The **3SB 4-R** refers to a specific series of industrial control devices, primarily manufactured by **Siemens** under the **SIRIUS 3SB** family. Specifically, this designation usually points to a **round, red emergency stop (E-Stop) pushbutton** or a pilot light indicator, depending on the exact sub-variant. --- ## 1. Component Overview The 3SB series is designed for heavy-duty industrial environments, ensuring reliable human-machine interface (HMI) interaction. The "4-R" designation typically identifies the physical characteristics and the color. | Feature | Specification | | :--- | :--- | | **Series** | SIRIUS 3SB3 (standard 22mm) | | **Diameter** | 22 mm mounting hole | | **Color** | Red (R) | | **Actuator Type** | Mushroom head / Emergency Stop | | **Material** | Plastic or Metal (depending on suffix) | | **Ingress Protection** | IP66 / IP67 (Dust tight and waterproof) | --- ## 2. Electrical Characteristics The device itself is an **actuator**. To function electronically, it must be paired with **Contact Blocks**. ### Contact Configurations The electronic behavior depends on the contact blocks clipped to the back of the 3SB 4-R: * **NC (Normally Closed):** Used for safety circuits (Emergency Stop). When the button is pressed, the circuit opens. * **NO (Normally Open):** Used for start signals or status indicators. ### Technical Ratings * **Rated Operational Voltage ($U_e$):** Typically up to 500V AC or 230V DC. * **Thermal Current ($I_{th}$):** Generally rated for 10A. * **Switching Frequency:** Mechanical life of approximately $3 \times 10^5$ operating cycles. --- ## 3. Physical & Electronic Assembly The 3SB 4-R is a modular system consisting of three main parts: 1. **Actuator (The 4-R head):** The visible red part the operator presses. 2. **Holder:** The bracket that secures the actuator to the control panel. 3. **Contact Block/Lampholder:** The electronic component where wires are connected. If the unit is an indicator, it contains an **LED** or **Incandescent** bulb. --- ## 4. Common Application Wiring In a safety circuit, the 3SB 4-R (Red E-Stop) is wired in series with the coil of a contactor: ```mermaid graph LR Power[L1] --> EStop[3SB 4-R NC Contact] EStop --> StopBtn[Stop Button] StopBtn --> Contactor[Motor Contactor Coil] Contactor --> Neutral[N] ``` ### Key Safety Standards * **EN ISO 13850:** Complies with safety requirements for emergency stop functions. * **IEC 60947-5-1:** Standard for low-voltage switchgear and controlgear.