{"id":7574,"date":"2026-01-05T09:17:37","date_gmt":"2026-01-05T09:17:37","guid":{"rendered":"https:\/\/daelimtransformer.com\/?p=7574"},"modified":"2026-09-02T15:55:21","modified_gmt":"2026-09-02T07:55:21","slug":"how-to-measure-the-load-loss-and-short-circuit-impedance-of-a-transformer%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/www.daelimtransformer.com\/de\/how-to-measure-the-load-loss-and-short-circuit-impedance-of-a-transformer.html","title":{"rendered":"Wie misst man den Lastverlust und den Kurzschlussimpedanz eines Transformators?"},"content":{"rendered":"<div id=\"contentMain\" class=\"article-content\">\n<p><!-- \u5de6\u53f3\u56fe\u6587--><!--\u6587\u5b57\u6a21\u5757--><\/p>\n<p><!-- \u8c46\u8150\u5757\u56fe\u6587\u4e0a\u4e0b--><\/p>\n<p><!-- \u5de6\u53f3\u56fe\u6587--><\/p>\n<p><!--\u6587\u5b57\u6a21\u5757--><\/p>\n<p><!-- \u8c46\u8150\u5757\u56fe\u6587\u4e0a\u4e0b--><\/p>\n<p><!-- \u5de6\u53f3\u56fe\u6587--><\/p>\n<p><!--\u6587\u5b57\u6a21\u5757--><\/p>\n<p><!-- \u8c46\u8150\u5757\u56fe\u6587\u4e0a\u4e0b--><\/p>\n<p><!-- \u5de6\u53f3\u56fe\u6587--><\/p>\n<p><!--\u6587\u5b57\u6a21\u5757--><\/p>\n<p><!-- \u8c46\u8150\u5757\u56fe\u6587\u4e0a\u4e0b--><\/p>\n<p><!-- \u5de6\u53f3\u56fe\u6587--><\/p>\n<p><!--\u6587\u5b57\u6a21\u5757--><\/p>\n<p><!-- \u8c46\u8150\u5757\u56fe\u6587\u4e0a\u4e0b--><\/p>\n<div class=\"row\">\n<div class=\"col-lg-12 article-content\">\n<h2 class=\"p\" style=\"text-align: left; margin-top: 7px; margin-bottom: 7px;\"><span class=\"ez-toc-section\" id=\"Procedure_for_Measurement\"><\/span><span style=\"font-size: 20px;\"><strong>Procedure for Measurement<\/strong><\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"Setup\"><\/span><strong><span style=\"font-size: 18px;\">Setup<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">Apply a sinusoidal voltage at the rated frequency to one winding.<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Short-circuit the other winding and leave any additional windings open.<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Current_Application\"><\/span><strong><span style=\"font-size: 18px;\">Current Application<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">Apply the corresponding rated current (or tap current).<\/span><\/li>\n<li><span style=\"font-size: 18px;\">If limited by test equipment, apply no less than 50% of the rated current (or tap current) and scale the measured load loss by the square of the ratio of the rated current to the test current.<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Temperature_Correction\"><\/span><strong><span style=\"font-size: 18px;\">Temperature Correction<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">Correct load loss and short-circuit impedance to the reference temperature of 75\u00b0C for oil-immersed transformers.<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Short-Circuit_Impedance\"><\/span><strong><span style=\"font-size: 18px;\">Short-Circuit Impedance<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">Expressed as a percentage. For three-winding transformers, use the maximum capacity as the reference.<\/span><\/li>\n<li><span style=\"font-size: 18px;\">For tap ranges exceeding \u00b15%, measure short-circuit impedance at the main tap and at two extreme taps.<\/span><\/li>\n<li><span style=\"font-size: 18px;\">In three-winding transformers, measure in three different pairs of windings and calculate respective short-circuit impedance and load loss.<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Standard_Deviations_for_Short-Circuit_Impedance\"><\/span><strong><span style=\"font-size: 18px;\">Standard Deviations for Short-Circuit Impedance<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">Two independent windings or first pair in a multi-winding transformer:<\/span>\n<ol>\n<li><span style=\"font-size: 18px;\">Main tapping: \u00b17.5% if impedance \u226510%, \u00b110% if impedance &lt;10%<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Other tapping: \u00b110% if impedance \u226510%, \u00b115% if impedance &lt;10%<\/span><\/li>\n<\/ol>\n<\/li>\n<li><span style=\"font-size: 18px;\">Autotransformer windings or second pair in a multi-winding transformer:<\/span>\n<ol>\n<li><span style=\"font-size: 18px;\">Main tapping: \u00b110%<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Other tapping: \u00b115%<\/span><\/li>\n<\/ol>\n<\/li>\n<li><span style=\"font-size: 18px;\">Other winding pairs:<\/span>\n<ol>\n<li><span style=\"font-size: 18px;\">\u00b115% (positive deviation can be increased by agreement)<\/span><\/li>\n<\/ol>\n<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Measurement_Method\"><\/span><strong><span style=\"font-size: 18px;\">Measurement Method<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">For three-phase transformers, apply the rated current from the high-voltage winding, short-circuiting the low-voltage and medium-voltage windings respectively.<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Use the medium-voltage winding to power the low-voltage winding and short-circuit it.<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Test_Instruments\"><\/span><strong><span style=\"font-size: 18px;\">Test Instruments<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">Voltmeter<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Ammeter<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Wattmeter<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Power analyzer<\/span><\/li>\n<li><span style=\"font-size: 18px;\">TMS580 measurement system<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Calculation_Formulas\"><\/span><strong><span style=\"font-size: 18px;\">Calculation Formulas<\/span><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span style=\"font-size: 18px;\">\u00a0<\/span>P<sub>kt<\/sub> = \u03a3 I<sup>2<\/sup>R<sub>t<\/sub> + P<sub>Ft<\/sub><\/p>\n<p>P<sub>k75<\/sub> = [P<sub>kt<\/sub> + (K<sup>2<\/sup> &#8211; 1)\u03a3 I<sup>2<\/sup>R<sub>t<\/sub>] \/ K<\/p>\n<p>u<sub>k<\/sub> = \u221a(u<sub>r<\/sub><sup>2<\/sup> + u<sub>x<\/sub><sup>2<\/sup>) (%)<\/p>\n<p>u<sub>rt<\/sub> = P<sub>kt<\/sub> \/ (10 S<sub>N<\/sub>) (%)<\/p>\n<p>u<sub>x<\/sub> = \u221a(u<sub>k<\/sub><sup>2<\/sup> &#8211; u<sub>rt<\/sub><sup>2<\/sup>) (%)<\/p>\n<p>u<sub>k75<\/sub> = \u221a(u<sub>r75<\/sub><sup>2<\/sup> + u<sub>x<\/sub><sup>2<\/sup>) (%)<\/p>\n<p>K = 310 \/ (235 + t)<\/p>\n<ul>\n<li><span style=\"font-size: 18px;\">Pkt: Measured load loss at t\u00b0C (W)<\/span><\/li>\n<li><span style=\"font-size: 18px;\">\u2211I\u00b2Rt: Resistance loss at t\u00b0C (W)<\/span><\/li>\n<li><span style=\"font-size: 18px;\">PFt: Additional loss at t\u00b0C (W)<\/span><\/li>\n<li><span style=\"font-size: 18px;\">Pk75: Load loss at 75\u00b0C (W)<\/span><\/li>\n<li><span style=\"font-size: 18px;\">SN: Rated capacity (kVA)<\/span><\/li>\n<li><span style=\"font-size: 18px;\">uk75: Short-circuit impedance at 75\u00b0C (%)<\/span><\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Notes\"><\/span><span style=\"color: #c0392b;\"><strong><span style=\"font-size: 18px;\">Notes:<\/span><\/strong><\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><span style=\"font-size: 18px;\">For high impedance test products, connect the ammeter (current transformer) after the voltmeter (voltage transformer).<\/span><\/li>\n<li><span style=\"font-size: 18px;\">For low impedance test products, connect the ammeter (current transformer) before the voltmeter (voltage transformer) to minimize impact.<\/span><\/li>\n<li><span style=\"font-size: 18px;\">In load tests of large transformers, ensure accuracy in the transformer selection and measurement loss correction due to the small power factor.<\/span><\/li>\n<li><span style=\"font-size: 18px;\">When calculating impedance, determine both the percentage of short-circuit impedance and the ohm value of each phase impedance. For delta connections, the phase impedance should refer to the equivalent star connection, not the internal phase impedance.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-size: 18px;\">By following these steps and considerations, accurate measurement of load loss and short-circuit impedance in transformers can be achieved, ensuring reliable performance and compliance with standards.<\/span><\/p>\n<p><span style=\"color: #2980b9;\"><strong><span style=\"font-size: 20px;\">More Resouces<\/span><\/strong><\/span><\/p>\n<p><strong><span style=\"font-size: 20px;\"><a href=\"https:\/\/www.daelimtransformer.com\/transformer-impedance.html\"><span style=\"color: #27ae60;\">The Impact of Impedance on Transformer Design<\/span><\/a><\/span><\/strong><\/p>\n<p><strong><span style=\"font-size: 20px;\"><a href=\"https:\/\/www.daelimtransformer.com\/losses-in-transformer-daelim.html\"><span style=\"color: #27ae60;\">Losses in Transformer: The Ultimate FAQs Guide<\/span><\/a><\/span><\/strong><\/p>\n<p><strong><span style=\"font-size: 20px;\"><a href=\"javascript:;\"><span style=\"color: #27ae60;\">Transformer Efficiency: The Ultimate FAQs Guide<\/span><\/a><\/span><\/strong><\/p>\n<p><strong><span style=\"font-size: 20px;\"><a href=\"https:\/\/www.daelimtransformer.com\/csa-c802:-minimum-efficiency-values-for-power-transformers.html\"><span style=\"color: #27ae60;\">CSA C802 For Minimum Efficiency Values For Power Transformers<\/span><\/a><\/span><\/strong><\/p>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Procedure for Measurement Setup Apply a sinusoidal voltage at the rated frequency to one winding. Short-circuit the other winding and leave any additional windings open. Current Application Apply the corresponding rated current (or tap current). If limited by test equipment, apply no less than 50% of the rated current (or tap current) and scale the [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[279],"tags":[],"class_list":["post-7574","post","type-post","status-publish","format-standard","hentry","category-articles-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/posts\/7574","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/comments?post=7574"}],"version-history":[{"count":1,"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/posts\/7574\/revisions"}],"predecessor-version":[{"id":13272,"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/posts\/7574\/revisions\/13272"}],"wp:attachment":[{"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/media?parent=7574"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/categories?post=7574"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.daelimtransformer.com\/de\/wp-json\/wp\/v2\/tags?post=7574"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}