The **V-2121-R** refers to a specific model of a **Miniature Basic Microswitch**, typically manufactured by Omron (though the part numbering logic is consistent across similar industrial switch brands). These switches are used as sensors or limit switches in appliances, machinery, and automation. --- ### 1. Breakdown of Part Number (V-2121-R) The nomenclature defines the electrical and mechanical characteristics of the switch: | Part Segment | Meaning | Technical Specification | |:---|:---|:---| | **V** | Switch Series | High-capacity basic switch series. | | **21** | Current Rating | Rated for **21 Amps** at 250VAC. | | **2** | Contact Gap | G-gap (0.5mm) - standard for high current. | | **1** | Actuator Type | **Short Hinge Roller Lever**. | | **-R** | Terminal Type | **Right-hand angled** or Reverse-acting (depends on specific sub-series). | --- ### 2. Key Electronic & Physical Components #### A. Internal Contact Mechanism The switch utilizes a **Snap-Action** mechanism. This means that regardless of how slowly the external lever is pressed, the internal contacts snap together or apart at a high speed to prevent electrical arcing. * **Common (COM):** The input terminal. * **Normally Closed (NC):** The circuit is complete when the lever is up. * **Normally Open (NO):** The circuit completes only when the lever is pressed. #### B. Electrical Ratings The V-21 series is designed for heavy-duty power switching: * **Voltage:** Up to 250V AC. * **Current:** 21A (Resistive load). * **Insulation Resistance:** 100 MΩ min. at 500V DC. * **Contact Resistance:** 15 mΩ max. (initial value). #### C. Actuator: Short Hinge Roller Lever This specific part features a small wheel (roller) at the end of a short metal arm. This is electronically significant because it reduces friction and allows the switch to be triggered by a **cam** or a sliding part moving across it, rather than just a direct vertical press. --- ### 3. Connection Schematic Typical wiring for a V-series microswitch: ```mermaid graph LR A[Power Source] --> B(COM Terminal) B --> C{Switch State} C -- Lever Pressed --> D(NO Terminal - Load ON) C -- Lever Released --> E(NC Terminal - Load ON) ``` --- ### 4. Technical Specifications Summary | Feature | Specification | |:---|:---| | **Operating Force (OF)** | Approx. 1.23 N to 3.92 N (Depending on lever length) | | **Durability (Mechanical)** | 50,000,000 operations min. | | **Durability (Electrical)** | 100,000 operations min. | | **Housing Material** | Thermosetting resin (Heat resistant) | | **Contact Material** | Silver Alloy |