{"id":20165,"date":"2026-10-27T14:03:35","date_gmt":"2026-10-27T06:03:35","guid":{"rendered":"https:\/\/www.wehopower.com\/news\/electronic-load-power-supply-testing-cc-cr-cp-cv\/"},"modified":"2026-10-27T14:14:28","modified_gmt":"2026-10-27T06:14:28","slug":"electronic-load-power-supply-testing-cc-cr-cp-cv","status":"publish","type":"news","link":"https:\/\/www.wehopower.com\/ur\/news\/electronic-load-power-supply-testing-cc-cr-cp-cv\/","title":{"rendered":"Electronic Loads for Power Supply Testing: Choose CC, CR, CP or CV Mode"},"content":{"rendered":"<div class=\"weho-blog-content\">\n<p>The right electronic load for testing a power supply is the one that reproduces the behavior relevant to your decision. Constant current, resistance, power and voltage are different control laws. Selecting a convenient front-panel mode can change the stress applied to the supply and the conclusion drawn from a test.<\/p>\n<details class=\"article-toc\" open>\n<summary>On this page<\/summary>\n<ol class=\"toc-list\">\n<li><a href=\"#match-the-mode-to-the-question\">Match the mode to the question<\/a><\/li>\n<li><a href=\"#see-how-three-modes-diverge-during-a-voltage-dip\">See how three modes diverge during a voltage dip<\/a><\/li>\n<li><a href=\"#use-cv-as-a-sink-with-the-correct-source\">Use CV as a sink, with the correct source<\/a><\/li>\n<li><a href=\"#check-the-full-operating-envelope\">Check the full operating envelope<\/a><\/li>\n<li><a href=\"#keep-a-record-that-makes-the-result-reusable\">Keep a record that makes the result reusable<\/a><\/li>\n<\/ol>\n<\/details>\n<p>For an OEM validation engineer, start with a short description of the real load: what does it demand when the supply voltage changes, and what happens during startup or a transient? Choose the electronic-load mode from that behavior, then verify that the instrument can reproduce it over the required operating range.<\/p>\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\/electronic-load-power-supply-testing-cc-cr-cp-cv\/#Match_the_mode_to_the_question\" >Match the mode to the question<\/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\/electronic-load-power-supply-testing-cc-cr-cp-cv\/#See_how_three_modes_diverge_during_a_voltage_dip\" >See how three modes diverge during a voltage dip<\/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\/electronic-load-power-supply-testing-cc-cr-cp-cv\/#Use_CV_as_a_sink_with_the_correct_source\" >Use CV as a sink, with the correct source<\/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\/electronic-load-power-supply-testing-cc-cr-cp-cv\/#Check_the_full_operating_envelope\" >Check the full operating envelope<\/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\/electronic-load-power-supply-testing-cc-cr-cp-cv\/#Keep_a_record_that_makes_the_result_reusable\" >Keep a record that makes the result reusable<\/a><\/li><\/ul><\/nav><\/div>\n<h2 id=\"match-the-mode-to-the-question\"><span class=\"ez-toc-section\" id=\"Match_the_mode_to_the_question\"><\/span>Match the mode to the question<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><a href=\"https:\/\/www.keysight.com\/us\/en\/products\/dc-electronic-loads.html\" target=\"_blank\" rel=\"noopener\">Keysight\u2019s electronic-load overview<\/a> identifies the four common modes: constant current (CC), constant resistance (CR), constant power (CP) and constant voltage (CV). The controlled quantity is the first selection criterion. A mode\u2019s name does not guarantee operation outside the instrument\u2019s specified envelope.<\/p>\n<div class=\"weho-table-wrap\" tabindex=\"0\" role=\"region\" aria-label=\"Scrollable article table\">\n<table>\n<thead>\n<tr>\n<th>Mode<\/th>\n<th>What the load tries to maintain<\/th>\n<th>A useful test question<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>CC<\/td>\n<td>A programmed current<\/td>\n<td>Can the supply regulate at specified current levels or load steps?<\/td>\n<\/tr>\n<tr>\n<td>CR<\/td>\n<td>A programmed resistance; current changes with voltage<\/td>\n<td>How does the source behave with a resistive demand?<\/td>\n<\/tr>\n<tr>\n<td>CP<\/td>\n<td>A programmed power; current increases as voltage falls<\/td>\n<td>How does the source respond to a downstream load approximating constant input power?<\/td>\n<\/tr>\n<tr>\n<td>CV<\/td>\n<td>A terminal voltage by adjusting the current it sinks<\/td>\n<td>How does a current-regulated source behave against a controlled terminal voltage?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>A load can represent one part of a device\u2019s behavior without reproducing all of it. A downstream converter may look approximately constant-power within its regulation range, but its startup threshold, input capacitance, current limit and shutdown behavior remain separate characteristics. A single CP setting does not reproduce that complete converter.<\/p>\n<p>The <a href=\"https:\/\/www.wehopower.com\/ur\/product\/ndr-dinrail-240w-ac-to-dc-single-output-switching-power-supply\/\">WEHO NDR-240-24<\/a> illustrates the source side of this decision: its public <a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2021\/11\/NDR-240.pdf\">NDR-240 specification<\/a> lists 24 V and an output-current range of 0\u201310 A for this variant. Choose the load instrument against the required test points and its own operating envelope. The NDR-240-24 is a power source, and the 48 W mode comparison below remains hypothetical.<\/p>\n<figure class=\"product-reference\" id=\"figure-product\"><a class=\"product-image\" href=\"https:\/\/www.wehopower.com\/ur\/product\/ndr-dinrail-240w-ac-to-dc-single-output-switching-power-supply\/\" aria-label=\"NDR-240-24 product details\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/48-product-display.svg\" width=\"600\" height=\"680\" alt=\"Electronic Loads for Power Supply Testing: Choose CC, CR, CP or CV Mode  title=\" electronic loads for power supply testing: choose cp or cv mode title =\"\"><\/a><figcaption>NDR-240-24 AC-DC source appearance reference. This is not an electronic load or a record of completed load testing.<\/figcaption><div class=\"image-actions\"><a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/48-product-original.jpg\">View unchanged original photograph<\/a><a href=\"https:\/\/www.wehopower.com\/ur\/product\/ndr-dinrail-240w-ac-to-dc-single-output-switching-power-supply\/\">NDR-240-24 product details<\/a><a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2021\/11\/NDR-240.pdf\">NDR-240-24 documentation<\/a><\/div>\n<\/figure>\n<h2 id=\"see-how-three-modes-diverge-during-a-voltage-dip\"><span class=\"ez-toc-section\" id=\"See_how_three_modes_diverge_during_a_voltage_dip\"><\/span>See how three modes diverge during a voltage dip<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Suppose three hypothetical tests begin at 24 V and 48 W. Set CC to 2 A, CR to 12 \u03a9, and CP to 48 W. At the starting voltage, all three demand the same current and power. Their demands diverge if the source voltage falls to 18 V.<\/p>\n<div class=\"weho-table-wrap\" tabindex=\"0\" role=\"region\" aria-label=\"Scrollable article table\">\n<table>\n<thead>\n<tr>\n<th>Programmed mode<\/th>\n<th>Current at 24 V<\/th>\n<th>Current at 18 V<\/th>\n<th>Power at 18 V<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>CC: 2 A<\/td>\n<td>2.00 A<\/td>\n<td>2.00 A<\/td>\n<td>36 W<\/td>\n<\/tr>\n<tr>\n<td>CR: 12 \u03a9<\/td>\n<td>2.00 A<\/td>\n<td>1.50 A<\/td>\n<td>27 W<\/td>\n<\/tr>\n<tr>\n<td>CP: 48 W<\/td>\n<td>2.00 A<\/td>\n<td>2.67 A, rounded<\/td>\n<td>48 W<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>These values follow I = V\/R and P = VI, assuming each mode remains in control. The CP demand is 48\/18 = 2.666\u2026 A. If the load\u2019s current limit or low-voltage boundary prevents that current, the actual test no longer represents ideal 48 W operation. Record the limitation instead of reporting the setpoint as the achieved load. For startup work, record any programmed load-on voltage and the instrument\u2019s actual low-voltage behavior.<\/p>\n<figure class=\"article-relation concept-diagram\" id=\"figure-mode-response\"><a href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/48-mode-response.svg\" aria-label=\"Open full-size Same starting power, different response diagram\"><picture><source media=\"(max-width:640px)\" srcset=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/48-mode-response-mobile.svg\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/48-mode-response.svg\" width=\"1200\" height=\"485\" alt=\"Electronic Loads for Power Supply Testing: Choose CC, CR, CP or CV Mode  title=\" electronic loads for power supply testing: choose cp or cv mode title =\"\"><\/picture><\/a><figcaption>Hypothetical steady-state comparison: all three modes begin at 24 V and 48 W. The 18 V results assume the load remains inside its operating envelope; these are calculations, not measured supply traces.<\/figcaption><a class=\"diagram-original\" href=\"https:\/\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/48-mode-response.svg\">Open full-size diagram<\/a><\/figure>\n<p>This comparison explains why a supply that passes a resistive test has not automatically passed a constant-power test. It also explains why forcing every real load into CC can conceal a relevant voltage-dependent demand.<\/p>\n<h2 id=\"use-cv-as-a-sink-with-the-correct-source\"><span class=\"ez-toc-section\" id=\"Use_CV_as_a_sink_with_the_correct_source\"><\/span>Use CV as a sink, with the correct source<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>CV operation deserves a separate check. In the <a href=\"https:\/\/www.keysight.com\/us\/en\/assets\/9921-01404\/user-manuals\/EL34243-90000-User-Guide.pdf\" target=\"_blank\" rel=\"noopener\">Keysight EL30000 user guide<\/a>, CV mode controls terminal voltage by sinking current, subject to its limits. This is useful when the source under test is intended to regulate current. It is not a promise that the load can supply missing energy to hold a rail up.<\/p>\n<p>When a stiff voltage-regulated supply and a CV load demand incompatible terminal voltages, current can move toward a configured or physical limit. Decide which device is intended to regulate voltage and what limits define the test. For a battery or another device that must both deliver and absorb energy, confirm the required operating quadrants; a conventional sinking load alone does not provide a complete bidirectional simulator.<\/p>\n<h2 id=\"check-the-full-operating-envelope\"><span class=\"ez-toc-section\" id=\"Check_the_full_operating_envelope\"><\/span>Check the full operating envelope<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Use the selected instrument\u2019s voltage-current-power operating area, minimum operating voltage, channel configuration and cooling requirements. <a href=\"https:\/\/www.keysight.com\/gb\/en\/assets\/3121-1101\/application-notes\/The-Power-Handbook.pdf\" target=\"_blank\" rel=\"noopener\">Keysight\u2019s Power Handbook<\/a> explains electronic-load operating modes and the need to remain within the allowed voltage, current and power envelope. Maximum voltage, maximum current and maximum watts are not necessarily available together.<\/p>\n<p>For an independently calculated example, an instrument limited to 200 W cannot sustain 30 V at 10 A, because that point requires 300 W. Check any time-limited overload region separately rather than treating it as a continuous rating. At the other end, a load may lose current-control capability as voltage approaches zero; a high headline wattage does not resolve that boundary.<\/p>\n<p>For dynamic work, specify both load levels, slew rate or transition time, dwell times, repetition rate and the required measured waveform. A programmed fast step is not evidence that the same current transition occurred at the DUT terminals. Connection impedance, measurement arrangement and the instrument\u2019s response affect the achieved test.<\/p>\n<h2 id=\"keep-a-record-that-makes-the-result-reusable\"><span class=\"ez-toc-section\" id=\"Keep_a_record_that_makes_the_result_reusable\"><\/span>Keep a record that makes the result reusable<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Keep the supply model and revision, input conditions, load instrument and firmware, selected mode and range, setpoints, limits and timing together. Identify the voltage measurement point, record any instrument voltage-sense configuration used, and save the actual current and voltage traces needed for the decision. A front-panel current average alone cannot establish the shape of a short transient.<\/p>\n<p>State the acceptance rule before collecting results. It might concern steady output tolerance, a permitted transient excursion, or recovery within a time window. Use the rule relevant to the equipment; this article does not prescribe a universal ripple or transient limit.<\/p>\n<p>Approve the method when the selected mode represents the intended demand, the instrument remains within its documented envelope and the achieved waveform supports the acceptance decision. Hold the result if compliance, bandwidth or a protection limit changes the test. Change the method when the real load needs behavior the chosen mode cannot reproduce.<\/p>\n<p>Send WEHO the supply model, intended load behavior, operating conditions and acceptance limits to discuss the documentation and validation requirements for your application.<\/p>\n<p><a class=\"primary-cta\" href=\"https:\/\/www.wehopower.com\/ur\/contact\/\" data-link-role=\"inquiry\">Discuss your power supply load requirements<\/a><\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Match the load control law to the real device, then check voltage, current, power and dynamic limits before accepting a test result.<\/p>","protected":false},"author":2,"featured_media":20123,"parent":0,"menu_order":103,"comment_status":"closed","ping_status":"","template":"","format":"standard","meta":{"_acf_changed":false,"_joinchat":[],"footnotes":""},"news_category":[284],"class_list":["post-20165","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\/20165","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=20165"}],"version-history":[{"count":1,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news\/20165\/revisions"}],"predecessor-version":[{"id":20175,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news\/20165\/revisions\/20175"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/media\/20123"}],"wp:attachment":[{"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/media?parent=20165"}],"wp:term":[{"taxonomy":"news_category","embeddable":true,"href":"https:\/\/www.wehopower.com\/ur\/wp-json\/wp\/v2\/news_category?post=20165"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}