{"id":20272,"date":"2026-10-28T14:36:20","date_gmt":"2026-10-28T06:36:20","guid":{"rendered":"https:\/\/www.wehopower.com\/news\/power-supply-ovc-ii-iii-installation-evidence\/"},"modified":"2026-10-28T14:36:20","modified_gmt":"2026-10-28T06:36:20","slug":"power-supply-ovc-ii-iii-installation-evidence","status":"publish","type":"news","link":"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/","title":{"rendered":"OVC II or III for a Power Supply? Match the Installation and Insulation Evidence"},"content":{"rendered":"<div class=\"weho-geo-content weho-geo09\">\n<p class=\"lead\"><strong>Choose between OVC II and OVC III by reviewing the actual supply interface and applicable equipment requirements, then matching them to exact-model insulation and installation evidence.<\/strong> A DIN rail, metal enclosure or input-voltage range does not make that decision. If the installation conditions exceed the documented basis, obtain an accepted integration solution before releasing the power supply.<\/p>\n<figure id=\"figure-product-hero\" class=\"product-hero\"><a class=\"hero-image-link\" href=\"https:\/\/www.wehopower.com\/ur\/product\/silm-size-hdr-150-150w-din-rail-switching-power-supply\/\" aria-label=\"View HDR-150-24 product details\"><img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/product-scene-5.jpg\" width=\"1254\" height=\"1254\" alt=\"OVC II or III for a Power Supply? Match the Installation and Insulation Evidence  title=\" ovc ii or iii for power match the installation and insulation evidence title =\"\"><\/a><figcaption>WEHO HDR-150-24 in a cabinet-preparation illustration. The product and rail come from the accurate source photo; the AI-assisted environment does not establish an overvoltage category. <a href=\"https:\/\/www.wehopower.com\/ur\/product\/silm-size-hdr-150-150w-din-rail-switching-power-supply\/\">HDR-150-24 product details<\/a>. <a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/product-scene-5.jpg\">View full-size illustration<\/a>.<\/figcaption><\/figure>\n<p>For OEM electrical and procurement teams, the useful output is a qualification record: where the supply connects, which conditions apply, what the candidate\u2019s evidence covers and which gaps remain. This article does not assign an OVC to a WEHO model or replace the responsible safety engineer\u2019s assessment.<\/p>\n<nav class=\"toc\" aria-label=\"Table of contents\"><strong>In this guide<\/strong><\/p>\n<ol>\n<li><a href=\"#meaning\">What II and III describe<\/a><\/li>\n<li><a href=\"#interface\">Define the source and input interface<\/a><\/li>\n<li><a href=\"#model\">Read a category claim with its conditions<\/a><\/li>\n<li><a href=\"#worksheet\">Compare the installation and candidate file<\/a><\/li>\n<li><a href=\"#protection\">Resolve external-protection conditions explicitly<\/a><\/li>\n<li><a href=\"#release\">Keep OVC separate from other test claims<\/a><\/li>\n<\/ol>\n<\/nav>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_86 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">\u0645\u0646\u062f\u0631\u062c\u0627\u062a \u06a9\u0627 \u062c\u062f\u0648\u0644<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">\u0679\u0648\u06af\u0644 \u06a9\u0631\u06cc\u06ba\u06d4<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewbox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewbox=\"0 0 24 24\" version=\"1.2\" baseprofile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/#What_II_and_III_describe\" >What II and III describe<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/#Define_the_source_and_input_interface\" >Define the source and input interface<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/#Read_a_category_claim_with_its_conditions\" >Read a category claim with its conditions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/#Compare_the_installation_and_candidate_file\" >Compare the installation and candidate file<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/#Resolve_external-protection_conditions_explicitly\" >Resolve external-protection conditions explicitly<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/#Keep_OVC_separate_from_other_test_claims\" >Keep OVC separate from other test claims<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-ovc-ii-iii-installation-evidence\/#Match_the_candidate_to_your_installation\" >Match the candidate to your installation<\/a><\/li><\/ul><\/nav><\/div>\n<h2 id=\"meaning\"><span class=\"ez-toc-section\" id=\"What_II_and_III_describe\"><\/span>What II and III describe<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Overvoltage categories characterize expected transient conditions at an electrical interface. TDK-Lambda\u2019s <a href=\"https:\/\/www.us.lambda.tdk.com\/resources\/blogs\/20171107.html\" target=\"_blank\" rel=\"noopener\">OVC explanation<\/a> describes Category III in the context of fixed installations and Category II in the context of energy-consuming equipment supplied from the fixed installation. These examples help frame the question; they do not classify every control cabinet or hard-wired device without further review.<\/p>\n<p>Read the category together with the supply-system voltage and applicable standard. \u201cOVC III\u201d without its associated conditions is incomplete purchasing information. Categories also should not be used as a general quality ranking: the task is to satisfy the actual installation requirement, not to choose the largest Roman numeral appearing in a brochure.<\/p>\n<p>The IEC catalogue now lists <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/107319\" target=\"_blank\" rel=\"noopener\">IEC 60664-1:2020+AMD1:2025<\/a> as an insulation-coordination publication addressing clearance, creepage and solid-insulation criteria within its stated scope. Check which edition and amendments the project actually requires. A newer catalogue entry does not automatically change a product\u2019s existing assessment or the contractual basis of an installation.<\/p>\n<h2 id=\"interface\"><span class=\"ez-toc-section\" id=\"Define_the_source_and_input_interface\"><\/span>Define the source and input interface<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Begin with a system drawing or controlled installation description, not a photograph of the cabinet. Identify the source feeding the candidate, the point of connection, the system voltage and the relevant circuit classification. State whether the question concerns an AC-mains interface, a DC distribution interface or an isolated external circuit.<\/p>\n<p>This distinction matters when apparently similar questions arise. In its <a href=\"https:\/\/www.ul.com\/resources\/iec-62368-1-ask-engineers-question-and-answer-page\" target=\"_blank\" rel=\"noopener\">IEC 62368-1 engineering FAQ<\/a>, UL discusses an outdoor DC\/PoE case by first identifying the circuit under IEC 62368-1:2023. The discussion also distinguishes an external-circuit transient assessment from an assumed mains category. It is a specific product-standard example, not an exemption for every DC-powered industrial product.<\/p>\n<p>Have the responsible project reviewer establish the required classification and its basis. Record any installation restrictions, environmental assumptions and conditions on upstream protection. The terms \u201cindustrial,\u201d \u201coutdoor\u201d and \u201cpanel-mounted\u201d do not provide that complete record.<\/p>\n<h2 id=\"model\"><span class=\"ez-toc-section\" id=\"Read_a_category_claim_with_its_conditions\"><\/span>Read a category claim with its conditions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Ask the supplier to identify the complete model and revision, the applicable assessment or report, the input interface and the conditions under which the claimed suitability applies. Keep installation instructions with the assessment. A family-level statement may be useful, but it needs a traceable explanation of coverage for the ordered suffix and construction.<\/p>\n<figure id=\"figure-product-original\" class=\"product-detail\"><a class=\"detail-image-link\" href=\"https:\/\/www.wehopower.com\/ur\/product\/silm-size-hdr-150-150w-din-rail-switching-power-supply\/\" aria-label=\"View HDR-150-24 product details\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/product-original-6.jpg\" width=\"1000\" height=\"1000\" alt=\"OVC II or III for a Power Supply? Match the Installation and Insulation Evidence  title=\" ovc ii or iii for power match the installation and insulation evidence title =\"\"><\/a><figcaption>WEHO HDR-150-24 original photograph for model identification. Its enclosure, DIN rail and visible markings do not establish the applicable OVC or internal insulation assessment. <a href=\"https:\/\/www.wehopower.com\/ur\/product\/silm-size-hdr-150-150w-din-rail-switching-power-supply\/\">HDR-150-24 product details<\/a>. <a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/product-original-6.jpg\">View original product photo<\/a>.<\/figcaption><\/figure>\n<p>The HDR-150-24 shown here is an accurate identity reference. Its <a href=\"\/wp-content\/uploads\/weho-geo-2026-10-26\/documents\/HDR-1502--1477b98357cf.pdf\">WEHO specification<\/a> helps identify the model and physical arrangement. No model-specific OVC assessment has been established for this article. A listed withstand-voltage value, output-protection entry or a visible mark cannot be substituted for that missing evidence.<\/p>\n<figure id=\"figure-evidence\"><a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/technical-7.svg\" aria-label=\"Open full-size evidence diagram\"><picture><source media=\"(max-width:560px)\" srcset=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/technical-mobile-7.svg\" width=\"650\" height=\"1000\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/technical-7.svg\" width=\"1200\" height=\"545\" alt=\"OVC II or III for a Power Supply? Match the Installation and Insulation Evidence  title=\" ovc ii or iii for power match the installation and insulation evidence title =\"\"><\/picture><\/a><figcaption>Proposed qualification workflow. The installation requirement and the supplier\u2019s model evidence must be compared; the diagram assigns no category or impulse value. <a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/technical-7.svg\">View full-size diagram<\/a>.<\/figcaption><\/figure>\n<h2 id=\"worksheet\"><span class=\"ez-toc-section\" id=\"Compare_the_installation_and_candidate_file\"><\/span>Compare the installation and candidate file<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Use a side-by-side qualification worksheet. Each unresolved difference should produce a bounded question for the supplier and the equipment reviewer, rather than an automatic \u201capproved\u201d or a guessed category.<\/p>\n<p class=\"table-hint\">On small screens, scroll sideways to compare each qualification field.<\/p>\n<div class=\"table-scroll\" tabindex=\"0\" role=\"region\" aria-label=\"OVC installation and model qualification worksheet\">\n<table>\n<thead>\n<tr>\n<th>Field<\/th>\n<th>Installation record<\/th>\n<th>Evidence to obtain from the candidate file<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Source and interface<\/td>\n<td>Actual AC or DC source, circuit role and connection point.<\/td>\n<td>Assessed input interface and the model\u2019s permitted use conditions.<\/td>\n<\/tr>\n<tr>\n<td>Voltage basis<\/td>\n<td>Applicable system-voltage information, including the reference needed by the chosen method.<\/td>\n<td>Corresponding assessment basis, not only a broad operating-input range.<\/td>\n<\/tr>\n<tr>\n<td>Category or transient requirement<\/td>\n<td>Requirement selected under the applicable product and installation rules.<\/td>\n<td>Explicit model coverage and the conditions attached to that statement.<\/td>\n<\/tr>\n<tr>\n<td>Environment<\/td>\n<td>Relevant altitude, pollution and enclosure conditions established for the equipment.<\/td>\n<td>Matching limits and restrictions from the applicable insulation and installation record.<\/td>\n<\/tr>\n<tr>\n<td>Additional protection<\/td>\n<td>Specified protective arrangement and its controlled configuration, if needed.<\/td>\n<td>Evidence that the exact arrangement satisfies the relevant assessment, including installation requirements.<\/td>\n<\/tr>\n<tr>\n<td>Release and change control<\/td>\n<td>Named responsible reviewer and accepted equipment configuration.<\/td>\n<td>Model\/revision mapping, resolved questions and rules for later substitutions.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>For example, a hypothetical buyer receives an OVC II statement for a supply while the project reviewer has specified conditions associated with OVC III at the intended connection. Matching output voltage and mechanical fit does not close the gap. The buyer should request a documented suitable candidate or a reviewed integration arrangement, then retain the resulting decision. This is a document-review example, not a category assignment to the pictured HDR unit.<\/p>\n<h2 id=\"protection\"><span class=\"ez-toc-section\" id=\"Resolve_external-protection_conditions_explicitly\"><\/span>Resolve external-protection conditions explicitly<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>If additional transient protection is proposed, define the actual arrangement and ask what evidence demonstrates its suitability under the governing requirements. An arbitrary surge-protective device added to a drawing does not automatically change the accepted category or prove the necessary insulation conditions at the supply interface.<\/p>\n<p>Check the protection\u2019s documented coordination, connection and installation conditions with the responsible designer. Preserve any restrictions in the equipment instructions and BOM. The details depend on the project and assessment method; this article does not provide a universal SPD selection or wiring modification.<\/p>\n<p>A supplier\u2019s recommendation should identify what it covers and which equipment-level review remains. If the proposed configuration relies on an unspecified device, an undocumented source or an unreviewed construction change, keep the relevant qualification question open.<\/p>\n<h2 id=\"release\"><span class=\"ez-toc-section\" id=\"Keep_OVC_separate_from_other_test_claims\"><\/span>Keep OVC separate from other test claims<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Output overvoltage protection concerns the regulated output\u2019s protective response. It is not the input-interface overvoltage-category assessment. Similarly, a dielectric-withstand result or an EMC surge-immunity result answers a different question; do not translate one of those numbers into an OVC without the applicable assessment.<\/p>\n<p>The separate <a href=\"https:\/\/www.wehopower.com\/ur\/news\/power-supply-creepage-and-clearance-ask-for-the-insulation-coordination-record\/\">creepage and clearance evidence guide<\/a> explains how to request construction-specific insulation records. Here, the purchasing decision comes first: establish the installation\u2019s conditions, then identify which candidate evidence applies. Do not estimate internal spacing from the product photograph or assume that changing the enclosure closes the assessment.<\/p>\n<p>Before approving a substitute, compare its exact model, construction and installation conditions with the accepted file. Preserve the reviewer\u2019s disposition and any outstanding restriction. A different supply with the same DC output needs its own coverage check.<\/p>\n<aside class=\"article-cta\" aria-label=\"Request WEHO installation evidence\">\n<h2><span class=\"ez-toc-section\" id=\"Match_the_candidate_to_your_installation\"><\/span>Match the candidate to your installation<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Send WEHO the intended supply interface, system-voltage information, target market, applicable standard and required installation conditions. Request the available exact-model documentation and have the responsible equipment reviewer assess its coverage.<\/p>\n<p><a class=\"button\" href=\"https:\/\/www.wehopower.com\/ur\/contact\/\">Request model-specific installation evidence<\/a><\/aside>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Match a power supply\u2019s OVC evidence to the actual input interface, system voltage and installation conditions before approving an OEM equipment design.<\/p>","protected":false},"author":2,"featured_media":20257,"parent":0,"menu_order":33,"comment_status":"","ping_status":"","template":"","format":"standard","meta":{"_acf_changed":false,"_joinchat":[],"footnotes":""},"news_category":[284],"class_list":["post-20272","news","type-news","status-publish","format-standard","has-post-thumbnail","hentry","news_category-product-articles","entry"],"acf":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news\/20272","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/types\/news"}],"author":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/comments?post=20272"}],"version-history":[{"count":0,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news\/20272\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/media\/20257"}],"wp:attachment":[{"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/media?parent=20272"}],"wp:term":[{"taxonomy":"news_category","embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news_category?post=20272"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}