{"id":20542,"date":"2025-12-06T01:22:19","date_gmt":"2025-12-05T17:22:19","guid":{"rendered":"https:\/\/viox.com\/?p=20542"},"modified":"2025-12-06T01:22:21","modified_gmt":"2025-12-05T17:22:21","slug":"how-to-read-time-delay-relay-datasheets-specifications","status":"publish","type":"post","link":"https:\/\/test.viox.com\/fr\/how-to-read-time-delay-relay-datasheets-specifications\/","title":{"rendered":"Relais temporis\u00e9 Fiche technique: Comment Lire les Sp\u00e9cifications"},"content":{"rendered":"
\n

Un fabricant de panneaux de commande avait un jour command\u00e9 50 relais temporis\u00e9s sur la base d\u2019une seule sp\u00e9cification : \u201c Temporisation 10 secondes, 24 V \u201d. \u00c0 la r\u00e9ception, la moiti\u00e9 des relais ne se d\u00e9clenchaient pas de mani\u00e8re fiable car le signal de commande ne durait que 20 millisecondes \u2014 en de\u00e7\u00e0 de la largeur d\u2019impulsion minimale d\u2019entr\u00e9e de 50 ms, enfouie dans la fiche technique. Le projet fut bloqu\u00e9 deux semaines en attendant l\u2019exp\u00e9dition de relais de remplacement. Le fabricant savait quelle fonction de temporisation il lui fallait, mais avait n\u00e9glig\u00e9 une sp\u00e9cification critique d\u00e9terminant si le relais fonctionnerait r\u00e9ellement.<\/p>\n

Ce sc\u00e9nario se r\u00e9p\u00e8te dans tous les secteurs. Les ing\u00e9nieurs sp\u00e9cifient des relais, les responsables des achats comparent les devis, les techniciens de maintenance recherchent des \u00e9quivalents \u2014 tous s\u2019appuient sur les fiches techniques pour prendre la bonne d\u00e9cision. Mais les fiches techniques des relais temporis\u00e9s regroupent des dizaines de sp\u00e9cifications dans des tableaux denses, avec une terminologie qui varie souvent d\u2019un fabricant \u00e0 l\u2019autre. Si une sp\u00e9cification cl\u00e9 est oubli\u00e9e, cela entra\u00eene des d\u00e9faillances sur le terrain, une usure pr\u00e9matur\u00e9e des contacts, ou des relais qui fonctionnent en laboratoire mais l\u00e2chent face aux variations r\u00e9elles de temp\u00e9rature et de tension.<\/p>\n

Apprendre \u00e0 lire une fiche technique ne consiste pas \u00e0 m\u00e9moriser chaque sp\u00e9cification \u2014 mais \u00e0 savoir quelles sp\u00e9cifications comptent pour votre application et comment les interpr\u00e9ter correctement. La pr\u00e9cision de temporisation n\u2019a pas la m\u00eame signification sur toute l\u2019\u00e9chelle que sur les plages courtes. Les courants assign\u00e9s des contacts pour charges r\u00e9sistives ne s\u2019appliquent pas aux sol\u00e9no\u00efdes inductifs. La plage de tension de service n\u2019est pas la m\u00eame que la tension de lib\u00e9ration. Ces distinctions transforment la fiche technique d\u2019un document intimidant en un outil de d\u00e9cision qui \u00e9vite des erreurs co\u00fbteuses et garantit un fonctionnement fiable.<\/p>\n

Structure d\u2019une fiche technique : ce que vous y trouverez et o\u00f9<\/h2>\n

Les fiches techniques des relais temporis\u00e9s<\/a> suivent une structure pr\u00e9visible, bien que les fabricants agencent les sections diff\u00e9remment. Savoir o\u00f9 trouver rapidement l\u2019information fait gagner du temps et r\u00e9duit le risque de n\u00e9gliger des sp\u00e9cifications critiques.<\/p>\n

La plupart des fiches techniques commencent par une vue d\u2019ensemble du mod\u00e8le et les modes de fonctionnement,<\/strong> une section pr\u00e9sentant les fonctions de temporisation disponibles \u2014 temporisation \u00e0 la mise sous tension, temporisation \u00e0 la coupure, intervalle, multifonction. Cela vous indique quelles variantes de relais existent au sein d\u2019une famille de produits. Vient ensuite le r\u00e9glage de la plage de temporisation<\/strong>: les \u00e9chelles de temps disponibles (0,1 s, 1 s, 10 s, jusqu\u2019\u00e0 100 heures) et la mani\u00e8re d\u2019ajuster la temporisation \u2014 potentiom\u00e8tre rotatif, affichage num\u00e9rique ou param\u00e8tres programmables.<\/p>\n

Les caract\u00e9ristiques \u00e9lectriques<\/strong> occupent le c\u0153ur de la plupart des fiches techniques. Vous y trouverez des tableaux couvrant les sp\u00e9cifications de tension d\u2019alimentation (tension assign\u00e9e, plage admissible, fr\u00e9quence), les sp\u00e9cifications du circuit d\u2019entr\u00e9e (seuils de d\u00e9clenchement, largeur d\u2019impulsion minimale) et la consommation. Ces donn\u00e9es d\u00e9terminent si le relais s\u2019activera de mani\u00e8re fiable dans votre circuit de commande.<\/p>\n

Les sp\u00e9cifications de sortie<\/strong> d\u00e9taillent la configuration des contacts (SPDT, DPDT<\/a>), contact ratings by load type (resistive, inductive AC\/DC, lamp loads), and endurance (mechanical life, electrical life at rated load). This section tells you whether the relay can actually switch your load without premature failure.<\/p>\n

Performance characteristics<\/strong> quantify timing behavior: accuracy of operating time (usually as percent of full scale), setting error from the adjustment mechanism, influence of supply voltage variation, and influence of ambient temperature. You\u2019ll also find recovery time (minimum time between operations) and minimum control impulse duration here.<\/p>\n

Environmental ratings<\/strong> cover operating and storage temperature ranges, humidity limits, vibration\/shock resistance, and pollution degree per IEC 60664-1. These specs determine whether the relay survives your installation environment.<\/p>\n

Standards and approvals<\/strong> list certifications: IEC\/EN 61812-1 (the international time relay standard), UL 508\/cUL (North America), CE marking with referenced EMC directives. This section proves compliance and often includes insulation coordination data\u2014overvoltage category and impulse withstand voltage.<\/p>\n

Dimensions and wiring<\/strong> show physical size, mounting method (DIN-rail<\/a> width, plug-in socket pinout, panel cutout), terminal types, and connection diagrams. For replacement scenarios, this section determines drop-in compatibility.<\/p>\n

Understanding this structure lets you navigate any manufacturer\u2019s datasheet efficiently\u2014you know what information exists and where to find it.<\/p>\n

\"Annotated
Figure 1: Annotated time delay relay datasheet overview showing major specification sections. Color-coded callouts identify timing parameters (green), electrical ratings (blue), contact specifications (orange), environmental ratings (purple), dimensions (gray), and certifications (red). Understanding this structure helps you navigate any manufacturer\u2019s datasheet efficiently.<\/figcaption><\/figure>\n

Timing Specifications Explained<\/h2>\n

Timing specifications define how accurately and consistently the relay delivers its intended delay. These specs directly determine whether your application gets the timing precision it needs\u2014or experiences frustrating variability that causes process problems.<\/p>\n

Time Ranges and Setting Scales<\/h3>\n

Datasheets list available time ranges as base scales: 0.1 s, 1 s, 10 s, 100 s, up to 100 hours or more. Each scale covers a settable range, typically 1.2\u00d7 the base value. For example, a 10 s scale might cover 10\u2013120 seconds. This structure tells you two things: whether your target delay falls within the relay\u2019s capability, and how fine-grained the adjustment will be. A 0.1 s scale gives you precise sub-second control; a 100 s scale trades precision for long-duration capability.<\/p>\n

Accuracy of Operating Time<\/h3>\n

This is the deviation between the set timing value and the actual measured timing under reference conditions (usually 23\u00b0C, rated voltage). Accuracy is almost always expressed as percent of full scale (FS)<\/strong>, not percent of set value. This distinction matters enormously.<\/p>\n

Example: A relay with \u00b11% FS accuracy on a 12-second scale has a \u00b10.12 second error band\u2014whether you set 2 seconds or 12 seconds. At a 2-second setting, that \u00b10.12 s represents a \u00b16% error relative to your target. At 12 seconds, it\u2019s only \u00b11%. The shorter your timing setting relative to full scale, the larger the percentage error becomes. For very short ranges (sub-second), datasheets often add an absolute term: \u201c\u00b11% FS + 10 ms max.\u201d This accounts for circuit switching delays that don\u2019t scale with time range.<\/p>\n

When comparing relays, always check whether accuracy is specified at full scale or as a range-dependent value. Some manufacturers list different accuracy figures for different time scales.<\/p>\n

Setting Error vs Operating Time Accuracy<\/h3>\n

Setting error quantifies how precisely you can dial in your target time using the relay\u2019s adjustment mechanism\u2014potentiometer, rotary switch, or digital interface. A typical spec might read \u201c\u00b110% FS.\u201d This is separate from operating time accuracy, which measures how closely the relay hits the target you\u2019ve set. Total timing uncertainty is the combination of both: you might set the wrong target (setting error) and then miss that target by the operating time accuracy.<\/p>\n

For critical timing applications, minimize setting error by using digital\/programmable relays with numeric entry rather than analog potentiometer dials.<\/p>\n

R\u00e9p\u00e9tabilit\u00e9<\/h3>\n

Repeatability (sometimes called \u201crepeat accuracy\u201d) measures how consistently the relay produces the same timing value across multiple operations under identical conditions. High-quality relays show repeatability within \u00b10.5% FS; lower-cost units may drift to \u00b12% FS or more. In applications where cycle-to-cycle consistency matters\u2014sequential machine operations, synchronized motor starting\u2014repeatability becomes your critical spec.<\/p>\n

Some datasheets roll repeatability into the overall accuracy specification. Others list it separately. If you see only \u201caccuracy of operating time\u201d with no repeatability callout, assume repeatability is included within that accuracy band.<\/p>\n

Influence Quantities: Voltage and Temperature<\/h3>\n

Timing accuracy degrades under non-ideal conditions. Datasheets quantify this as \u201cinfluence of supply voltage\u201d and \u201cinfluence of ambient temperature,\u201d again expressed as percent of full scale.<\/p>\n

Typical voltage influence: \u00b10.5% FS over the allowable supply voltage range (e.g., 85%\u2013110% of rated voltage). If your supply voltage swings from 22 VDC to 26 VDC on a 24 VDC relay, expect up to \u00b10.5% FS additional timing error.<\/p>\n

Typical temperature influence: \u00b12% FS over the operating temperature range (e.g., \u221220\u00b0C to +60\u00b0C). Installing a relay in a hot control cabinet near heating equipment can push ambient temperature to 50\u00b0C or higher, adding significant timing drift.<\/p>\n

Critical tolerance stacking<\/strong>: Your worst-case timing error is the sum of operating time accuracy + voltage influence + temperature influence, all on a full-scale basis. For a 10 s scale relay with \u00b11% FS accuracy, \u00b10.5% FS voltage influence, and \u00b12% FS temperature influence, your worst-case band is \u00b13.5% FS = \u00b10.35 seconds. If you need tighter timing than that, choose a relay with better influence specifications or control your voltage and temperature environment more tightly.<\/p>\n

Recovery Time and Minimum Control Impulse<\/h3>\n

Recovery time<\/strong> (also called \u201cminimum power-OFF time\u201d or \u201creset time\u201d) specifies how long the relay must remain de-energized before it can reliably reset and start a new timing cycle. Typical values range from 0.05 s to 0.1 s. Cycling the relay faster than this can leave timing capacitors partially charged or internal logic in an undefined state, producing incorrect timing on the next cycle.<\/p>\n

Minimum control impulse<\/strong> (or \u201cminimum input signal width\u201d) defines the shortest pulse duration that reliably triggers timing on relays with separate start inputs. A spec of 50 ms means your control signal must stay high for at least 50 milliseconds. Shorter pulses may be ignored or produce erratic behavior. This is the spec that tripped up the control panel builder in our opening example\u201420 ms pulses couldn\u2019t trigger a relay requiring 50 ms minimum.<\/p>\n

Always verify your control circuit\u2019s pulse width and cycle timing against these specifications during design. Don\u2019t assume \u201cfast\u201d control signals will work without checking.<\/p>\n

\"Timing
Figure 2: Timing specifications breakdown showing three critical concepts. Setting Accuracy (\u00b110% FS) defines the tolerance band around your setpoint\u2014here a 5-second setting has \u00b10.5s tolerance when measured against the 10s full scale. Repeatability (\u00b10.5%) shows cycle-to-cycle consistency with measurements tightly clustered. Influence Quantities (temperature and voltage drift) add cumulative error\u2014in this example, \u00b11.5% temperature drift plus \u00b10.4% voltage drift yields \u00b12.4% total worst-case error under extreme conditions.<\/figcaption><\/figure>\n

Electrical Ratings: Voltage and Power Requirements<\/h2>\n

Electrical ratings define the relay\u2019s input circuit specifications\u2014what it needs to operate reliably. Get these wrong, and the relay won\u2019t energize consistently or may reset unexpectedly.<\/p>\n

Rated Supply Voltage and Operating Range<\/h3>\n

Tension nominale<\/strong> is the nominal design voltage: 24 VDC, 120 VAC, 240 VAC\/DC universal, etc. This is your reference point. But what matters operationally is the allowable supply voltage range<\/strong> ou operating voltage range<\/strong>\u2014typically 85% to 110% of rated voltage. A 24 VDC relay might specify 20.4\u201326.4 VDC operation. Stay within this window or the relay may malfunction.<\/p>\n

Some relays offer wider ranges. Universal-input models might accept 12\u2013240 VAC\/DC, automatically adapting to whatever supply you connect. Check whether your specific model variant supports the voltage range, or if you need to order a different part number for each voltage.<\/p>\n

Frequency rating<\/strong> matters for AC-powered relays: 50 Hz, 60 Hz, or 50\/60 Hz. Most modern relays handle both frequencies, but older electromechanical designs may be frequency-sensitive.<\/p>\n

Reset\/Release Voltage<\/h3>\n

This specification defines the voltage threshold below which the relay reliably de-energizes and resets its timing circuit. Typical values are 10%\u201320% of rated voltage. For a 24 VDC relay with a 15% release voltage, the relay resets when supply drops below 3.6 VDC.<\/p>\n

Why this matters: If your power supply experiences brownouts that dip to 50% of rated voltage but don\u2019t go below the release threshold, the relay may not fully reset. Subsequent timing cycles could behave erratically because internal capacitors or logic didn\u2019t fully discharge. Ensure your supply either stays above the minimum operating voltage or drops below the release voltage\u2014don\u2019t let it hover in the middle zone.<\/p>\n

Input Threshold Levels (for Voltage-Input Relays)<\/h3>\n

Relays with separate start\/trigger inputs specify high and low threshold voltages. A 24 VDC logic input might define \u201cHigh\u201d as \u226515 VDC and \u201cLow\u201d as \u22645 VDC, with a hysteresis band between 5\u201315 VDC. Your control signal must swing above the High threshold to guarantee recognition and below the Low threshold to reset.<\/p>\n

Don\u2019t assume a \u201c24 VDC input\u201d accepts 24 VDC logic levels. Some relays use 12 VDC thresholds even when powered by 24 VDC supply. Always check the input threshold specifications and verify your control circuit voltage compatibility.<\/p>\n

Consommation \u00e9lectrique<\/h3>\n

Datasheets list power consumption in watts or VA (for AC models). This figure accounts for the input circuit, timing electronics, and any indicator LEDs. Use maximum power consumption for power supply sizing, thermal calculations, and fuse\/breaker selection. In large control panels with dozens of relays, power consumption adds up quickly\u2014underestimating it leads to overloaded supplies and voltage sag under load.<\/p>\n

\"Technical
Figure 3: Voltage ratings explained on a visual scale. The diagram shows rated voltage (24 VDC nominal), operating voltage range (20.4\u201326.4 VDC in green), forbidden zones above and below operating limits (red), and release voltage threshold (~3.6 VDC). Your power supply must stay within the green operating range or drop below the release voltage\u2014avoid the middle zone where the relay may not fully reset.<\/figcaption><\/figure>\n

Contact and Output Specifications<\/h2>\n

Contact specifications determine whether the relay can safely switch your load. Misreading these specs causes premature contact wear, welding, and field failures.<\/p>\n

Configuration du contact<\/h3>\n

Time relays typically offer SPDT (single-pole double-throw, 1 C\/O contact) or DPDT (double-pole double-throw, 2 C\/O contacts). Each pole provides one normally-open (NO) and one normally-closed (NC) contact sharing a common terminal. DPDT relays let you switch two independent loads or create redundant control circuits.<\/p>\n

Some multifunction relays offer mixed configurations: one instantaneous contact (switches immediately when powered) and one timed contact (operates after the delay). Verify your model\u2019s contact arrangement matches your control logic requirements.<\/p>\n

Voltage and Current Ratings by Load Type<\/h3>\n

This is where most misapplication happens. Contact ratings are not universal<\/strong>\u2014they depend heavily on load type, and datasheets publish separate ratings for different loads.<\/p>\n

Resistive loads<\/strong> (heating elements, incandescent lamps, resistor banks) get the highest current ratings because they don\u2019t generate voltage spikes or arc energy during switching. A relay might be rated 5 A at 250 VAC resistive and 5 A at 30 VDC resistive.<\/p>\n

Inductive loads<\/strong> (solenoids, contactors, motor coils, transformers) generate back-EMF voltage spikes when switched, creating sustained arcing that erodes contacts. DC inductive loads are particularly harsh because DC arcs don\u2019t self-extinguish at zero-crossing like AC arcs do. The same relay rated 5 A resistive might be limited to 0.1 A at 125 VDC inductive with L\/R = 7 ms time constant. That\u2019s a 50\u00d7 derating. If you\u2019re switching a 24 VDC solenoid, you might get 3 A; at 125 VDC, only 0.1 A.<\/p>\n

AC utilization categories<\/strong> (per IEC standards) further refine ratings:<\/p>\n