Siemens Sirius Safety relay, basic unit, 3NO + 1NC, 110 - 240VAC/DC Part number 3SK1111-1AW20

Product Overview

The Siemens 3SK1111-1AW20 is a basic safety-relay from the SIRIUS 3SK1 series. It is designed to monitor safety circuits (e.g. emergency-off, safety-door, or protective-guard interlocks) and to reliably provide safety switching outputs — making it suitable for machine safety, safeguarding enclosures, and emergency-stop systems according to industrial safety standards. The module offers multiple enabling outputs and a signalling contact, allowing safe and controlled switching of potentially hazardous machine circuits.

Key Features

• Safety relay — SIRIUS 3SK1 standard basic unit
• Supply voltage (Us): 110–240 V AC/DC, 50/60 Hz
• Safety enable outputs: 3 × NO contacts (safety-related enabling circuits)
• Signalling output: 1 × NC contact (non-safety signalling circuit)
• Supports protective-door monitoring, monitored or automatic start, and EMERGENCY-OFF / E-Stop functions
• Screw-terminal connections for reliable and secure wiring
• Narrow housing: width 22.5 mm — compact DIN-rail mounting
• Front-panel slide-switch for function selection and two LEDs for status indication / diagnostics
• Finger-safe terminals (enclosure rated IP20) — safe for enclosed control cabinets

Technical Specifications

• Article Number: 3SK1111-1AW20
• Product Type: SIRIUS 3SK1 safety relay, standard basic unit
• Supply Voltage (Us): 110–240 V AC / DC, 50/60 Hz
• Safety Enabling Outputs: 3 × NO (normally open) contacts
• Signalling Output: 1 × NC (normally closed) contact (non-safety)
• Function Features: Protective-door monitoring; monitored or automatic start; emergency-OFF / E-Stop monitoring; sensor inputs (floating sensor allowed)
• Input Configuration: 1-channel or 2-channel (for redundancy / cross-circuit detection)
• Protection Class: IP20 (finger-safe, enclosure required)
• Rated Insulation Voltage: 300 V
• Ambient Operating Temperature: –25 … +60 °C
• Storage Temperature: –40 … +80 °C
• Mechanical / Environmental Ratings: Vibration 5–500 Hz, 0.75 mm; Shock 10 g / 11 ms; Pollution degree 3; Surge withstand 4,000 V; EMC Class A device rating
• Mounting: 35 mm DIN rail, 22.5 mm enclosure width — compact installation size
• Performance Level / Safety Integrity Level (when used with compliant wiring): PL e (ISO 13849-1), SIL 3 (IEC 61508 / 62061)

Compliance & Standards

• Meets safety-relay requirements per IEC / EN standards for emergency-off / protective-guard monitoring (EN 60204-1 / ISO 13850 etc.)
• Performance level up to PL e according to ISO 13849-1 (when correctly applied with safety wiring)
• Suitable for use in safety-related circuits, conforming to relevant industrial safety norms

Applications

The 3SK1111-1AW20 is ideal for safety-circuit applications such as emergency stop (E-Stop), protective-door monitoring, safety interlocks, guarded areas, and machine safety interfaces. Use cases include guarding enclosures, guarding machinery access doors, integrating safety sensors (light barriers, safety switches), and ensuring safe shut-off of hazardous machine parts. It is appropriate for factory automation, processing plants, safety control panels, machinery safety circuits and any environment where functional safety and operator protection are required.