1.0Electrical Riddlehttps://electrical-riddle.com/enElectrical Riddlehttps://electrical-riddle.com/enrich600338<blockquote class="wp-embedded-content" data-secret="BHBQVOi1YK"><a href="https://electrical-riddle.com/en/forums/reply/1882/">Reply To: Transformer Riddle No.36 -ARC furance trafo capacity estimation</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://electrical-riddle.com/en/forums/reply/1882/embed/#?secret=BHBQVOi1YK" width="600" height="338" title="“Reply To: Transformer Riddle No.36 -ARC furance trafo capacity estimation” — Electrical Riddle" data-secret="BHBQVOi1YK" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script> /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); //# sourceURL=https://electrical-riddle.com/wp-includes/js/wp-embed.min.js </script> I think your calculation is very simple and suitable for electrical consumption estimation not for equipments sizing. As mentioned above the Steel arc furnace transformers operate under very severe conditions with regard to frequent over currents and overvoltages generated by short-circuits in the furnace and the operation of the HV circuit breaker (