The **MLS-2B-R/E** is a specific type of high-frequency **Magnetic Proximity Sensor** (often referred to as a "Door Switch" or "Actuator Unit") commonly used in industrial automation, elevator systems, and security hardware. Below is a detailed breakdown of its electronic characteristics and components. --- ### 1. General Specifications The MLS-2B-R/E functions primarily as a non-contact switch that reacts to the presence of a magnetic field. | Feature | Specification | | :--- | :--- | | **Contact Form** | Normally Open (NO) / Normally Closed (NC) depending on wiring | | **Max Voltage** | 100V DC / 125V AC | | **Max Current** | 0.5A | | **Contact Capacity** | 10W | | **Operating Temperature** | -10°C to +60°C | | **Housing Material** | ABS Plastic / Resin | --- ### 2. Core Electronic Components The internal architecture of the MLS-2B-R/E is relatively simple but precision-engineered for reliability. #### A. Reed Switch The heart of the device is a **hermetically sealed glass reed switch**. - It consists of two ferromagnetic blades (reeds). - When a magnetic field (from the actuator) is brought near, the reeds become polarized and pull together, closing the circuit. - The "R/E" designation often implies a **Rhodium-plated** or **Ruthenium-plated** contact surface to prevent welding and ensure a high cycle life (often over 1 million operations). #### B. Internal Resistors (Optional in some variants) Some sub-models of the MLS-2B series include internal **End-of-Line (EOL) resistors**. - These allow the control panel to distinguish between a "closed door," an "open door," and a "tampered/cut wire." #### C. Protective Diode/Varistor In versions used for inductive loads, a small internal diode may be present to prevent back-EMF (voltage spikes) from damaging the reed switch when the circuit is opened. --- ### 3. Wiring and Connection Logic The device typically uses a multi-core cable. The "2B" designation usually refers to the contact configuration. | Wire Color (Standard) | Function | Description | | :--- | :--- | :--- | | **Black** | Common (COM) | The shared terminal for the switch. | | **White** | Normally Open (NO) | Closes when the magnet is present. | | **Red** | Normally Closed (NC) | Opens when the magnet is present. | --- ### 4. Key Performance Factors * **Operating Distance (Sn):** The distance at which the switch activates. For the MLS-2B, this is usually between **15mm to 25mm**. * **Hysteresis:** The difference between the "make" point and the "break" point. This prevents "chatter" (rapid flickering) if the door or actuator vibrates. * **Environmental Sealing:** The electronics are typically **potted in epoxy resin**, making the unit resistant to moisture, dust, and vibration. --- ### 5. Common Applications * **Elevator Doors:** Monitoring if the inner and outer doors are aligned and locked. * **Industrial Safety:** Ensuring machine guards are closed before a motor can start. * **Access Control:** High-durability door position monitoring for security systems.