal\/(1-dr);\n    gkvaEl.textContent=Math.ceil(gkva);\n    gkwEl.textContent=Math.ceil(gkva*0.8)+' kW';\n    govEl.textContent=govTxt;\n    var amp=gkva*1000\/(Math.sqrt(3)*400);var a=nextAts(amp);\n    atsEl.textContent=(a?a+' A':'> 3200 A')+' ('+Math.round(amp)+' A FL)';\n  }\n  [run,pf,motor,start,res,der].forEach(function(el){el.addEventListener('input',calc);el.addEventListener('change',calc);});\n  $('jt-copy').addEventListener('click',function(){var b=$('jt-copy');var txt='Running load: '+run.value+' kW @ PF '+pf.value+'\\nLargest motor: '+motor.value+' kW, start '+start.options[start.selectedIndex].text+'\\nGenerator: '+gkvaEl.textContent+' kVA \/ '+gkwEl.textContent+'\\nGoverning case: '+govEl.textContent+'\\nATS: '+atsEl.textContent;navigator.clipboard.writeText(txt).then(function(){var o=b.textContent;b.textContent='Copied \u2713';setTimeout(function(){b.textContent=o;},1500);}).catch(function(){b.textContent='Press Ctrl+C';});});\n  calc();\n})();\n<\/script>\n<!-- ===== end block ===== -->\n\n","protected":false},"excerpt":{"rendered":"<p>Motor &amp; switching Generator Sizing Calculator for ATS Backup Estimate the standby generator kW and kVA from the diversified running load, the largest motor-starting step, a reserve margin, and site derating \u2014 then read the ATS rating that connects it. A planning starting point; confirm the transient voltage dip and step response with the generator [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1778,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1810","page","type-page","status-publish","hentry"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/pages\/1810","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/comments?post=1810"}],"version-history":[{"count":1,"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/pages\/1810\/revisions"}],"predecessor-version":[{"id":1811,"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/pages\/1810\/revisions\/1811"}],"up":[{"embeddable":true,"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/pages\/1778"}],"wp:attachment":[{"href":"https:\/\/jutrion.com\/pl\/wp-json\/wp\/v2\/media?parent=1810"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}