Relay Model Numbering Guide: Schneider, Siemens, IDEC , Finder & OMRON
Selecting the right industrial relay can be frustrating when catalog numbers differ wildly between brands. A part number like RXM2AB2P7 or 3RH11 40‑1AP00 looks cryptic, and misreading the code can lead to mismatched coil voltages, contact forms or incompatible sockets. This guide breaks down the naming conventions used by Schneider, Siemens, IDEC (Izumi), Finder and OMRON. We focus on model number structure, standard terminal numbering, and how to cross‑reference sockets, while highlighting that CDGKZ manufactures OEM/ODM relay sockets compatible with these brands.
TL;DR
Standard contact forms: Understand SPST, SPDT and double‑throw arrangements and how they map to form A/B/C (NO/NC) relays. EN 50005 standardises terminal numbers such as 11 (common), 12 (NC) and 14 (NO).
Brand‑specific codes: OMRON’s G2R‑@‑S series uses digits for poles, terminal type and options (LED/diode/test button); Finder’s 40.52 code shows series, pin pitch, number of poles, coil type and options; IDEC’s RJ series uses letters for contact form and voltage codes.
Cross‑reference sockets: Always verify coil voltage and contact arrangement when choosing sockets; EN 50005 terminal numbers ensure interchangeability. CDGKZ supplies compatible sockets for Schneider, Siemens, IDEC, Finder and OMRON relays.
External standards: Relay naming conventions follow international standards such as EN 61810 (electromechanical relays) and EN 50005 (terminal numbering). Refer to authoritative documents (e.g., Finder technical information) for further details.
Understanding Relay Contact Forms & Terminal Numbering
Relays control circuits by opening and closing contacts when a coil is energised. The combination of poles and throws defines the contact form. Common configurations include single‑pole single‑throw (SPST), single‑pole double‑throw (SPDT), double‑pole single‑throw (DPST) and double‑pole double‑throw (DPDT). A single pole means one independent contact set; a double pole means two sets switching simultaneously. Throw indicates whether there is one (single throw) or two (double throw) possible contact positions. For example, an SPDT relay has three terminals—common, normally closed (NC) and normally open (NO). When the coil is not energised, the common terminal connects to NC; energising the coil transfers the common terminal to NO.
Standards help unify terminology. EN 50005 specifies terminal numbering for general purpose relays: terminals ending in .1 (e.g., 11, 21, 31…) are common, .2 (12, 22, 32…) denote NC contacts and .4 (14, 24, 34…) indicate NO contacts. Coil terminals are marked A1 and A2. The standard even assigns .5, .6 and .8 for delayed contacts used in timers. Wikipedia summarises that an EN 50005‑compliant SPDT relay uses terminals 11, 12 and 14 for the common, NC and NO contacts respectively and A1/A2 for the coil.
Understanding these designations simplifies cross‑brand comparison. For example, a Schneider RXM2 or Siemens 3RH2 relay will often feature terminals marked 11–12–14 for each pole. When selecting sockets, ensure that the socket follows EN 50005 so that numbering matches across brands. CDGKZ’s sockets follow this standard, ensuring compatibility.
Key Takeaways
SPST, SPDT, DPST and DPDT describe the number of poles (contact sets) and throws (positions)
EN 50005 assigns numbers to relay terminals—.1 for common, .2 for NC and .4 for NO; coil terminals are A1/A2.
Standardised numbering makes it easier to cross‑reference sockets and wiring diagrams, regardless of brandInternal link: Learn more about PCB‑level relay socket parameters on our product page.
Internal link: Learn more about PCB‑level relay socket parameters on our product page.
OMRON Relay Model Number Structure (G2R‑@‑S Series Example)
OMRON’s G2R‑@‑S (S) plug‑in relays use a structured model number that encodes key characteristics. The datasheet lists a Model Number Legend where each position corresponds to a design choice. The first digit indicates the number of poles: 1 for a single‑pole relay and 2 for a double‑pole relay. Next is the terminal style: S denotes plug‑in terminals suitable for sockets. The third group defines the classification or options—blank for general‑purpose, N for LED indicator, D for built‑in diode (DC coil), ND for both LED and diode, NI for LED with test button, and NDI for LED, diode and test button. Finally, the coil voltage is specified (e.g., 12 VDC, 24 VAC/24 VDC) and optional suffixes such as (S) indicate models with mechanical operation indicator and nameplate.
When ordering, OMRON recommends adding the rated coil voltage to the base model. For example, G2R‑1‑S 12 VDC (S) specifies a single‑pole plug‑in relay with indicator/test button and 12 V DC coil. The classification codes also help identify additional features such as LED indicators (e.g., G2R‑1‑SN) or diodes (G2R‑2‑SD). OMRON provides matching sockets (P2RF‑05‑PU, P2RFZ‑08‑E etc.) for these relays. Always check that the socket rating matches the coil voltage and current.
For other OMRON families like MY, G5 or LY, the pattern differs slightly but still conveys poles, coil voltage and options. For example, MY2N‑G‑AC220 is a two‑pole relay (MY2), with LED indicator (N), gold‑plated contacts (G) and 220 VAC coil; the suffix ‑S would indicate plug‑in terminals. Always refer to the manufacturer’s datasheet to decode these codes.
Key Takeaways
OMRON’s model number positions describe number of poles, terminal type, options (LED, diode, test button) and coil voltage.
Suffixes like N, D, ND or NDI indicate accessories such as LED indicators and surge‑suppression diodes.
When ordering, append the rated coil voltage and choose the correct socket; OMRON provides dedicated sockets (P2RF, P2RFZ etc.)
Internal link: See our selection of OMRON-compatible relay sockets here.
Finder Relay Numbering System (40 Series Example)
Finder uses a numeric code separated by dots to describe its relays, especially in the 40 Series. The ordering information in the 40 Series catalogue decodes the part number 40.52.8.230.0000 into distinct attributes:
Series and type – The first two digits (40) identify the series. The second group (5 or 6) denotes the pin pitch: 3 = 3.5 mm PCB mounting, 5 = 5 mm plug‑in or PCB mounting and 6 = 5 mm plug‑in mounting.
Number of poles – The digit after the dot indicates the number of change‑over contacts: 1 for single‑pole and 2 for double‑pole relays.
Coil version – The following digit identifies the coil technology: 6 for AC/DC bistable (latching), 7 for sensitive DC coils (0.5 W), 8 for AC coils and 9 for standard DC coils (0.65 W).
Coil voltage code – The next number(s) encode the coil voltage. For example 8 in 40.52.8.230.0000 corresponds to an AC coil (50/60 Hz); the subsequent digits 230 specify 230 V.
Contact material and circuit – The letter positions (A, B, C, D) describe contact material (AgNi, AgSnO₂, etc.) and contact circuit: 0 for change‑over (CO), 3 for normally‑open (NO) and 2 for normally‑closed (NC).
Special versions & options – Final digits indicate options such as wash‑tight sealing or high‑temperature versions (e.g., 1 = wash‑tight, 3 = high‑temperature) and pin length options (0 for 5.2 mm, 2 for 3.5 mm).
Thus, 40.52.8.230.0000 decodes to: 40 Series, plug‑in version (5 mm pin pitch), double‑pole (2 CO) relay with AC coil, 230 V coil voltage, standard contact material and change‑over contacts, standard version and 5.2 mm pin length. Finder emphasises that only specific combinations of options are allowed and provides a table showing preferred selections for availability. Always cross‑check coil voltage and contact rating when selecting sockets.
| Field | Finder (40 Series Example) | OMRON (G2R Series Example) | IDEC (RJ Series Example) |
|---|---|---|---|
| Series / Family | 40 = Series 40 miniature relays | G2R = General purpose plug-in relay family | RJ = RJ Slim relay family |
| Mounting / Pin Pitch | 5 = 5.0 mm plug-in/PCB, 6 = 5.0 mm plug-in, 3 = 3.5 mm PCB | -S = Plug-in terminals (for socket) | S = Blade (plug-in), V = PCB type |
| Number of Poles | 1 = SPDT, 2 = DPDT | 1 = 1-pole, 2 = 2-pole | 1 = 1-pole, 2 = 2-pole, 4 = 4-pole |
| Coil Technology | 6 = Latching, 7 = Sensitive DC, 8 = AC coil, 9 = Standard DC | Options like N = LED, D = Diode, NDI = LED + diode + test button | Voltage prefix: D = DC, A = AC |
| Coil Voltage Code | e.g., 230 = 230V AC, 024 = 24V DC | Explicitly appended: e.g., 12VDC, 24VAC | e.g., D24 = 24V DC, A120 = 120V AC |
| Contact Material & Circuit | Letter positions: 0 = CO, 3 = NO, 2 = NC; material coded (AgNi, AgSnO₂) | Not coded in G2R, specified in datasheet | Indicated by letter: C = Form C (SPDT), A = Form A (SPST-NO) |
| Options / Accessories | Final digits: wash-tight, high-temp, pin length | Suffix codes: N = LED, D = diode, NDI = LED+diode+test button | Option letter: L = LED indicator, blank = standard |
Key Takeaways
Finder’s part numbers use groups of digits separated by dots to represent series, pin pitch, poles, coil type, voltage, contact material/circuit and options.
The fourth group defines coil technology (standard DC, sensitive DC, AC or latching), while subsequent digits specify the voltage.
Specific digits at the end designate contact materials (AgNi vs. AgSnO₂) and special versions like wash‑tight or high‑temperature.
Internal link: For Finder relay replacement sockets, visit our Finder‑compatible products.
IDEC Relay Code Explanation – RJ Series
IDEC (also marketed as Izumi) uses alphanumeric codes for its relays. The RJ series datasheet provides an ordering key where each segment of the model number represents a specific parameter. For blade‑type (plug‑in) RJ relays:
Number of poles: 1 = single‑pole, 2 = double‑pole.
Contact configuration: C indicates Form C (SPDT), A indicates Form A (SPST‑NO).
Options: A blank position denotes a standard model; L signifies an LED indicator.
Coil voltage: Codes start with D for DC and A for AC; numbers following denote voltage (e.g., D12 = 12 V DC, A120 = 120 V AC).
For PCB models the pattern is similar but uses a V in the third position and includes a H suffix for high‑capacity versions. For example, RJ1S‑CL‑D24 decodes to: RJ series, single pole (1), blade type (S), Form C contact (C), LED indicator (L), and 24 V DC coil (D24). RJ2V‑A‑A120 would be a two‑pole PCB model (2V), Form A contact (A), and 120 V AC coil (A120). IDEC emphasises the use of matching sockets for each relay; the selection guide lists compatible sockets and accessories.
Other IDEC families such as RU, RH or RY follow similar patterns: the first two letters define the series, the number indicates poles, and additional letters describe options like indicator lights, test buttons or check buttons. Always consult the product datasheet for exact decoding.
Key Takeaways
IDEC’s RJ model numbers use sequential groups for poles, contact configuration, options (LED), and coil voltage.
Voltage codes begin with D (DC) or A (AC), followed by the numeric voltage (e.g., D24, A120).
IDEC offers blade (S) and PCB (V) versions; ensure you choose the matching socket from IDEC’s selection guid
Internal link: Explore our IDEC-compatible relay sockets on the product page.
Schneider & Siemens Relay Model Naming Conventions & Cross‑Reference
While Schneider and Siemens each have unique series, their part numbers follow similar principles. Schneider’s Harmony RXM and RXZ plug‑in relays use prefixes to indicate the series (e.g., RXM for miniature plug‑in relays and RXZ for sockets) followed by digits representing the number of poles and contact arrangement. A typical Schneider model such as RXM2AB2P7 breaks down into:
Number of poles & contact form – 2A indicates two change‑over (2 CO) contacts.
Terminal style – B denotes plug‑in terminals; F would denote Faston blade terminals.
Options – Additional letters may indicate LED indicator (L) or test button (G). Schneider’s FAQ describes common contact forms (Form A/B/C) and defines normally open (NO), normally closed (NC) and change‑over contacts.
Coil voltage code – The final digits/letters (e.g., P7) correspond to coil voltage (230 V AC for P7) and options like protection diodes or polarity markings.
Although Schneider seldom publishes a formal legend, the pattern aligns with EN 50005 numbering: the first digits convey contact arrangement and the suffix defines coil voltage. For example, RXM4AB2BD would be a four‑pole change‑over relay with LED indicator and diode, rated for DC coil voltage.
Siemens SIRIUS 3RH/3TH contactor relays follow similar logic. The prefix 3RH identifies an auxiliary contactor relay, while 3RT refers to a main contactor. In the 3TH series, Siemens notes that terminal designations and identification numbers conform to EN 50011—a standard related to contactor relays. The next digits indicate auxiliary contact arrangement (e.g., 40 for 4 NO contacts and 31 for 3 NO + 1 NC), and suffixes such as ‑1AP00 specify coil voltage (AC), terminal type (screw vs. spring cage) and options. For example, 3RH11 40‑1AP00 decodes to a 4 NO auxiliary contactor relay with AC coil and screw terminals, while 3RH11 31‑2BB40 would be 3 NO + 1 NC with DC coil and spring‑type terminals. Siemens’ documentation emphasises that these relays conform to IEC 60947 and EN 60947 and that coil operating ranges follow 0.8–1.1 × rated voltage.
When cross‑referencing Schneider and Siemens relays, focus on the number of poles, contact configuration (e.g., 4 NO, 3 NO+1 NC), coil voltage and options like LED indication or diodes. Always consult the datasheet to ensure compatibility.
Key Takeaways
Schneider’s Harmony RXM relays use prefixes for the series, digits for poles/contact form and suffixes for coil voltage and options; e.g., RXM2AB2P7 → 2 CO, plug‑in, 230 V AC.
Siemens SIRIUS 3RH/3TH relays follow EN 50011 for terminal designations; digits after the prefix indicate contact configuration (e.g., 40 for 4 NO) and suffixes encode coil voltage and terminal type.
Always verify coil voltage and contact arrangement when selecting relays or sockets; CDGKZ sockets support both Schneider and Siemens numbering schemes.
Internal link: Browse our Schneider & Siemens relay socket compatibility guide here.
| Brand | Example Models | Series / Description |
|---|---|---|
| Schneider | RXM2AB2P7 | Harmony RXM series, 2CO, 230V AC, with LED indicator |
| RXM4AB2BD | Harmony RXM, 4CO, DC coil, with LED + diode | |
| RSL1N024P | RSL Slim, 1CO, 24V DC coil, ultra-slim type | |
| RXZE1M2C | Matching socket (base), DIN-rail mount | |
| RUMC3AB1P7 | Harmony RUM universal relay, 3CO, 230V AC | |
| Siemens | 3RH2140-1AP00 | Sirius 3RH auxiliary relay, 4NO, AC 230V |
| 3RH2131-1BB40 | Sirius 3RH auxiliary relay, 3NO+1NC, DC 24V | |
| 3RT2025-1AP00 | Sirius contactor relay, 3-pole, AC 230V | |
| 3TX7114-5BB04 | Plug-in interface relay, DC 24V, 2CO | |
| 3UG4511-1AW30 | Sirius monitoring relay, current/voltage detection | |
| IDEC | RJ1S-CL-D24 | RJ Slim series, 1-pole, with LED, 24V DC |
| RJ2S-CL-D24 | RJ Slim, 2-pole, with LED, 24V DC | |
| RH2B-UAC120V | RH series, 2-pole, 120V AC coil | |
| RY2N-UL-DC24V | RY series, 2-pole, 24V DC, with LED | |
| RU4S-C-D24 | RU series, 4-pole, 24V DC coil | |
| Finder | 40.52.8.230.0000 | Series 40, 2CO, 230V AC coil |
| 40.31.9.012.0000 | Series 40, 1CO, 12V DC coil | |
| 55.34.8.230.0040 | Series 55, 4CO, 230V AC | |
| 62.23.8.230.0040 | Series 62, timer relay, 230V AC | |
| 39.31.7.024.0060 | Series 39, interface relay, 24V DC | |
| OMRON | G2R-1-SN 24VDC | G2R series, 1-pole, with LED, 24V DC |
| G2R-2-SNDI 24VDC | G2R series, 2-pole, with LED + diode + test button | |
| MY2N-GS AC220 | MY series, 2-pole, with LED, 220V AC | |
| LY2N-D2 DC24 | LY series, 2-pole, 24V DC, with LED | |
| G7L-2A-TUB AC200 | G7L series, power relay, 2-pole, 200V AC |
FAQ
Below are common questions about relay model numbers and cross‑brand compatibility.
Q1. How do I identify the coil voltage in a relay part number?
Most manufacturers encode the coil voltage at the end of the part number. For example, OMRON’s G2R‑1‑S 12 VDC uses “12 VDC” to denote the coil voltage. Finder codes like 40.52.8.230.0000 use the fourth group (“8.230”) where 8 indicates an AC coil and 230 specifies 230 V. Always verify the voltage in the datasheet to avoid mismatches.
Q2. What do the letters A, B, C or D mean in relay model numbers?
These letters often describe contact arrangement and options. In Schneider’s part numbers, A can denote a single‑pole contact form (Form A, normally open) and B may refer to plug‑in terminals, while C often stands for change‑over contacts. In Finder codes, the letter positions define contact material (AgNi, AgSnO₂) and circuit type (CO/NO/NC). Always cross‑reference the manufacturer’s legend.
Q3. Can I use a relay socket from one brand with a relay from another brand?
Yes—provided the socket matches the relay’s terminal numbering and footprint. EN 50005 standardises terminal numbers (e.g., 11–12–14 for common/NC/NO); thus, a CDGKZ socket compliant with this standard can accommodate relays from Schneider, Siemens, IDEC, Finder and OMRON. Always ensure the socket’s current and voltage ratings meet or exceed the relay’s specifications.
Conclusion & Call To Action
Understanding relay model numbers saves time, reduces errors and ensures your designs meet safety standards. This guide explained how EN 50005 dictates terminal numberingelektrische-automatisierung.com, how OMRON, Finder and IDEC encode poles, options and coil voltagesassets.omron.eucdn.findernet.comus.idec.com, and how Schneider and Siemens relays follow similar principlestme.eu. Always consult the relevant datasheets and standards when selecting or cross‑referencing relays.
CDGKZ designs and manufactures OEM/ODM relay sockets that are fully compatible with Schneider, Siemens, IDEC, Finder and OMRON relays. Our sockets follow EN 50005 numbering and support the full range of coil voltages and contact configurations. Whether you need a cost‑effective replacement or a custom solution, contact us for samples and a quote. Let us help you simplify your next relay project.
