The **3SB3 series** (specifically the 3SB3-R variants) refers to a legacy but widely used line of industrial control devices manufactured by **Siemens**. These are modular 22mm command and signaling devices used to interface between human operators and electrical control systems. --- ### 1. Overview of the 3SB3-R Series The "R" in 3SB3-R typically signifies the **Round** design variant (made of plastic or metal), as opposed to square designs. These components are designed for heavy-duty industrial environments. ### 2. Core Electronic and Mechanical Components A complete 3SB3 assembly is modular and consists of three primary parts: | Component | Description | Function | | :--- | :--- | :--- | | **Actuator** | The visible part (button, switch, or lamp). | Receives physical input from the user. | | **Holder** | The mounting bracket. | Secures the actuator to the control panel and holds contact blocks. | | **Contact Block** | The electrical switching element. | Opens or closes the electrical circuit. | | **LED/Lamp Block** | The illumination element. | Provides visual feedback (for pilot lights or illuminated buttons). | --- ### 3. Electrical Specifications The electronic behavior of these parts is defined by their contact reliability and voltage ratings: * **Switching Capacity:** Usually rated for **AC-15** (heavy inductive loads) and **DC-13** (solenoids). * **Voltage Range:** * *Contacts:* Up to 400V AC/DC. * *LED Modules:* Available in 24V AC/DC, 110V AC, or 230V AC. * **Contact Types:** * **NO (Normally Open):** Circuit closes when pressed. * **NC (Normally Closed):** Circuit opens when pressed (often used for E-Stops). --- ### 4. Technical Comparison: Plastic vs. Metal (3SB3-R) Siemens offered the round series in two distinct materials depending on the environmental requirements: | Feature | 3SB3 (Plastic) | 3SB3 (Metal) | | :--- | :--- | :--- | | **Bezel Material** | Black Plastic | Polished Chrome or Matte Aluminum | | **Durability** | High (Standard) | Extreme (Chemical/Impact resistant) | | **Mounting Diameter** | 22.5 mm | 22.5 mm | | **Protection Class** | IP65/IP66 | IP67 / NEMA 4X | --- ### 5. Lifecycle Note: Sirius Act (3SU1) It is important for engineers and buyers to note that the **3SB3 series has been discontinued** by Siemens. It has been replaced by the **SIRIUS ACT (3SU1)** series. * **Retrofitting:** While 3SU1 is the successor, the parts are not always directly interchangeable without an adapter, though they fit the same 22.5mm hole. * **Electronic Compatibility:** The new 3SU1 series offers modern electronic integration like **AS-Interface, IO-Link, and PROFINET** connectivity, which was limited in the older 3SB3 line. ---