{"id":13640,"date":"2026-11-02T14:44:09","date_gmt":"2026-11-02T13:44:09","guid":{"rendered":"https:\/\/guemisa.es\/?p=13640"},"modified":"2026-11-03T11:10:29","modified_gmt":"2026-11-03T10:10:29","slug":"lvdt-laboratory-tests","status":"publish","type":"post","link":"https:\/\/guemisa.es\/en\/lvdt-ensayos-laboratorio\/","title":{"rendered":"LVDT for laboratory testing: accuracy, stroke and conditioner"},"content":{"rendered":"<div class=\"gm-guia\"><p class=\"gm-g-kicker\">Technical guide \u00b7 GUEMISA<\/p><div class=\"gm-g-resp\"><span>Quick response<\/span><p>For laboratory testing, a passive LVDT with an external conditioner is the best option when resolution, sensor size, or temperature range are important, while an amplified LVDT (with the electronics inside the housing) is preferred when connecting the sensor directly to a standardized 4\u201320 mA or 0\u201310 V input is desirable. The stroke length is chosen based on the expected maximum displacement, and linearity is calculated over that stroke: the shorter the stroke, the lower the absolute error.<\/p>\n<p>An LVDT (linear variable differential transformer) measures displacements without electrical contact between the core and the coils, so there is no friction or wear in the measurement.<\/p><\/div><figure class=\"gm-anim\" data-anim=\"lvdt\"><figcaption class=\"gm-anim-pie\">The primary is excited by alternating current; moving the core changes the voltage of each secondary and the electronics give a linear output with zero in the center.<\/figcaption><\/figure><nav class=\"gm-g-indice\"><b>In this guide<\/b><ol><li><a href=\"#principio-de-funcionamiento\">Operating principle<\/a><\/li><li><a href=\"#lvdt-amplificado-frente-a-lvdt-pasivo-con-acondicionador\">Amplified LVDT vs. passive LVDT with conditioner<\/a><\/li><li><a href=\"#carrera-y-linealidad\">Career and linearity<\/a><\/li><li><a href=\"#retorno-por-muelle-o-nucleo-libre\">Spring return or free core<\/a><\/li><li><a href=\"#palpadores-y-puntas-de-medida\">Probes and measuring tips<\/a><\/li><li><a href=\"#comparativa-de-productos\">Product comparison<\/a><\/li><li><a href=\"#que-productos-de-guemisa-encajan\">Which GUEMISA products are a good fit?<\/a><\/li><li><a href=\"#preguntas-frecuentes\">Frequently Asked Questions<\/a><\/li><\/ol><\/nav><h2 id=\"principio-de-funcionamiento\">Operating principle<\/h2>\n<p>The sensor has a primary winding and two secondary windings connected in opposition. An oscillator excites the primary winding with alternating current; in Schreiber passive series, for example, the excitation frequency is 10 kHz. Inside the assembly, a ferromagnetic alloy (Ni-Fe) core attached to a stem moves.<\/p>\n<ul>\n<li>With the core in the center, the voltages of the two secondary windings cancel each other out and the output is zero;<\/li>\n<li>When the core is displaced, one tension increases and the other decreases; the difference is proportional to the displacement;<\/li>\n<li>The direction of movement is indicated by the phase of the signal with respect to the excitation.<\/li>\n<\/ul>\n<p>Since the signal is continuous in space, the resolution of the sensor itself is theoretically infinite; in practice it is limited by noise from the electronics and the acquisition.<\/p>\n\n<h2 id=\"lvdt-amplificado-frente-a-lvdt-pasivo-con-acondicionador\">Amplified LVDT vs. passive LVDT with conditioner<\/h2>\n<p>The difference lies not in the measurement principle, but in where the excitation and demodulation electronics are located.<\/p>\n<div class=\"gm-g-tabla\"><table>\n<thead>\n<tr><th>Aspect<\/th><th>amplified LVDT<\/th><th>Passive LVDT + conditioner<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td>Electronics<\/td><td>Integrated into the sensor<\/td><td>External module (DIN rail or OEM)<\/td><\/tr>\n<tr><td>Exit<\/td><td>Normalized: 4\u202620 mA, 0\u202620 mA, 0\u202610 V, \u00b110 V<\/td><td>Low amplitude AC signal at the sensor; the module outputs 0\/4\u202620 mA, 0\u202610 V or \u00b110 V<\/td><\/tr>\n<tr><td>Feeding<\/td><td>Continuous (for example 18\u202630 VDC or 24 VDC)<\/td><td>Only the conditioning module<\/td><\/tr>\n<tr><td>Wiring between sensor and system<\/td><td>Standardized signal, less sensitive to noise<\/td><td>Short, shielded cable to the module<\/td><\/tr>\n<tr><td>Sensor size<\/td><td>It depends on the model; there are amplified ones from \u00d8 10 mm (Schreiber SM27)<\/td><td>Very small, from \u00d8 10 mm in Schreiber SM21 and SM210<\/td><\/tr>\n<tr><td>Adjustment<\/td><td>According to the model (some series allow scaling the output)<\/td><td>Gain and zero in the module<\/td><\/tr>\n<tr><td>When it fits<\/td><td>Instrumentation and acquisition with standard analog inputs<\/td><td>Limited spaces, extreme temperatures, or multiple sensors with the same air conditioner<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<p>In tests with long cable lengths or electrical noise from motors and drives, amplified current output is usually more convenient. In small test specimens or climate chambers, the passive sensor can be placed inside and the conditioner outside.<\/p>\n\n<h2 id=\"carrera-y-linealidad\">Career and linearity<\/h2>\n<h3>How to choose a career<\/h3>\n<p>Choose the standard stroke immediately above the maximum expected displacement, including adjustment positions. An excessively large range reduces sensitivity and, consequently, the useful signal at small deformations; a range that is too small pushes the core to the extremes, where linearity is worse. The data sheets use electrical stroke (the portion over which linearity is guaranteed) and mechanical stroke (the total physical travel): in the FTI 10, for example, 10 mm and 12 mm.<\/p>\n<h3>How to read linearity<\/h3>\n<p>It is expressed as a percentage of full scale. A 20 mm LVDT with \u00b10.25% has an error of \u00b10.05 mm, or \u00b150 \u00b5m; the same percentage on a 5 mm sensor gives \u00b112.5 \u00b5m. Repeatability is usually much lower than linearity error: the FTI 10 reports a typical repeatability of less than 2 \u00b5m, and the Schreiber SM224 probe a maximum repeatability of 0.15 \u00b5m. For tests comparing measurements, repeatability is more important than absolute linearity.<\/p>\n<h3>Resolution<\/h3>\n<p>The sensor does not limit the resolution; the conditioner, the analog-to-digital converter, and noise do. Schreiber SM12 series conditioners claim a thermal drift of less than 0.005%\/\u00b0C and a cutoff frequency of 800 Hz, data that should be considered depending on the test speed.<\/p>\n\n<h2 id=\"retorno-por-muelle-o-nucleo-libre\">Spring return or free core<\/h2>\n<div class=\"gm-g-tabla\"><table>\n<thead>\n<tr><th>Configuration<\/th><th>How it works<\/th><th>When is it convenient<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td>Free core<\/td><td>The core is mechanically attached to the part and moves inside the body without touching the walls.<\/td><td>Dynamic tests or tests with very tight spaces, and where contact force on the sample is not allowed<\/td><\/tr>\n<tr><td>Probe with spring return<\/td><td>The stem is pressed against the workpiece with a defined force<\/td><td>Spot measurements of dimension, thickness or deformation, without attaching the stem to the part<\/td><\/tr>\n<tr><td>Pneumatic return (SM224, option .P)<\/td><td>The force is adjusted by the pressure: 0.4 bar is equivalent to 0.7 N and 1 bar to 2.5 N<\/td><td>When it is necessary to control and reduce the force of contact<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<p>The contact force affects the measurement if the workpiece is soft or thin. According to GUEMISA data, the Schreiber SM224 probe applies approximately 0.7 N at the center of its travel, the Novotechnik FTI 10 LVDT with return requires 4 N with IP50 and 10 N with IP67, and the Novotechnik F200 requires less than 2 N.<\/p>\n\n<h2 id=\"palpadores-y-puntas-de-medida\">Probes and measuring tips<\/h2>\n<p>The tip is the part that touches the sample and determines the result. The Schreiber SM22 and SM224 probes have an M2.5 thread at the tip; the F200 is supplied with a threaded probe with a carbide tip and lock nut, allowing it to be attached to the object by friction. If the tip is carbide, wear is reduced on abrasive surfaces. A bellows protects the shaft from dust and splashes (the SM224 is rated IP65 with the bellows). Note that the spring force and the weight of the shaft limit the speed at which the probe follows the surface without losing contact.<\/p>\n\n<h2 id=\"comparativa-de-productos\">Product comparison<\/h2>\n<div class=\"gm-g-tabla\"><table>\n<thead>\n<tr><th>Product<\/th><th>Guy<\/th><th>Career<\/th><th>Linearity<\/th><th>Exit<\/th><th>Protection<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td>Novotechnik F200<\/td><td>Amplified, stem<\/td><td>5, 10 or 20 mm (electrical)<\/td><td>\u00b10.1 to \u00b10.3%<\/td><td>\u00b110 VDC<\/td><td>IP67 with EEM connector<\/td><\/tr>\n<tr><td>Novotechnik FTI 10<\/td><td>Amplified, with return<\/td><td>10 mm (electrical)<\/td><td>\u00b10.1, \u00b10.2 or \u00b10.4%<\/td><td>4\u202620 mA or 0\u202620 mA<\/td><td>IP50 or IP67<\/td><\/tr>\n<tr><td>Schreiber SM21<\/td><td>Passive<\/td><td>5 to 20 mm<\/td><td>less than 0.5% (0.25% optional)<\/td><td>AC, with air conditioner<\/td><td>IP66 or IP68<\/td><\/tr>\n<tr><td>Schreiber SM26 \/ SM28<\/td><td>Passive<\/td><td>24 to 360 mm<\/td><td>less than 0.5% (0.25% optional)<\/td><td>AC, with air conditioner<\/td><td>IP66 with connector, up to IP68 with cable<\/td><\/tr>\n<tr><td>Schreiber SM224<\/td><td>Passive probe<\/td><td>2, 5, 10 or 20 mm<\/td><td>less than 0.5% (0.25% optional)<\/td><td>AC, with air conditioner<\/td><td>IP65 with bellows<\/td><\/tr>\n<tr><td>Schreiber SM30<\/td><td>Amplified<\/td><td>5, 10 or 15 mm<\/td><td>\u00b10.5% (\u00b10.25% optional)<\/td><td>4\u202620 mA, 0\u202620 mA, \u00b110 V, 0\u202610 V<\/td><td>IP66 with M12 connector, IP68 with cable<\/td><\/tr>\n<tr><td>Schreiber SM41 \/ SM43<\/td><td>Amplified and programmable<\/td><td>20 to 360 mm<\/td><td>0.2% (up to 0.1% with correction)<\/td><td>4\u202620 mA, 0\u202620 mA, 0\u202610 V, 0\u20265 V<\/td><td>IP67, IP68 with cable<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n\n<h2 id=\"que-productos-de-guemisa-encajan\">Which GUEMISA products are a good fit?<\/h2>\n<div class=\"gm-g-cards\"><a class=\"gm-g-card\" href=\"https:\/\/guemisa.es\/en\/products\/transductor-de-posicion-inductivo-f200\/\"><span class=\"gm-g-foto\"><img decoding=\"async\" src=\"https:\/\/guemisa.es\/wp-content\/uploads\/2026\/10\/novotechnik-transductor-posicion-inductivo-f200-300x225.webp\" alt=\"Novotechnik F200\" loading=\"lazy\"><\/span><b>Novotechnik F200<\/b><span class=\"gm-g-datos\">5, 10 and 20 mm electrical strokes, \u00b110 VDC output, \u00b10.1 to \u00b10.3% linearity and near infinite resolution.<\/span><em>View technical specifications \u2192<\/em><\/a><a class=\"gm-g-card\" href=\"https:\/\/guemisa.es\/en\/products\/fti-10-inductive-position-transducer\/\"><span class=\"gm-g-foto\"><img decoding=\"async\" src=\"https:\/\/guemisa.es\/wp-content\/uploads\/2026\/11\/novotechnik-fti-10-sensor-inductivo-desplazamiento-lineal.webp-768x595.webp\" alt=\"Novotechnik FTI 10\" loading=\"lazy\"><\/span><b>Novotechnik FTI 10<\/b><span class=\"gm-g-datos\">10 mm electrical stroke, 4\u202620 mA or 0\u202620 mA output, typical repeatability less than 2 \u00b5m and IP50 or IP67.<\/span><em>View technical specifications \u2192<\/em><\/a><a class=\"gm-g-card\" href=\"https:\/\/guemisa.es\/en\/products\/linear-lvdt-schreiber-sm26-sm28\/\"><span class=\"gm-g-foto\"><img decoding=\"async\" src=\"https:\/\/guemisa.es\/wp-content\/uploads\/2025\/01\/Sm26A-768x508.jpg\" alt=\"Schreiber SM26 and SM28\" loading=\"lazy\"><\/span><b>Schreiber SM26 and SM28<\/b><span class=\"gm-g-datos\">Passive LVDT from 24 to 360 mm, free core or spring-loaded probe; combines with the SM10 and SM12 series conditioners.<\/span><em>View technical specifications \u2192<\/em><\/a><a class=\"gm-g-card\" href=\"https:\/\/guemisa.es\/en\/products\/schreiber-sm224-lvdt-probe\/\"><span class=\"gm-g-foto\"><img decoding=\"async\" src=\"https:\/\/guemisa.es\/wp-content\/uploads\/2025\/01\/SM224-768x589.jpg\" alt=\"Schreiber SM224\" loading=\"lazy\"><\/span><b>Schreiber SM224<\/b><span class=\"gm-g-datos\">probe from 2 to 20 mm with maximum repeatability of 0.15 \u00b5m and pneumatic drive option.<\/span><em>View technical specifications \u2192<\/em><\/a><a class=\"gm-g-card\" href=\"https:\/\/guemisa.es\/en\/products\/amplified-lvdt-sensor-sm41-sm43\/\"><span class=\"gm-g-foto\"><img decoding=\"async\" src=\"https:\/\/guemisa.es\/wp-content\/uploads\/2026\/03\/sensor-lvdt-escalable-amplificado-schreiber-sm41-sm43-300x63.jpg\" alt=\"Schreiber SM41 and SM43\" loading=\"lazy\"><\/span><b>Schreiber SM41 and SM43<\/b><span class=\"gm-g-datos\">LVDT amplified from 20 to 360 mm, stainless steel housing \u00d8 25 mm, scalable output.<\/span><em>View technical specifications \u2192<\/em><\/a><a class=\"gm-g-card\" href=\"https:\/\/guemisa.es\/en\/products\/schreiber-sm12-lvdt-converter\/\"><span class=\"gm-g-foto\"><img decoding=\"async\" src=\"https:\/\/guemisa.es\/wp-content\/uploads\/2024\/12\/Amplificador-LVDT-300x170.jpg\" alt=\"Schreiber SM12\" loading=\"lazy\"><\/span><b>Schreiber SM12<\/b><span class=\"gm-g-datos\">DIN rail conditioner with 0\/4\u202620 mA, 0\u202610 V or \u00b110 V outputs for passive LVDTs.<\/span><em>View technical specifications \u2192<\/em><\/a><\/div><div class=\"gm-g-chips\"><a class=\"gm-g-chip\" href=\"https:\/\/guemisa.es\/en\/category\/lvdt\/\">Category: LVDT Sensors<\/a><\/div>\n\n<h2 id=\"documentacion-relacionada\">Documentation and related cases<\/h2><ul class=\"gm-g-rel\"><li><a href=\"https:\/\/guemisa.es\/en\/pdf-documents\/technical-explanation-of-what-an-lvdt-is\/\">LVDT: What it is and how it works (PDF)<\/a><\/li><li><a href=\"https:\/\/guemisa.es\/en\/pdf-documents\/catalog-lvdt-sensors-schreiber-messtechnik\/\">Schreiber Messtechnik LVDT Sensor Catalog (PDF)<\/a><\/li><li><a href=\"https:\/\/guemisa.es\/en\/technical-information\/\">All technical information about GUEMISA<\/a><\/li><\/ul><h2 id=\"preguntas-frecuentes\">Frequently Asked Questions<\/h2>\n<details class=\"gm-g-faq\"><summary>What is the difference between an amplified and a passive LVDT?<\/summary><p>The amplified sensor houses the excitation and demodulation electronics and delivers 4\u201320 mA or a standardized voltage. The passive sensor delivers an alternating signal and requires an external signal conditioner.<\/p>\n<\/details><details class=\"gm-g-faq\"><summary>How accurate is an LVDT?<\/summary><p>It depends on the model. In GUEMISA's data sheets, linearity ranges from \u00b10.1% in the F200 and FTI 10 to less than 0.5% in standard liabilities, and always refers to the full scale of the career.<\/p>\n<\/details><details class=\"gm-g-faq\"><summary>Can I use a passive LVDT with a PLC?<\/summary><p>Yes, but it needs a conditioner between the two that converts the alternating signal to 4\u202620 mA or 0\u202610 V, such as the Schreiber SM12 modules.<\/p>\n<\/details><details class=\"gm-g-faq\"><summary>When do I choose free core and when do I choose probe?<\/summary><p>The free core is used when the stem can be attached to the workpiece and contact force is not required. The spring-loaded probe is used for measuring without fixing the stem, in exchange for a contact force of between 0.7 N and 10 N depending on the model.<\/p>\n<\/details><details class=\"gm-g-faq\"><summary>Does an LVDT suffer wear and tear?<\/summary><p>The core does not touch the coils, so the measurement does not cause internal wear. In probes, wear is concentrated at the tip and in the stem guide.<\/p><\/details>\n\n<div class=\"gm-g-cta\"><b>Do you need help choosing?<\/b><p>Send us the application, race or reference you have and we will tell you the model and your order code.<\/p><p><a class=\"gm-g-btn\" href=\"mailto:ventas@guemisa.com?subject=Consulta%3A%20LVDT%20para%20ensayos%20de%20laboratorio%3A%20precisi%C3%B3n%2C%20carrera%20y%20acondicionador\">Write to ventas@guemisa.com<\/a> <a class=\"gm-g-btn gm-g-btn2\" href=\"tel:+34917642100\">91 764 21 00<\/a><\/p><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Amplified or passive LVDT with conditioner: principle, stroke, linearity, spring return or free core and probes for laboratory testing.<\/p>","protected":false},"author":1,"featured_media":13790,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[710],"tags":[],"class_list":["post-13640","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-guias-tecnicas"],"_links":{"self":[{"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/posts\/13640","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/comments?post=13640"}],"version-history":[{"count":5,"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/posts\/13640\/revisions"}],"predecessor-version":[{"id":13931,"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/posts\/13640\/revisions\/13931"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/media\/13790"}],"wp:attachment":[{"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/media?parent=13640"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/categories?post=13640"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/guemisa.es\/en\/wp-json\/wp\/v2\/tags?post=13640"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}