• Siemens SIRIUS 3SK1 Advanced Safety Relays (3SK1120, 3SK1121, 3SK1122)
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Siemens SIRIUS 3SK1 Advanced Safety Relays (3SK1120, 3SK1121, 3SK1122)

Siemens SIRIUS 3SK1 Advanced Safety Relays (3SK1120, 3SK1121, 3SK1122)

SIRIUS 3SK1 Advanced basic safety relays that can be expanded with inputs and outputs via 3ZY12 device connectors without extra wiring.

Key features

  • Up to SIL 3 (IEC 62061) and PL e (ISO 13849-1)
  • Use of 3ZY12 device connectors possible for sensor and output expansion
  • Relay outputs (3SK1121) or semiconductor outputs (3SK1120, 3SK1122)
  • Versions with adjustable OFF-delay: 0.05-3 s, 0.5-30 s or 5-300 s
  • Parameterization via DIP switches
  • Screw or spring-loaded (push-in) terminals

Specifications

Brand Siemens
Product line SIRIUS 3SK1 Advanced
Control supply voltage 24 V DC
Ambient temperature -25 ... +60 °C
Degree of protection IP20
Safety level SIL 3 / PL e
Approvals UL, TÜV
Mounting 35 mm DIN rail
Source Siemens Catalog IC 10 · 2026, p. 1053-1056
3SK1121-1AB40 Type: 3SK1121 Advanced | Outputs: 3 NO + 1 NC signaling (relay) | OFF-delay: None | Connection: Screw
3SK1121-2AB40 Type: 3SK1121 Advanced | Outputs: 3 NO + 1 NC signaling (relay) | OFF-delay: None | Connection: Spring-loaded (push-in)
3SK1121-1CB41 Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.05 ... 3 s | Connection: Screw
3SK1121-2CB41 Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.05 ... 3 s | Connection: Spring-loaded (push-in)
3SK1121-1CB42 Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.5 ... 30 s | Connection: Screw
3SK1121-2CB42 Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.5 ... 30 s | Connection: Spring-loaded (push-in)
3SK1121-1CB44 Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 5 ... 300 s | Connection: Screw
3SK1121-2CB44 Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 5 ... 300 s | Connection: Spring-loaded (push-in)
3SK1120-1AB40 Type: 3SK1120 Advanced | Outputs: 1 safety (semicond.) | OFF-delay: None | Connection: Screw
3SK1120-2AB40 Type: 3SK1120 Advanced | Outputs: 1 safety (semicond.) | OFF-delay: None | Connection: Spring-loaded (push-in)
3SK1122-1AB40 Type: 3SK1122 Advanced | Outputs: 3 safety + 1 signaling (semicond.) | OFF-delay: None | Connection: Screw
3SK1122-2AB40 Type: 3SK1122 Advanced | Outputs: 3 safety + 1 signaling (semicond.) | OFF-delay: None | Connection: Spring-loaded (push-in)
3SK1122-1CB41 Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.05 ... 3 s | Connection: Screw
3SK1122-2CB41 Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.05 ... 3 s | Connection: Spring-loaded (push-in)
3SK1122-1CB42 Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.5 ... 30 s | Connection: Screw
3SK1122-2CB42 Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.5 ... 30 s | Connection: Spring-loaded (push-in)
3SK1122-1CB44 Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 5 ... 300 s | Connection: Screw
3SK1122-2CB44 Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 5 ... 300 s | Connection: Spring-loaded (push-in)
Safety RelaysSiemens
18 product codes available in this family
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Siemens SIRIUS 3SK1 Advanced Safety Relays (3SK1120, 3SK1121, 3SK1122)

Brand Siemens·Safety Relays

Available part numbers (18)

3SK1121-1AB40, 3SK1121-2AB40, 3SK1121-1CB41, 3SK1121-2CB41, 3SK1121-1CB42, 3SK1121-2CB42, 3SK1121-1CB44, 3SK1121-2CB44, 3SK1120-1AB40, 3SK1120-2AB40 + 8 more — see full table ↓

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Product codes & specifications
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Product codeSpec
3SK1121-1AB40Type: 3SK1121 Advanced | Outputs: 3 NO + 1 NC signaling (relay) | OFF-delay: None | Connection: Screw
3SK1121-2AB40Type: 3SK1121 Advanced | Outputs: 3 NO + 1 NC signaling (relay) | OFF-delay: None | Connection: Spring-loaded (push-in)
3SK1121-1CB41Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.05 ... 3 s | Connection: Screw
3SK1121-2CB41Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.05 ... 3 s | Connection: Spring-loaded (push-in)
3SK1121-1CB42Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.5 ... 30 s | Connection: Screw
3SK1121-2CB42Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 0.5 ... 30 s | Connection: Spring-loaded (push-in)
3SK1121-1CB44Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 5 ... 300 s | Connection: Screw
3SK1121-2CB44Type: 3SK1121 Advanced | Outputs: 2 NO instant. + 2 NO delayed (relay) | OFF-delay: 5 ... 300 s | Connection: Spring-loaded (push-in)
3SK1120-1AB40Type: 3SK1120 Advanced | Outputs: 1 safety (semicond.) | OFF-delay: None | Connection: Screw
3SK1120-2AB40Type: 3SK1120 Advanced | Outputs: 1 safety (semicond.) | OFF-delay: None | Connection: Spring-loaded (push-in)
3SK1122-1AB40Type: 3SK1122 Advanced | Outputs: 3 safety + 1 signaling (semicond.) | OFF-delay: None | Connection: Screw
3SK1122-2AB40Type: 3SK1122 Advanced | Outputs: 3 safety + 1 signaling (semicond.) | OFF-delay: None | Connection: Spring-loaded (push-in)
3SK1122-1CB41Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.05 ... 3 s | Connection: Screw
3SK1122-2CB41Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.05 ... 3 s | Connection: Spring-loaded (push-in)
3SK1122-1CB42Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.5 ... 30 s | Connection: Screw
3SK1122-2CB42Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 0.5 ... 30 s | Connection: Spring-loaded (push-in)
3SK1122-1CB44Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 5 ... 300 s | Connection: Screw
3SK1122-2CB44Type: 3SK1122 Advanced | Outputs: 2 instant. + 2 delayed (semicond.) | OFF-delay: 5 ... 300 s | Connection: Spring-loaded (push-in)

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