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Brand: Schneider Electric
Schneider Electric SR2B121BD Zelio SR2 Compact Smart Relay 12
Description
SR2B121BD compact Zelio smart relay with display and clock
The SR2B121BD is a Schneider Electric product listed in the datasheet as: compact smart relay, Zelio Logic SR2 SR3, 12 IO, 24V DC, clock, display, 4 relay outputs. The SR2B121BD is a compact Zelio Logic smart relay: a programmable relay that replaces timers and logic in simple automation tasks. It has 8 inputs, 4 relay outputs, a display with buttons and a real-time clock, powered from 24 V DC. Seven Star LLC supplies the SR2B121BD in Oman and the GCC as an independent supplier based in Muscat.
Reading the reference: SR2 is the compact Zelio smart relay, B marks the version with display and clock, 12 the I/O count, 1 the relay output type and BD the 24 V DC supply as in the datasheet title.
Technical specifications of the SR2B121BD
| Parameter | Specification |
|---|---|
| Manufacturer / part number | Schneider Electric / SR2B121BD |
| Description | compact smart relay, Zelio Logic SR2 SR3, 12 IO, 24V DC, clock, display, 4 relay outputs |
| Range of Product | Zelio Logic |
| Product or Component Type | Compact smart relay |
| Local display | With |
| Number or control scheme lines | 0 to 240 ladder; 0 to 500 FBD |
| Cycle time | 6 to 90 ms |
| Backup time | 10 years 25 °C |
| Clock drift | 12 min/year 0 to 55 °C; 6 s/month 25 °C |
| Checks | Program memory on each power up |
| [Us] rated supply voltage | 24 V DC |
| Supply voltage limits | 19.2 to 30 V |
| Maximum supply current | 100 mA without extension |
| Power dissipation in W | 3 W without extension |
| Reverse polarity protection | With |
| Discrete input number | 8 IEC 61131-2 Type 1 |
| Discrete input type | Resistive |
| Discrete input voltage | 24 V DC |
| Discrete input current | 4 mA |
| Counting frequency | 1 kHz discrete input |
| Voltage state 1 guaranteed | >= 15 V I1–IA and IH–IR discrete input circuit; >= 15 V IB–IG used as discrete input circuit |
| Voltage state 0 guaranteed | <= 5 V I1–IA and IH–IR discrete input circuit; <= 5 V IB–IG used as discrete input circuit |
| Current state 1 guaranteed | >= 1.2 mA IB–IG used as discrete input circuit; >= 2.2 mA I1–IA and IH–IR discrete input circuit |
| Current state 0 guaranteed | <= 0.5 mA IB–IG used as discrete input circuit; <= 0.75 mA I1–IA and IH–IR discrete input circuit |
| Input compatibility | 3-wire proximity sensors PNP discrete input |
| Analogue input number | 4 |
| Analogue Input Type | Common mode |
| Analogue input range | 0 to 10 V; 0 to 24 V |
| Temperature probe type | NTC 10k 25 °C; NTC 1000k 25 °C; KTY81 210/220/221/222/250; Pt 500 |
| Maximum permissible voltage | 30 V analogue input circuit |
| Analogue input resolution | 8 bits |
| LSB value | 39 mV analogue input circuit |
| Conversion time | Smart relay cycle time analogue input circuit |
| Conversion error | ± 5 % 25 °C analogue input circuit; ± 6.2 % 55 °C analogue input circuit |
| Repeat accuracy | ± 2 % 55 °C analogue input circuit |
| Operating distance | 10 m between stations, with screened cable (sensor not isolated) analogue input circuit |
| Input impedance | 12 kOhm IB–IG used as analogue input circuit; 12 kOhm IB–IG used as discrete input circuit |
| Number of Outputs | 4 relay |
| Output voltage limits | 24 to 250 V AC relay output; 5 to 30 V DC relay output |
| Contacts type and composition | NO relay output |
| Output thermal current | 8 A for all 4 outputs relay output |
| Electrical durability | AC-12 500000 cycles 230 V, 1.5 A relay output IEC 60947-5-1; AC-15 500000 cycles 230 V, 0.9 A relay output IEC 60947-5-1 |
Inputs, outputs and programming
Discrete inputs: 8 IEC 61131-2 Type 1. Analogue inputs: 4. Outputs: 4 relay. Program size: 0 to 240 ladder; 0 to 500 FBD. Cycle time: 6 to 90 ms. Clock: 12 min/year 0 to 55 °C; 6 s/month 25 °C. Backup time: 10 years 25 °C. Output current: 8 A for all 4 outputs relay output.
The device can be programmed from its front keys or from software on a PC, in ladder or function-block diagrams. The clock enables time-of-day functions such as lighting schedules and pump rotation.
Where a smart relay is right and where a PLC is better
A smart relay suits 8 to 40 I/O jobs with no network need. For Ethernet, large data or complex math, the M221 family is better. Compare with the modular SR3 relay, which accepts extension modules and a communication interface.
Analogue inputs let the SR2 read 0 to 10 V sensors, but with 8-bit resolution, so it is for coarse level and temperature tasks.
Selection checklist for the SR2B121BD
- I/O count and relay output capacity.
- 24 V DC supply.
- Display and clock needs.
- Program size and cycle time.
- Analogue inputs required.
- Extension or network needs (SR2 cannot extend).
Wiring and programming the SR2B121BD
Mount on rail or panel, wire the 24 V DC supply with polarity, the inputs and the relay outputs, then load the program from software or key it in. Use the backup memory to copy programs to other units.
Check that outputs match the program with a test, and use suppression on inductive loads to extend relay life.
Typical applications of the SR2B121BD in Oman and the GCC
Lighting control, small pumps and ventilation sequences, gate and door controls, and simple machine tasks in the region.
Dimensions, environment and approvals of the SR2B121BD
The SR2B121BD weighs 0.25 kg. Mounting, derating and enclosure choices follow the environmental data below, which should be compared with the actual panel temperature and the dust and humidity of the site in Oman and the GCC.
Ambient temperature limits in the datasheet: -20 to 40 °C in non-ventilated enclosure IEC 60068-2-1 and IEC. Relative humidity: 95 % without condensation or dripping water. Ingress protection: IP20 IEC 60529 terminal block; IP40 IEC 60529 front panel. Operating altitude: 2000 m. Standards listed: IEC 61000-4-12; IEC 61000-4-4 level 3; IEC 61000-4-5; IEC 61000-4-11; IEC 61000-4-2 level 3; IEC 60068-2-6 Fc; IEC 61000-4-6 level 3. Certifications listed for this reference: GL; CSA; UL; GOST; C-tick.
Information to send with an RFQ for the SR2B121BD
- Full reference and quantity required
- Existing equipment, panel or rack it must fit
- Supply voltage, load or signal details of the application
- Required delivery location and timing
- Whether a spare, a replacement or a new installation
Documents and quotation
A datasheet for this product is attached on this page. It lists the electrical, mechanical and environmental data summarised above.
Send us the part number, quantity and application and we will confirm availability and a quotation. Seven Star LLC is an independent supplier in Muscat and does not represent itself as an official channel of the manufacturer.
Datasheets & Documents
- Datasheet Schneider Electric SR2B121BD Datasheet Download
Reviews (0)
About brand
Schneider Electric is the French group for energy management and industrial automation: low and medium voltage switchgear and circuit breakers, motor control, drives, PLCs, power monitoring, UPS systems and building management. Its history goes back to 1836, when the brothers Adolphe and Eugène Schneider took over the iron and steel works at Le Creusot in Burgundy. Over the 20th century the company left steel and heavy engineering and became an electrical group through acquisitions such as Merlin Gerin, Télémécanique, Square D and Modicon. Its head office is in Rueil-Malmaison near Paris, and its shares are listed on Euronext Paris.
Schneider Electric company profile
| Origins | 1836, Le Creusot, France: Adolphe and Eugène Schneider take over the Le Creusot foundry |
|---|---|
| Headquarters | Rueil-Malmaison (Paris region), France |
| Ownership | Public company listed on Euronext Paris |
| Key acquisitions | Télémécanique (1988), Square D (1991), Merlin Gerin (1992), Modicon (1997), APC (2007), Invensys (2014); majority owner of AVEVA software |
| Brand names still in use | Acti9, ComPacT and MasterPacT breakers, TeSys motor control, Altivar drives, Altistart soft starters, Modicon PLCs, Harmony control components, PowerLogic and Easergy protection and metering, APC UPS, EcoStruxure software platform |
| Product families | Low voltage distribution, medium voltage switchgear and protection relays, motor control and drives, PLCs and HMIs, power meters, UPS and cooling, enclosures, building automation and energy software |
Milestones
- 1836: The Schneider brothers acquire the Le Creusot works; the business grows in steel, locomotives and heavy engineering.
- 1975: First investment in Merlin Gerin, a French maker of electrical distribution equipment.
- 1988–1992: Télémécanique, Square D (USA) and Merlin Gerin join the group, making it an electrical specialist.
- 1997: Modicon, the company behind the first programmable logic controller, joins the group.
- 1999: The group takes the name Schneider Electric.
- 2007 and 2014: APC (UPS and data centre power) and Invensys (process automation) are acquired.
Choosing Schneider Electric breakers and motor control
Circuit breakers are chosen by current and breaking capacity. Acti9 miniature circuit breakers (iC60, C120) protect final circuits up to 125 A. ComPacT NSX molded case breakers cover about 16 to 630 A, and the letter after the frame size sets the breaking capacity: B, F, N, H, S, L from lowest to highest. MasterPacT air circuit breakers are used as main incomers on large switchboards. For motors, a TeSys contactor with an LRD overload relay or a GV2 motor circuit breaker suits direct starting, an Altistart soft starter reduces starting current, and an Altivar drive controls speed. The breaking capacity must always be at least the prospective short-circuit current at the point of installation.
Where Schneider Electric products are used
In Oman and the GCC, Schneider Electric equipment is found in main and sub-main switchboards of commercial and residential buildings, motor control centres in water, oil and gas and industrial plants, substations protected by Sepam and Easergy relays, data centres powered by Galaxy and APC UPS systems, and buildings controlled by EcoStruxure Building Operation.
APC by Schneider Electric: UPS and critical power
Since 2007, APC has been part of Schneider Electric and is now its product brand for uninterruptible power supplies, replacement batteries, battery packs, network management cards and rack power distribution. Our APC catalogue covers Smart-UPS line-interactive and on-line models, Easy UPS On-Line, the modular Symmetra LX, RM and PX ranges, Silcon three-phase systems and their spare part kits, and the RBC cartridges that keep them running. Schneider Electric breakers, drives and PLCs can be quoted together with APC UPS systems in one request.
Schneider Electric products we list
| Family | Examples |
|---|---|
| Circuit breakers | Acti9 iC60N, C120N, NSX100F, NSX250N, NSX630, EasyPact EZC, MasterPacT MTZ1, MasterPacT NW |
| Motor control | TeSys Deca LC1D, TeSys F, LRD overload relay, GV2ME08, Altistart 22, Altistart 480 |
| Drives | Altivar 12, Altivar 320, ATV340, Altivar Process 630, ATV930, Lexium 32 servo |
| PLCs, HMIs and relays | Modicon M221, M241, M580 BMEP582040, Zelio Logic, Magelis HMISTU655 |
| Protection, metering and power | Sepam series 20, Easergy P3U30, MiCOM P139, PM5560, iEM3255, Galaxy VS UPS |
Ordering Schneider Electric products: what we need
Send the commercial reference from the label (for example LC1D18M7 or ATV320U22N4C). For breakers, confirm the rated current, number of poles, breaking capacity and trip unit. For contactors, give the coil voltage. For drives, give the motor power and supply voltage. APC products are listed on their own brand page.
Facts checked against Schneider Electric's published company history, October 2026.
Browse Schneider Electric products by category: Circuit Breaker, Electrical & Power Modules, AC Drives, PLC & I/O Cards, Metering Systems, UPS and Batteries.
FAQ
Questions about the Schneider Electric SR2B121BD Zelio SR2 Compact
Answers from our engineering team on installation, compatibility and integration.
01How many I/O has the SR2B121BD?
The datasheet lists inputs: 8 IEC 61131-2 Type 1.
02What supply does the SR2B121BD need?
Supply: 24 V DC.
03What is the cycle time?
Stated as 6 to 90 ms.
04What is the output current?
Listed: 8 A for all 4 outputs relay output.
05What clock backup has it?
Datasheet: 10 years 25 °C.
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