Siemens 3RK1105-1AE04-0CA0 SIRIUS Safety Relay for Emergency Stop and Guard Monitoring

The Siemens 3RK1105-1AE04-0CA0 is a compact safety relay from the SIRIUS 3RK1 series. It is designed to monitor emergency stop pushbuttons, safety door switches, light curtains, and two-hand control devices. The module provides two redundant safety outputs (forced-guided relays) and one auxiliary output for status indication. It meets the requirements of SIL3 (IEC 61508) and PLe (ISO 13849-1), making it suitable for Category 4 safety circuits up to PL e.

Input and Output Specifications

The 3RK1105-1AE04-0CA0 features two dual-channel safety inputs (suitable for devices with mechanical contacts or OSSD outputs) and one start input (auto-start or monitored manual reset). The safety outputs are two NO (normally open) forced-guided relays rated at 6 A (250 VAC/24 VDC). The auxiliary output is one NC (normally closed) relay contact. All outputs are isolated from the input circuits. The response time (from input change to output de-energization) is ≤ 20 ms.

Functional Safety Features

The relay implements cross-circuit monitoring, short-circuit detection, and contact welding detection. For emergency stop applications, it supports single-channel or dual-channel wiring with redundancy. In dual-channel mode, both input channels must close within 200 ms of each other; otherwise a fault is detected. The start circuit can be configured for automatic start (bridge across S11-S12) or monitored manual start (pushbutton across S11-S12 with edge detection). The module also features a feedback loop (Y1-Y2) to monitor external contactors.

Configuration and Diagnostics

No software configuration is required; all settings are made via DIP switches on the front panel. Switches allow selection of: single/dual channel, with/without cross-circuit detection, auto/manual reset, and feedback loop enable/disable. LED indicators provide status: green (power), yellow (input status), red (fault or output off). The module also includes a test output (T1, T2) for checking external wiring integrity. Diagnostic information can be read via the auxiliary contact or through a higher-level controller using the optional communication module (not included).

Mechanical and Environmental Ratings

The housing is rated IP20 and measures 100mm (H) x 22.5mm (W) x 120mm (D), occupying just one standard modular width. It mounts on 35mm DIN rail (EN 60715). Operating temperature: -25°C to +60°C, storage -40°C to +85°C. Humidity: 5% to 95% non-condensing. The relay is vibration tested to 2G (10-150 Hz) and shock resistance of 15G (11 ms). It meets CE, UL, TÜV, and CCC certifications. The 3RK1105-1AE04-0CA0 is RoHS compliant and suitable for use in pollution degree 2 environments.

Wiring Examples

Typical wiring: connect 24 VDC to A1 and A2. For an emergency stop with dual-channel, wire two NC contacts in series between S11 and S12, and between S12 and S22? Actually the manual: S11-S12 is channel 1, S21-S22 is channel 2. Both channels must be closed to energize the outputs. The start button connects between S33 and S34. The feedback loop connects from Y1 to Y2 through external contactor’s NC auxiliary contacts. The safety outputs (13-14, 23-24) are wired to the main contactor coils.

Typical Applications

Common uses include: emergency stop circuits on packaging machines, safety door monitoring on robotic cells, light curtain muting in presses, and two-hand control on hydraulic presses. The small width saves panel space, and the ability to monitor both inputs and external contactors makes it a flexible choice for machine builders requiring SIL3/PLe compliance. It is often paired with Siemens AS-i safety monitors or integrated into SIMATIC safety systems via PROFIsafe (using the 3RK1105-1AE04-0CA0 as a standalone device).

Ordering and Replacement

Order number: 3RK1105-1AE04-0CA0. The relay is supplied with a terminal cover and labeling strip. Replacement units must have the same order number to maintain safety certification. For applications requiring higher output current, external contactors must be used because the internal relays are rated 6A. Siemens provides a detailed manual (3RK1105 Manual) with wiring diagrams and safety validation examples. The product life cycle is active as of 2025, with spare parts available for at least 10 years.