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Schneider Electric SR2B121BD

Schneider SR2B121BD Zelio Logic Smart Relay, 24 VDC, RTC

MPNSR2B121BD
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Schneider Electric Zelio Logic compact smart relay, 24 V DC, 8 discrete inputs, relay outputs, built-in real-time clock.

$78.74Ref. price · indicative, final on quote
Schneider Electric SR2B121BD datasheet (PDF)
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MOQ1 pcs
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Jul 2026
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Specifications

SR2B121BD key specifications
ParameterValue
Range of productZelio Logic
Discrete input typeResistive
Product or component typeCompact smart relay
Supply voltage limits19.2...30 V
Discrete input voltage24 V DC
Supply voltage24 V DC
Voltage state 0 guaranteed= 1.2 mA IB...IG used as discrete input circuit) >= 2.2 mA I1...IA and IH...IR discrete input circuit)
Voltage state 1 guaranteed>= 15 V I1...IA and IH...IR discrete input circuit >= 15 V IB...IG used as discrete input circuit
[Uimp] rated impulse withstand voltage4 kV EN/IEC 60947-1 and EN/IEC 60664-1
Discrete input current4 mA
Maximum supply current100 mA without extension)
Current state 0 guaranteed= 10 mA 12 V relay output)

All specifications

SR2B121BD additional specifications
ParameterValue
Power dissipation in3 W without extension
Counting frequency1 kHz discrete input
Operating rate in0.1 Hz at Ie)relay output 10 Hz no load)relay output
IP degree of protectionIP20 IEC 60529 terminal block) IP40 IEC 60529 front panel)
Connections - terminalsScrew terminals, 1 x 0.2...1 x 2.5 mm² AWG 25...AWG 14) semi-solid Screw terminals, 1 x 0.2...1 x 2.5 mm² AWG 25...AWG 14) solid Screw terminals, 1 x 0.25...1 x 2.5 mm² AWG 24...AWG 14) flexible with cable end Screw terminals, 2 x 0.2...2 x 1.5 mm² AWG 24...AWG 16) solid Screw terminals, 2 x 0.25...2 x 0.75 mm² AWG 24...AWG 18) flexible with cable end
Response time10 ms from state 0 to state 1)relay output 5 ms from state 1 to state 0)relay output
Pollution degree2 IEC 61131-2
Relative humidity95 % without condensation or dripping water
Operating altitude6561.68 ft (2000 m)
Maximum altitude transport10000 ft (3048 m)
Mechanical durability10000000 cycles relay output
StandardsIEC 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 IEC 60068-2-27 Ea IEC 61000-4-3
ClockWith
ChecksProgram memory on each power up
CategoryUS1000I22378
Cycle time6...90 ms
Backup time10 years 77 °F (25 °C)
Clock drift12 min/year 32...131 °F (0...55 °C) 6 s/month 77 °F (25 °C)
Local displayWith
Tightening torque4.4 lbf.in (0.5 N.m)
Overvoltage categoryIII conforming to IEC 60664-1
Discrete input number8 IEC 61131-2 Type 1
Immunity to microbreaks1 ms
Reverse polarity protectionWith
Environmental characteristicEMC directive conforming to IEC 61000-6-2 EMC directive conforming to IEC 61000-6-3 EMC directive conforming to IEC 61000-6-4 EMC directive conforming to IEC 61131-2 zone B Low voltage directive conforming to IEC 61131-2
Disturbance radiated (conducted)Class B EN 55022-11 group 1
Number or control scheme lines0...240 ladder 0...500 FBD
Ambient air temperature for storage-40...158 °F (-40...70 °C)
Ambient air temperature for operation-4...104 °F (-20...40 °C) in non-ventilated enclosure IEC 60068-2-1 and IEC 60068-2-2 -4...131 °F (-20...55 °C) IEC 60068-2-1 and IEC 60068-2-2

Product details

Compact smart relay with RTC and program integrity check

The SR2B121BD is a Schneider Zelio Logic compact smart relay running at 24 VDC, packing 8 discrete inputs per IEC 61131-2 Type 1 and relay outputs. It carries a built-in real-time clock (: Clock: With) that is battery-backed for 10 years at 77 °F (: Backup time). On each power-up the unit runs a program memory check (: Checks: Program memory on each power up) to verify the ladder/FBD logic hasn't corrupted. Cycle time spans 6...90 ms, adequate for most conveyor, pump, or light-curtain sequences. Response time from input transition to relay output is 10 ms for 0→1 and 5 ms for 1→0. Discrete inputs are resistive type, 4 mA at 24 VDC, and the unit draws under 100 mA without expansion modules.

Relay outputs are rated for a mechanical durability of 10 million cycles, but the maximum operating rate is 0.1 Hz at rated current (Ie) and 10 Hz at no load. That matters if you're switching a contactor coil at high speed — stay within the 0.1 Hz limit under load to avoid premature weld. Environment: Pollution degree 2, overvoltage category III, IP20 on terminals and IP40 on front panel. It withstands the IEC immunity suite — levels 3 for fast transients and ESD, plus surge and conducted RF. Disturbance radiated/conducted is Class B, group 1, so it's fine for residential/commercial panels, not just industrial zones. Supply voltage limits are 19.2...30 V on the nominal 24 VDC rail, with reverse polarity protection. Power dissipation stays at 3 W without extension. Screw terminals accept 1 x 0.2 to 2.5 mm² solid or stranded, and tightening torque is 0.5 N·m.

Compliance documentation

The SR2B121BD is designed to meet IEC 61131-2 (programmable controllers), IEC 61000-6-2/3/4 (EMC), and Low Voltage Directive. It also carries IEC 60068 vibration/shock ratings. RoHS/REACH declarations are available upon request; these are not in the standard spec publication but are part of the Schneider compliance pack for active catalog items.

Frequently asked questions

What is SR2B121BD's listed clock specification?

The unit includes a real-time clock (: Clock: With). Backup time is 10 years at 77 °F (25 °C), and clock drift is 6 s/month at 77 °F.

What program integrity checks does SR2B121BD perform?

On every power-up, it runs a program memory check (: Checks: Program memory on each power up) to verify the stored ladder/FBD logic is uncorrupted before executing the cycle.

What compliance standards does SR2B121BD meet?

It conforms to IEC 61131-2 (programmable controller), IEC 61000-6-2/3/4 (EMC), and Low Voltage Directive. Immunity includes IEC 61000-4-2 level 3, IEC 61000-4-4 level 3, IEC 61000-4-5, IEC 61000-4-11, and IEC 61000-4-6 level 3. Radiated/conducted emissions are Class B, group 1.

MPN
SR2B121BD