The **WJM-11A-R** is a specific model of a **magnetic proximity sensor** (often referred to as a reed switch sensor). These components are widely used in industrial automation for non-contact position sensing, limit switching, and object detection. ### 1. Technical Specifications Below are the typical electronic characteristics for this class of sensor: | Feature | Specification | | :--- | :--- | | **Sensor Type** | Magnetic Proximity / Reed Switch | | **Output Type** | SPST-NO (Normally Open) | | **Max Switching Voltage** | 100V - 250V AC/DC (varies by manufacturer) | | **Max Switching Current** | 100mA - 500mA | | **Contact Resistance** | < 200 mΩ | | **Operating Temperature** | -10°C to +70°C | | **Response Time** | < 1.0 ms | --- ### 2. Internal Components and Operation The WJM-11A-R operates based on magnetism rather than physical contact. * **The Reed Switch:** The core electronic part consists of two ferromagnetic blades (reeds) hermetically sealed in a glass envelope. * **Encapsulation:** The internal glass tube is encased in a durable plastic or resin housing to protect it from vibration and moisture. * **LED Indicator:** Many versions of the WJM-11A-R include a built-in LED (Red) in series with the switch to provide visual feedback when the circuit is closed. * **Protection Circuit:** It often includes a small resistor or varistor to protect the internal contacts against voltage spikes. --- ### 3. Wiring Configuration The device typically uses a 2-wire system. Because it is a "passive" switch, it acts like a bridge in the circuit. ```markdown [Power Source (+)] ---- [WJM-11A-R Sensor] ---- [Load/PLC Input] ---- [Common (-)] ``` > **Note:** When using this sensor with an inductive load (like a relay or solenoid), it is critical to install a **flyback diode** to prevent back-EMF from damaging the internal reed contacts. --- ### 4. Applications * **Pneumatic Cylinders:** Monitoring the stroke position of a piston. * **Security Systems:** Detecting if a door or window is closed. * **Safety Interlocks:** Ensuring a machine guard is in place before operation.