{"id":20378,"date":"2026-10-30T10:11:46","date_gmt":"2026-10-30T02:11:46","guid":{"rendered":"https:\/\/www.wehopower.com\/news\/s145-ssr-off-state-leakage\/"},"modified":"2026-10-30T10:11:46","modified_gmt":"2026-10-30T02:11:46","slug":"s145-ssr-off-state-leakage","status":"publish","type":"news","link":"https:\/\/www.wehopower.com\/ur\/news\/s145-ssr-off-state-leakage\/","title":{"rendered":"SSR Off-State Leakage and a Switching Supply: Define the Inactive-State Check"},"content":{"rendered":"<div class=\"weho-blog-content\">\n<p><strong>When an SSR controls a switching power supply, specify what the system must do after the OFF command and verify the exact SSR, supply and load together.<\/strong> A semiconductor switch can pass off-state leakage current, while a supply can also retain stored charge. Those effects need different evidence.<\/p>\n<p>For an OEM selecting the WEHO S-145-24, the useful deliverable is an inactive-state acceptance record: what is commanded off, what remains energized, what the load is allowed to do, and how the result is verified by the qualified test team.<\/p>\n<nav class=\"toc\" aria-label=\"Article contents\">\n<p>In this article<\/p>\n<ol>\n<li><a href=\"#two-sides\">Identify which side of the supply the SSR switches<\/a><\/li>\n<li><a href=\"#causes\">Separate three explanations for an apparently live output<\/a><\/li>\n<li><a href=\"#acceptance\">Write the inactive-state requirement before the test<\/a><\/li>\n<li><a href=\"#decision-example\">Turn a symptom into a procurement decision<\/a><\/li>\n<li><a href=\"#release\">Keep functional OFF and service isolation as separate release items<\/a><\/li>\n<\/ol>\n<\/nav>\n<section id=\"two-sides\">\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\/s145-ssr-off-state-leakage\/#Identify_which_side_of_the_supply_the_SSR_switches\" >Identify which side of the supply the SSR switches<\/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\/s145-ssr-off-state-leakage\/#Separate_three_explanations_for_an_apparently_live_output\" >Separate three explanations for an apparently live output<\/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\/s145-ssr-off-state-leakage\/#Write_the_inactive-state_requirement_before_the_test\" >Write the inactive-state requirement before the test<\/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\/s145-ssr-off-state-leakage\/#Turn_a_symptom_into_a_procurement_decision\" >Turn a symptom into a procurement decision<\/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\/s145-ssr-off-state-leakage\/#Keep_functional_OFF_and_service_isolation_as_separate_release_items\" >Keep functional OFF and service isolation as separate release items<\/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\/s145-ssr-off-state-leakage\/#Use_the_project_record\" >Use the project record<\/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\/s145-ssr-off-state-leakage\/#Discuss_the_S-145-24_application_boundary\" >Discuss the S-145-24 application boundary<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.wehopower.com\/ur\/news\/s145-ssr-off-state-leakage\/#Sources_and_further_reading\" >Sources and further reading<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"Identify_which_side_of_the_supply_the_SSR_switches\"><\/span>Identify which side of the supply the SSR switches<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Start with the released circuit description. An AC-output SSR controlling the supply\u2019s AC input and a DC-output SSR switching a DC load are different applications. Do not transfer the leakage figure, minimum-load requirement or switching behavior from one SSR type to the other.<\/p>\n<p>The <a href=\"https:\/\/www.wehopower.com\/ur\/product\/s-145w-series-normal-single-switching-power-supply\/\">WEHO S-145-24 product information<\/a> and <a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2025\/07\/S-145.pdf\">S-145 specification sheet<\/a> identify a 24 V switching-supply option. They do not establish compatibility with an unspecified SSR, an off-state load-release limit or a guaranteed output-discharge interval.<\/p>\n<p>Record the SSR manufacturer and exact suffix, the switched side, the permitted input source and the downstream load. For the S-145 family, the published selectable input range also means that input configuration must be checked against the supplied version; an SSR cannot correct an incorrect input selection.<\/p>\n<figure class=\"figure\" id=\"figure-diagram\"><picture><source media=\"(max-width: 600px)\" srcset=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/decision-map-mobile-7.svg\" width=\"480\" height=\"1390\" type=\"image\/svg+xml\"><img loading=\"lazy\" src=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/decision-map-7.svg\" alt=\"SSR Off-State Leakage and a Switching Supply: Define the Inactive-State Check  title=\" width=\"1200\" height=\"740\" decoding=\"async\" ssr off-state leakage and switching supply: define the inactive-state check title =\"\"><\/picture><figcaption>OFF command and inactive behavior are separate checks. A conceptual decision record separates commanded OFF, SSR leakage evidence, retained or external energy and the required load outcome. <a class=\"original-link\" href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/decision-map-7.svg\">View original image<\/a><\/figcaption><\/figure>\n<\/section>\n<section id=\"causes\">\n<h2><span class=\"ez-toc-section\" id=\"Separate_three_explanations_for_an_apparently_live_output\"><\/span>Separate three explanations for an apparently live output<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><a href=\"https:\/\/www.ia.omron.com\/support\/guide\/31\/further_information.html\" target=\"_blank\" rel=\"noopener\">OMRON\u2019s SSR guide<\/a> defines off-state leakage as current through the SSR output while the output is off and a specified load voltage is applied. Its <a href=\"https:\/\/www.ia.omron.com\/support\/faq\/answer\/18\/faq02155\/index.html\" target=\"_blank\" rel=\"noopener\">OFF-state troubleshooting guidance<\/a> also distinguishes input-side causes from output-side leakage that may prevent a load from releasing.<\/p>\n<p>That evidence explains why an OFF command needs a system-level check. It does not prove the cause of a particular reading in your panel. Have the test engineer classify the observation using the actual circuit and appropriate instrumentation.<\/p>\n<div class=\"table-wrap\">\n<table>\n<thead>\n<tr>\n<th scope=\"col\">Possible condition<\/th>\n<th scope=\"col\">Question for the qualified test team<\/th>\n<th scope=\"col\">Evidence that helps separate it<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<th scope=\"row\">SSR off-state leakage<\/th>\n<td>Does the specified SSR leakage interact with this supply input or load?<\/td>\n<td>SSR leakage conditions, minimum-load data and controlled comparison approved by the test team.<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Retained charge<\/th>\n<td>Is the observed condition a time-dependent effect after source removal?<\/td>\n<td>Applicable discharge information and a recorded observation interval.<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Another energy path<\/th>\n<td>Can a separate supply or powered interface maintain the observed circuit?<\/td>\n<td>Released schematic and interface-source inventory.<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Command or configuration issue<\/th>\n<td>Did the intended OFF state actually reach the correct SSR input?<\/td>\n<td>Controller state and SSR input specification, recorded independently of the load result.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>A voltage reported by one instrument does not, on its own, quantify the current available to operate a load. Record the measurement method with the result; avoid treating a high-impedance reading as either proof of useful power or proof of a harmless condition.<\/p>\n<\/section>\n<section id=\"acceptance\">\n<h2><span class=\"ez-toc-section\" id=\"Write_the_inactive-state_requirement_before_the_test\"><\/span>Write the inactive-state requirement before the test<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Describe a functional outcome that the equipment owner can accept. A controller may need to remain powered while an actuator must stop. A status lamp that glows faintly can be a different issue from a device that periodically restarts. These observations should not share a single checkbox labeled \u201cOFF works.\u201d<\/p>\n<p>For each required mode, record the command state, source condition, connected load, observation period and required load behavior. The test team should define the suitable instrument, measurement point and interpretation. Keep personnel-safety isolation requirements separate from this functional acceptance record.<\/p>\n<p>Check the least-loaded permitted configuration as well as normal operation when the SSR documentation makes minimum load relevant. Include authorized standby modes and the intended restart sequence. Do not create a test condition outside the supply, SSR or equipment ratings simply to make the symptom disappear.<\/p>\n<p>The S-145 sheet\u2019s hold-up-time entry concerns functional output continuity under stated conditions. It is not a maximum time to safe touch, nor an assurance that every connected load has discharged.<\/p>\n<\/section>\n<section id=\"decision-example\">\n<h2><span class=\"ez-toc-section\" id=\"Turn_a_symptom_into_a_procurement_decision\"><\/span>Turn a symptom into a procurement decision<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>In a hypothetical cabinet, a switched supply feeds a small controller. The requirement says that the controller must remain inactive after the OFF command until a deliberate restart. During qualification, the team would record whether the controller stays off, remains partially active or cycles through startup. No measurement or outcome is assumed here.<\/p>\n<p>If the system does not meet the requirement, first preserve the configuration and trace the relevant cause. Request the SSR\u2019s off-state specification and the supply\/load behavior needed to evaluate alternatives. A different switching device or architecture may be appropriate, but its selection requires the actual circuit evidence.<\/p>\n<p>Do not select a bleeder resistor by copying a value from another installation. Any proposed remedy needs its own voltage, power, thermal, insulation and failure review, plus confirmation that it does not defeat the intended inactive state. Manufacturer advice for one SSR and load is not a universal add-on instruction.<\/p>\n<\/section>\n<section id=\"release\">\n<h2><span class=\"ez-toc-section\" id=\"Keep_functional_OFF_and_service_isolation_as_separate_release_items\"><\/span>Keep functional OFF and service isolation as separate release items<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>OMRON\u2019s SSR guide discusses semiconductor short-circuit failure and the need for an appropriate fail-safe design. Accordingly, a functional OFF test cannot establish that an SSR is a service disconnect or a safety-rated isolation function.<\/p>\n<p>Release the combination only when the specified inactive behavior is met, the record identifies the tested versions, and any remedy is incorporated into the approved design. Preserve unresolved observations as engineering actions, rather than approving the assembly because the supply\u2019s output-current rating is adequate.<\/p>\n<\/section>\n<section id=\"project-record\">\n<h2><span class=\"ez-toc-section\" id=\"Use_the_project_record\"><\/span>Use the project record<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><a href=\"\/ur\/acceptance-record.html\/\">Open the blank SSR and Switching Supply \u2014 Inactive-State Record<\/a> to record your conditions, evidence and decisions. The worksheet contains no pre-approved result.<\/p>\n<\/section>\n<section class=\"cta\" id=\"project-review\">\n<h2><span class=\"ez-toc-section\" id=\"Discuss_the_S-145-24_application_boundary\"><\/span>Discuss the S-145-24 application boundary<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Send WEHO the exact SSR model, whether it switches the AC input or a DC load, the load\u2019s standby behavior and your required inactive state. Request the applicable S-145-24 documents before qualifying the complete circuit.<\/p>\n<p><a href=\"https:\/\/www.wehopower.com\/ur\/contact\/\">Contact WEHO about S-145-24 application information<\/a><\/p>\n<\/section>\n<section class=\"sources\" id=\"sources\">\n<h2><span class=\"ez-toc-section\" id=\"Sources_and_further_reading\"><\/span>Sources and further reading<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ol>\n<li><a href=\"https:\/\/www.wehopower.com\/ur\/product\/s-145w-series-normal-single-switching-power-supply\/\">WEHO S-145 switching supply product information<\/a><\/li>\n<li><a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2025\/07\/S-145.pdf\">WEHO S-145 specification sheet<\/a><\/li>\n<li><a href=\"https:\/\/www.ia.omron.com\/support\/guide\/31\/further_information.html\" target=\"_blank\" rel=\"noopener\">OMRON Further Information of Solid-state Relays<\/a><\/li>\n<li><a href=\"https:\/\/www.ia.omron.com\/support\/faq\/answer\/18\/faq02155\/index.html\" target=\"_blank\" rel=\"noopener\">OMRON FAQ02155 \u2014 SSR does not turn OFF<\/a><\/li>\n<\/ol>\n<\/section>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>An SSR OFF command does not prove zero current or electrical isolation. Define the expected supply and load behavior, then qualify the exact combination.<\/p>","protected":false},"author":2,"featured_media":20365,"parent":0,"menu_order":21,"comment_status":"","ping_status":"","template":"","format":"standard","meta":{"_acf_changed":false,"_joinchat":[],"footnotes":""},"news_category":[284],"class_list":["post-20378","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\/20378","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=20378"}],"version-history":[{"count":0,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news\/20378\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/media\/20365"}],"wp:attachment":[{"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/media?parent=20378"}],"wp:term":[{"taxonomy":"news_category","embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news_category?post=20378"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}