The **MEWT-320-R** is a specific model of an **Electronic Liquid Level Sensor/Transmitter**, commonly used in industrial automation for monitoring fluid levels in tanks or reservoirs. Below is a breakdown of its primary electronic components, specifications, and functional architecture. ### 1. Key Technical Specifications | Parameter | Description | | :--- | :--- | | **Sensing Principle** | Float-operated magnetic reed switch or Magnetostrictive (model dependent) | | **Output Signal** | 4-20mA Analog (standard) | | **Input Voltage** | 12V to 24V DC | | **Resolution** | High precision (usually 5mm to 10mm increments) | | **Protection Class** | IP65 / IP67 (Waterproof/Dustproof) | --- ### 2. Primary Electronic Components The internal circuitry of the MEWT-320-R consists of three main stages: #### A. The Sensing Element (The Probe) * **Reed Switch Array:** Inside the stem, there is a series of glass-encapsulated reed switches and resistors. * **Magnetic Float:** A buoyant ring containing a permanent magnet moves along the stem. As it moves, the magnetic field closes specific switches. #### B. The Signal Converter (PCBA) Located in the "head" or junction box of the unit, this board translates mechanical position into an electrical signal: * **Resistor Ladder:** The activated reed switches change the total resistance of a circuit. * **A/D Converter/Operational Amplifier:** This converts the varying resistance into a stable current loop (4-20mA). * **Filtering Capacitors:** These are used to reduce "slosh" noise (electronic jitter caused by turbulent liquid). #### C. Connectivity and Protection * **Zener Diodes:** Often included for surge protection and to prevent damage from reverse polarity. * **Terminal Block:** A 2-wire or 3-wire connection point for power and signal output. --- ### 3. Functional Wiring Diagram The device typically follows a standard current loop configuration: ```mermaid graph LR Power_Source[24V DC Supply] -->|Positive| Sensor[MEWT-320-R] Sensor -->|4-20mA Signal| Controller[PLC / Digital Display] Controller -->|Return| Power_Source ``` ### 4. Typical Applications * **Oil & Fuel Tanks:** Monitoring levels in hazardous or remote locations. * **Water Treatment:** Controlling pump start/stop cycles based on tank volume. * **Chemical Processing:** Using the corrosion-resistant housing to monitor acidic or alkaline fluids. ---