{"id":8234196,"date":"2026-10-24T17:30:32","date_gmt":"2026-10-24T17:30:32","guid":{"rendered":"https:\/\/scn.eu\/?post_type=scn_guide&#038;p=8234196"},"modified":"2026-10-24T17:30:32","modified_gmt":"2026-10-24T17:30:32","slug":"relay-vs-contactor-vs-ssr","status":"publish","type":"scn_guide","link":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/","title":{"rendered":"Relay vs contactor vs SSR \u2013 which should you choose?"},"content":{"rendered":"<div class=\"scn-guide\">\n<h1>Relay vs contactor vs SSR \u2013 which should you choose?<\/h1>\n<p class=\"g-lead\">A relay, a solid state relay (SSR) and a contactor all switch a load on and off with a small control signal. The right choice depends on current, voltage, how often you switch and whether the load runs on AC or DC.<\/p>\n<div class=\"g-short\"><b class=\"t\">Short answer<\/b><\/p>\n<ul>\n<li><b>Relay<\/b> \u2013 mechanical contacts for control signals and smaller loads, usually up to 10\u201316 A. Inexpensive, with a real air gap when off.<\/li>\n<li><b>Solid state relay (SSR)<\/b> \u2013 no moving parts, silent and wear-free. Runs warm and often needs a heatsink.<\/li>\n<li><b>Contactor<\/b> \u2013 a heavy-duty relay for motors, heating and power feeds, often three-phase and up to hundreds of amps.<\/li>\n<li><b>DC is harder than AC<\/b> \u2013 direct current has no zero crossing to put out the arc. Choose devices rated for DC.<\/li>\n<li><b>Rule of thumb<\/b> \u2013 frequent switching: SSR. Rare switching at high current: contactor.<\/li>\n<\/ul>\n<\/div>\n<h2>What is the difference between a relay, an SSR and a contactor?<\/h2>\n<p>A <b>relay<\/b> has a coil that pulls a moving contact. The control side and the load side are electrically isolated. On DIN rail, interface relays let a PLC output drive a valve or lamp.<\/p>\n<p>A <b>solid state relay (SSR)<\/b> has no moving parts. The control signal lights an LED in an optocoupler, and the light triggers a thyristor, triac or MOSFET that carries the load current. Switching is silent and wear-free. The price is heat and a small leakage current even when off.<\/p>\n<p>A <b>contactor<\/b> is essentially a relay built for high power. It usually has three main contacts for three-phase, arc chutes and room for auxiliary contacts. AC contactors are tested to IEC 60947-4-1 with utilisation categories, such as AC-1 for resistive loads and AC-3 for starting and stopping induction motors.<\/p>\n<figure><img loading=\"lazy\" src=\"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/scn-guide-rela-f1-en.webp\" alt=\"Principle sketch: a relay has a coil that pulls a moving contact, a solid state relay drives a thyristor through an optocoupler and a contactor has a coil that pulls three main contacts at once\" width=\"1520\" height=\"500\" loading=\"lazy\" decoding=\"async\"><figcaption>A relay and a contactor switch with mechanical contacts, an SSR with a semiconductor.<\/figcaption><\/figure>\n<div class=\"g-tbl\">\n<table>\n<thead>\n<tr>\n<th>Property<\/th>\n<th>Relay<\/th>\n<th>Solid state relay (SSR)<\/th>\n<th>Contactor<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td class=\"n\">Typical current<\/td>\n<td>Up to 10\u201316 A<\/td>\n<td>A few A to about 100 A per phase<\/td>\n<td>From about 10 A to over 1,000 A<\/td>\n<\/tr>\n<tr>\n<td class=\"n\">Wear<\/td>\n<td>Contacts wear<\/td>\n<td>No mechanical wear<\/td>\n<td>Contacts wear, but are more robust<\/td>\n<\/tr>\n<tr>\n<td class=\"n\">Frequent switching<\/td>\n<td>Less suitable<\/td>\n<td>Very suitable<\/td>\n<td>Less suitable<\/td>\n<\/tr>\n<tr>\n<td class=\"n\">Heat<\/td>\n<td>Low<\/td>\n<td>About 1\u20131.5 W per amp<\/td>\n<td>Low<\/td>\n<\/tr>\n<tr>\n<td class=\"n\">Typical failure<\/td>\n<td>Contacts weld together<\/td>\n<td>Semiconductor fails in the on state<\/td>\n<td>Contacts weld together<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>Heat, heatsinks and zero crossing \u2013 what you need to know about SSRs<\/h2>\n<p>A thyristor-based SSR has a voltage drop of roughly 1\u20131.5 V. As a rule of thumb that gives 1\u20131.5 W of heat per amp, so an SSR carrying 25 A gives off 25\u201340 W. A heatsink\u2019s capacity is given as thermal resistance in K\/W \u2013 the lower, the better. In a worked example from Celduc, one of their SSRs carrying 40 A at 30 \u00b0C ambient needs a 1.2 K\/W heatsink.<\/p>\n<p>An SSR with <b>zero-cross switching<\/b> turns on only when the AC voltage passes zero. That reduces electrical noise and suits resistive loads such as heating elements. An SSR with <b>random turn-on<\/b> switches immediately and suits inductive loads such as transformers, where switching at the zero crossing can cause high inrush currents.<\/p>\n<div class=\"g-short\">\n<p style=\"margin:0\">Example: a temperature controller pulses an SSR every second to keep a sealing jaw hot. That is over 80,000 operations a day \u2013 too many for a mechanical relay.<\/p>\n<\/div>\n<h2>AC or DC: why direct current is harder to break<\/h2>\n<p>When contacts open under load, an arc forms. With alternating current the current passes zero 100 times per second at 50 Hz, and the arc goes out at the next zero crossing. Direct current has no zero crossing. The arc can keep burning and destroy the contacts. That is why a relay rated 250 V AC often handles only 30 V DC at the same current.<\/p>\n<figure><img loading=\"lazy\" src=\"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/scn-guide-rela-f2-en.webp\" alt=\"Diagram: with alternating current the arc goes out when the current passes zero, with direct current the arc keeps burning until it is actively quenched\" width=\"1520\" height=\"540\" loading=\"lazy\" decoding=\"async\"><figcaption>With AC the arc goes out by itself at the zero crossing. With DC it must be actively quenched.<\/figcaption><\/figure>\n<p>Battery systems, electric vehicles and solar installations therefore use <b>high-voltage DC contactors<\/b> for 400\u20131,500 V. The contacts sit in a hermetically sealed, gas-filled ceramic chamber, and magnets blow out the arc. Some models break full current in one direction only. A battery that is both charged and discharged needs a bi-directional contactor. Solid-state DC contactors break without any arc.<\/p>\n<h2>Timing relays, monitoring relays and safety relays<\/h2>\n<ul>\n<li><b>Timing relay<\/b> \u2013 delays switch-on or switch-off, flashes or controls star-delta motor starting. Example: run-on time for a fan.<\/li>\n<li><b>Monitoring relay<\/b> \u2013 watches voltage, current, frequency, phase sequence or cos \u03c6 and trips when a value goes outside its limit. Example: a frequency monitor on a backup generator.<\/li>\n<li><b>Safety relay<\/b> \u2013 monitors emergency stops, guard doors and light curtains. It has force-guided contacts and two channels, and is chosen for the performance level (PL to EN ISO 13849-1) the risk assessment requires.<\/li>\n<\/ul>\n<h2>Which should you choose? Application examples<\/h2>\n<div class=\"g-tbl\">\n<table>\n<thead>\n<tr>\n<th>If you need to \u2026<\/th>\n<th>Choose<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Boost a PLC output to drive a valve or lamp<\/td>\n<td>Interface relay or I\/O relay on DIN rail<\/td>\n<\/tr>\n<tr>\n<td>Control heating with many operations per minute<\/td>\n<td>Zero-cross SSR with heatsink<\/td>\n<\/tr>\n<tr>\n<td>Start and stop a three-phase motor<\/td>\n<td>Contactor rated for AC-3 plus motor protection<\/td>\n<\/tr>\n<tr>\n<td>Connect and disconnect a 400\u20131,500 V DC battery<\/td>\n<td>High-voltage DC contactor<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<ul>\n<li><b>Factories<\/b> \u2013 interface relays for solenoid valves, SSRs for sealing jaws in packaging machines, contactors for conveyors.<\/li>\n<li><b>Vehicles and mobile machinery<\/b> \u2013 main contactors in electric forklifts, e-buses and mining machines.<\/li>\n<li><b>Energy<\/b> \u2013 battery storage and solar plants at 1,000\u20131,500 V DC, frequency monitors on generators.<\/li>\n<li><b>Infrastructure<\/b> \u2013 pumping stations with pump alternator relays and timing relays in ventilation.<\/li>\n<li><b>Aerospace and defence<\/b> \u2013 hermetically sealed relays for \u221270 to +125 \u00b0C.<\/li>\n<li><b>Laboratory and medical<\/b> \u2013 silent SSRs for heating in incubators and analysers.<\/li>\n<\/ul>\n<h2>Five common mistakes<\/h2>\n<ol class=\"g-pit\">\n<li><b>SSR without an adequate heatsink.<\/b> The rated current only applies with the right cooling. Use the temperature inside the cabinet.<\/li>\n<li><b>AC-rated relay on DC.<\/b> A 10 A 250 V AC rating says nothing about DC. Check the DC data in the datasheet.<\/li>\n<li><b>Wrong utilisation category.<\/b> A contactor handles more current for resistive loads (AC-1) than for motors (AC-3). Size it for the load.<\/li>\n<li><b>Forgetting the leakage current.<\/b> An SSR that is off leaks a few milliamps \u2013 enough to make an LED lamp glow or a PLC input read a one.<\/li>\n<li><b>No protection circuit.<\/b> Inductive loads cause voltage spikes when switched off, and lamps and capacitors cause high inrush currents. Use a flyback diode, RC snubber or varistor.<\/li>\n<\/ol>\n<h2>Relays and contactors from SCN<\/h2>\n<p>We carry interface relays from Mibbo and Tele Haase, solid state relays from Celduc, Mibbo and Nominal Controls, SSR heatsinks and accessories from Celduc and high-voltage DC contactors from Gigavac and Rincon Power. Timing and monitoring relays come from Tele Haase, and hermetically sealed relays for aerospace from Leach.<\/p>\n<h3>Examples from our range<\/h3>\n<div class=\"g-prod\"><a class=\"g-pc\" href=\"https:\/\/scn.eu\/en\/product\/sobr965560-th\/\"><img loading=\"lazy\" src=\"https:\/\/scn.eu\/wp-content\/uploads\/2025\/01\/SOBR965560-TH.jpeg\" alt=\"Celduc SOBR965560-TH Dual Power Solid State Relay 2x24A\" width=\"800\" height=\"800\" loading=\"lazy\" decoding=\"async\"><span class=\"g-pb\">Celduc<\/span><span class=\"g-pn\">SOBR965560-TH Dual Power Solid State Relay 2x24A<\/span><span class=\"g-pw\">New: two-phase zero-cross solid state relay with push-in terminals, 2 \u00d7 24 A at 24\u2013600 VAC \u2013 for heating loads.<\/span><\/a><a class=\"g-pc\" href=\"https:\/\/scn.eu\/en\/product\/gx16\/\"><img loading=\"lazy\" src=\"https:\/\/scn.eu\/wp-content\/uploads\/2025\/01\/gx16.jpeg\" alt=\"Gigavac GX16 chassis mount Contactor\" width=\"800\" height=\"800\" loading=\"lazy\" decoding=\"async\"><span class=\"g-pb\">Gigavac<\/span><span class=\"g-pn\">GX16 chassis mount Contactor<\/span><span class=\"g-pw\">Hermetically sealed chassis-mount contactor, IP67 and IP69K, for \u221255 to 85 \u00b0C.<\/span><\/a><a class=\"g-pc\" href=\"https:\/\/scn.eu\/en\/product\/e1k-e3k-coupling-relays\/\"><img loading=\"lazy\" src=\"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/tele-haase-coup-main.webp\" alt=\"Tele Haase E1K \/ E3K coupling relays\" width=\"800\" height=\"800\" loading=\"lazy\" decoding=\"async\"><span class=\"g-pb\">Tele Haase<\/span><span class=\"g-pn\">E1K \/ E3K coupling relays<\/span><span class=\"g-pw\">DIN rail coupling relays, 8 A at 250 V, that isolate PLC outputs from the load.<\/span><\/a><\/div>\n<div class=\"g-links\"><a href=\"https:\/\/scn.eu\/en\/product-category\/products\/components\/relays-and-sockets\/\">Relays and sockets<\/a><a href=\"https:\/\/scn.eu\/en\/product-category\/products\/components\/solid-state-relays-ssr\/\">Solid state relays (SSR)<\/a><a href=\"https:\/\/scn.eu\/en\/product-category\/products\/components\/power-contactors\/\">Power contactors<\/a><a href=\"https:\/\/scn.eu\/en\/product-category\/products\/components\/timing-relays\/\">Timing relays<\/a><a href=\"https:\/\/scn.eu\/en\/product-category\/products\/components\/monitoring-relays\/\">Monitoring relays<\/a><\/div>\n<div class=\"g-cta\">\n<p>Not sure whether your load needs a relay, an SSR or a contactor? Ask one of our engineers \u2013 you get an answer within 24 hours.<\/p>\n<p><a href=\"https:\/\/scn.eu\/en\/contact\/\">Ask an engineer<\/a><\/div>\n<h2>Frequently asked questions<\/h2>\n<details>\n<summary>What is the difference between a relay and a contactor?<\/summary>\n<p>Both use a coil to pull mechanical contacts. A contactor is built for higher currents and often has three main contacts for three-phase. Relays are mainly used for control signals and smaller loads.<\/p>\n<\/details>\n<details>\n<summary>Can a solid state relay replace a contactor?<\/summary>\n<p>Often, if the load is switched frequently and you can remove the heat. For motors and where you want an air gap in the off state, a contactor is usually better.<\/p>\n<\/details>\n<details>\n<summary>Why does my solid state relay get hot?<\/summary>\n<p>Its voltage drop of roughly 1\u20131.5 V gives 1\u20131.5 W of heat per amp. Without a heatsink it overheats at a few amps.<\/p>\n<\/details>\n<details>\n<summary>Can I use an AC relay for DC?<\/summary>\n<p>Only within the DC ratings in the datasheet, which are often much lower, since a DC arc is harder to put out.<\/p>\n<\/details>\n<details>\n<summary>What is an interface relay?<\/summary>\n<p>A relay between the control system and the load. It isolates the PLC output and lets a weak output switch a higher current or a different voltage.<\/p>\n<\/details>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>A relay, a solid state relay (SSR) and a contactor all switch a load on and off with a small control signal. The right choice depends on current, voltage, how often you switch and whether the load runs on AC or DC.<\/p>\n","protected":false},"author":11,"featured_media":8234073,"template":"","meta":{"_yoast_wpseo_focuskw":"relay vs contactor vs ssr","_yoast_wpseo_metadesc":"Relay vs contactor vs SSR: differences in current, lifetime, heat and AC\/DC switching, plus how to choose the right device for your load.","_kad_post_transparent":"","_kad_post_title":"hide","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"hide","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","_scn_guide_cats":[656,728,664,705,727],"_scn_guide_sectors":[1011,1037,1012],"_scn_guide_type":"tech","_scn_guide_order":36,"footnotes":""},"class_list":["post-8234196","scn_guide","type-scn_guide","status-publish","has-post-thumbnail","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Relay vs contactor vs SSR \u2013 which should you choose? | SCN<\/title>\n<meta name=\"description\" content=\"Relay vs contactor vs SSR: differences in current, lifetime, heat and AC\/DC switching, plus how to choose the right device for your load.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Relay vs contactor vs SSR \u2013 which should you choose? | SCN\" \/>\n<meta property=\"og:description\" content=\"Relay vs contactor vs SSR: differences in current, lifetime, heat and AC\/DC switching, plus how to choose the right device for your load.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/\" \/>\n<meta property=\"og:site_name\" content=\"SCN\" \/>\n<meta property=\"og:image\" content=\"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/scn-guide-rela-f1-en.webp\" \/>\n\t<meta property=\"og:image:width\" content=\"1520\" \/>\n\t<meta property=\"og:image:height\" content=\"500\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/webp\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"7 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/\",\"url\":\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/\",\"name\":\"Relay vs contactor vs SSR \u2013 which should you choose? | SCN\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/scn.eu\\\/wp-content\\\/uploads\\\/2026\\\/10\\\/scn-guide-rela-f1-en.webp\",\"datePublished\":\"2026-10-24T17:30:32+00:00\",\"description\":\"Relay vs contactor vs SSR: differences in current, lifetime, heat and AC\\\/DC switching, plus how to choose the right device for your load.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/#primaryimage\",\"url\":\"https:\\\/\\\/scn.eu\\\/wp-content\\\/uploads\\\/2026\\\/10\\\/scn-guide-rela-f1-en.webp\",\"contentUrl\":\"https:\\\/\\\/scn.eu\\\/wp-content\\\/uploads\\\/2026\\\/10\\\/scn-guide-rela-f1-en.webp\",\"width\":1520,\"height\":500,\"caption\":\"Principle sketch: a relay has a coil that pulls a moving contact, a solid state relay drives a thyristor through an optocoupler and a contactor has a coil that pulls three main contacts at once\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/guides\\\/relay-vs-contactor-vs-ssr\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/scn.eu\\\/en\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Relay vs contactor vs SSR \u2013 which should you choose?\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/#website\",\"url\":\"https:\\\/\\\/scn.eu\\\/en\\\/\",\"name\":\"SCN\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/scn.eu\\\/en\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/#organization\",\"name\":\"Sensor Control Nordic\",\"alternateName\":\"SCN\",\"url\":\"https:\\\/\\\/scn.eu\\\/en\\\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/#\\\/schema\\\/logo\\\/image\\\/\",\"url\":\"https:\\\/\\\/scn.eu\\\/wp-content\\\/uploads\\\/2026\\\/04\\\/SCN-logo-scaled.png\",\"contentUrl\":\"https:\\\/\\\/scn.eu\\\/wp-content\\\/uploads\\\/2026\\\/04\\\/SCN-logo-scaled.png\",\"width\":2560,\"height\":632,\"caption\":\"Sensor Control Nordic\"},\"image\":{\"@id\":\"https:\\\/\\\/scn.eu\\\/en\\\/#\\\/schema\\\/logo\\\/image\\\/\"},\"sameAs\":[\"https:\\\/\\\/www.linkedin.com\\\/company\\\/sensor-control-nordic-ab\"],\"location\":[{\"@type\":\"Place\",\"name\":\"SCN Walsall\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"46 Hall Lane, Walsall Wood\",\"addressLocality\":\"Walsall\",\"postalCode\":\"WS9 9DP\",\"addressCountry\":\"GB\",\"addressRegion\":\"West Midlands\"},\"telephone\":\"+44 1634 300 900\"},{\"@type\":\"Place\",\"name\":\"SCN Stockholm\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"Gustav III:s Boulevard 32\",\"addressLocality\":\"Solna\",\"postalCode\":\"169 73\",\"addressCountry\":\"SE\"},\"telephone\":\"+46 8 668 21 00\"},{\"@type\":\"Place\",\"name\":\"SCN Malm\u00f6\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"R\u00f6nnviksgatan 13\",\"addressLocality\":\"Malm\u00f6\",\"postalCode\":\"213 74\",\"addressCountry\":\"SE\"},\"telephone\":\"+46 40 688 02 00\"},{\"@type\":\"Place\",\"name\":\"SCN Sundsvall\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"Trafikgatan 11\",\"addressLocality\":\"Sundsvall\",\"postalCode\":\"856 44\",\"addressCountry\":\"SE\"},\"telephone\":\"+46 60 740 75 81\"},{\"@type\":\"Place\",\"name\":\"SCN Helsinki\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"Huopalahdentie 24A\",\"addressLocality\":\"Helsinki\",\"postalCode\":\"00350\",\"addressCountry\":\"FI\"},\"telephone\":\"+358 20 734 8600\"},{\"@type\":\"Place\",\"name\":\"SCN Tallinn\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"Narva mnt 5\",\"addressLocality\":\"Tallinn\",\"postalCode\":\"10117\",\"addressCountry\":\"EE\"},\"telephone\":\"+372 651 4550\"},{\"@type\":\"Place\",\"name\":\"SCN Oslo\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"Kristoffer Robins vei 13\",\"addressLocality\":\"Oslo\",\"postalCode\":\"0978\",\"addressCountry\":\"NO\"},\"telephone\":\"+47 23 88 89 62\"},{\"@type\":\"Place\",\"name\":\"SCN R\u00f8dekro\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"H\u00e6rvejen 8\",\"addressLocality\":\"R\u00f8dekro\",\"postalCode\":\"6230\",\"addressCountry\":\"DK\"},\"telephone\":\"+45 78 74 65 00\"},{\"@type\":\"Place\",\"name\":\"SCN Madrid\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"Paseo de la Castellana, 200\",\"addressLocality\":\"Madrid\",\"postalCode\":\"28046\",\"addressCountry\":\"ES\",\"addressRegion\":\"Comunidad de Madrid\"},\"telephone\":\"+34 93 641 59 97\"},{\"@type\":\"Place\",\"name\":\"SCN Tarnowskie G\u00f3ry\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"ul. Ma\u0142a 1B\",\"addressLocality\":\"Tarnowskie G\u00f3ry\",\"postalCode\":\"42-605\",\"addressCountry\":\"PL\"},\"telephone\":\"+48 511 199 460\"}],\"email\":\"sales@scn.eu\",\"areaServed\":[\"SE\",\"NO\",\"DK\",\"FI\",\"EE\",\"GB\",\"PL\",\"ES\"],\"knowsLanguage\":[\"en\",\"sv\",\"da\",\"fi\",\"nb\",\"et\",\"pl\",\"es\"]}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Relay vs contactor vs SSR \u2013 which should you choose? | SCN","description":"Relay vs contactor vs SSR: differences in current, lifetime, heat and AC\/DC switching, plus how to choose the right device for your load.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/","og_locale":"en_US","og_type":"article","og_title":"Relay vs contactor vs SSR \u2013 which should you choose? | SCN","og_description":"Relay vs contactor vs SSR: differences in current, lifetime, heat and AC\/DC switching, plus how to choose the right device for your load.","og_url":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/","og_site_name":"SCN","og_image":[{"width":1520,"height":500,"url":"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/scn-guide-rela-f1-en.webp","type":"image\/webp"}],"twitter_card":"summary_large_image","twitter_misc":{"Est. reading time":"7 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/","url":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/","name":"Relay vs contactor vs SSR \u2013 which should you choose? | SCN","isPartOf":{"@id":"https:\/\/scn.eu\/en\/#website"},"primaryImageOfPage":{"@id":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/#primaryimage"},"image":{"@id":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/#primaryimage"},"thumbnailUrl":"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/scn-guide-rela-f1-en.webp","datePublished":"2026-10-24T17:30:32+00:00","description":"Relay vs contactor vs SSR: differences in current, lifetime, heat and AC\/DC switching, plus how to choose the right device for your load.","breadcrumb":{"@id":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/#primaryimage","url":"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/scn-guide-rela-f1-en.webp","contentUrl":"https:\/\/scn.eu\/wp-content\/uploads\/2026\/10\/scn-guide-rela-f1-en.webp","width":1520,"height":500,"caption":"Principle sketch: a relay has a coil that pulls a moving contact, a solid state relay drives a thyristor through an optocoupler and a contactor has a coil that pulls three main contacts at once"},{"@type":"BreadcrumbList","@id":"https:\/\/scn.eu\/en\/guides\/relay-vs-contactor-vs-ssr\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/scn.eu\/en\/"},{"@type":"ListItem","position":2,"name":"Relay vs contactor vs SSR \u2013 which should you choose?"}]},{"@type":"WebSite","@id":"https:\/\/scn.eu\/en\/#website","url":"https:\/\/scn.eu\/en\/","name":"SCN","description":"","publisher":{"@id":"https:\/\/scn.eu\/en\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/scn.eu\/en\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/scn.eu\/en\/#organization","name":"Sensor Control Nordic","alternateName":"SCN","url":"https:\/\/scn.eu\/en\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/scn.eu\/en\/#\/schema\/logo\/image\/","url":"https:\/\/scn.eu\/wp-content\/uploads\/2026\/04\/SCN-logo-scaled.png","contentUrl":"https:\/\/scn.eu\/wp-content\/uploads\/2026\/04\/SCN-logo-scaled.png","width":2560,"height":632,"caption":"Sensor Control Nordic"},"image":{"@id":"https:\/\/scn.eu\/en\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.linkedin.com\/company\/sensor-control-nordic-ab"],"location":[{"@type":"Place","name":"SCN Walsall","address":{"@type":"PostalAddress","streetAddress":"46 Hall Lane, Walsall Wood","addressLocality":"Walsall","postalCode":"WS9 9DP","addressCountry":"GB","addressRegion":"West Midlands"},"telephone":"+44 1634 300 900"},{"@type":"Place","name":"SCN Stockholm","address":{"@type":"PostalAddress","streetAddress":"Gustav III:s Boulevard 32","addressLocality":"Solna","postalCode":"169 73","addressCountry":"SE"},"telephone":"+46 8 668 21 00"},{"@type":"Place","name":"SCN Malm\u00f6","address":{"@type":"PostalAddress","streetAddress":"R\u00f6nnviksgatan 13","addressLocality":"Malm\u00f6","postalCode":"213 74","addressCountry":"SE"},"telephone":"+46 40 688 02 00"},{"@type":"Place","name":"SCN Sundsvall","address":{"@type":"PostalAddress","streetAddress":"Trafikgatan 11","addressLocality":"Sundsvall","postalCode":"856 44","addressCountry":"SE"},"telephone":"+46 60 740 75 81"},{"@type":"Place","name":"SCN Helsinki","address":{"@type":"PostalAddress","streetAddress":"Huopalahdentie 24A","addressLocality":"Helsinki","postalCode":"00350","addressCountry":"FI"},"telephone":"+358 20 734 8600"},{"@type":"Place","name":"SCN Tallinn","address":{"@type":"PostalAddress","streetAddress":"Narva mnt 5","addressLocality":"Tallinn","postalCode":"10117","addressCountry":"EE"},"telephone":"+372 651 4550"},{"@type":"Place","name":"SCN Oslo","address":{"@type":"PostalAddress","streetAddress":"Kristoffer Robins vei 13","addressLocality":"Oslo","postalCode":"0978","addressCountry":"NO"},"telephone":"+47 23 88 89 62"},{"@type":"Place","name":"SCN R\u00f8dekro","address":{"@type":"PostalAddress","streetAddress":"H\u00e6rvejen 8","addressLocality":"R\u00f8dekro","postalCode":"6230","addressCountry":"DK"},"telephone":"+45 78 74 65 00"},{"@type":"Place","name":"SCN Madrid","address":{"@type":"PostalAddress","streetAddress":"Paseo de la Castellana, 200","addressLocality":"Madrid","postalCode":"28046","addressCountry":"ES","addressRegion":"Comunidad de Madrid"},"telephone":"+34 93 641 59 97"},{"@type":"Place","name":"SCN Tarnowskie G\u00f3ry","address":{"@type":"PostalAddress","streetAddress":"ul. Ma\u0142a 1B","addressLocality":"Tarnowskie G\u00f3ry","postalCode":"42-605","addressCountry":"PL"},"telephone":"+48 511 199 460"}],"email":"sales@scn.eu","areaServed":["SE","NO","DK","FI","EE","GB","PL","ES"],"knowsLanguage":["en","sv","da","fi","nb","et","pl","es"]}]}},"_links":{"self":[{"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/scn_guide\/8234196","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/scn_guide"}],"about":[{"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/types\/scn_guide"}],"author":[{"embeddable":true,"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/users\/11"}],"version-history":[{"count":2,"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/scn_guide\/8234196\/revisions"}],"predecessor-version":[{"id":8234249,"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/scn_guide\/8234196\/revisions\/8234249"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/media\/8234073"}],"wp:attachment":[{"href":"https:\/\/scn.eu\/en\/wp-json\/wp\/v2\/media?parent=8234196"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}