The **KUS-FW3-R** is an industrial-grade capacitive liquid level sensor, commonly used in automotive, marine, and generator applications to monitor fuel or water levels. Unlike traditional mechanical float switches, this sensor utilizes solid-state electronics to detect levels. ### 1. Core Specifications The electronic architecture of the KUS-FW3-R is defined by its resistance-based output and its capacitive sensing method. | Feature | Specification | | :--- | :--- | | **Input Voltage** | 12V / 24V DC | | **Output Signal** | Resistance (Standard 0-190 $\Omega$ or 240-33 $\Omega$) | | **Material** | SUS316 Stainless Steel (Body) | | **Protection Rank** | IP67 (Dust tight and waterproof) | | **Operating Temp** | -40°C to +85°C | --- ### 2. Key Electronic Components The device consists of several internal electronic layers: * **Capacitance-to-Digital Converter (CDC):** The sensor uses a central rod and an outer tube as electrodes. As the liquid level changes, the dielectric constant between these electrodes shifts. The internal CDC chip measures this change in capacitance. * **Microcontroller (MCU):** An internal low-power MCU processes the raw capacitance data, applies calibration curves, and compensates for temperature fluctuations. * **Signal Converter:** Since most analog gauges require resistance, the MCU controls a variable resistance circuit (often a digital potentiometer or a transistor-driven network) to mimic the behavior of a traditional mechanical rheostat. * **Filtering Circuitry:** Includes capacitors and inductors to filter out electromagnetic interference (EMI) and electrical noise commonly found in vehicle engine bays. --- ### 3. Wiring Configuration The KUS-FW3-R typically features a standard multi-wire lead for integration into a control system: 1. **Blue Wire:** Signal Ground (Connected to the gauge or negative terminal). 2. **Brown/Red Wire:** Signal Output (Sends the resistance value to the level gauge). 3. **Shielding:** High-quality sensors often include an internal shield to prevent static discharge from affecting the readings in volatile fluids like fuel. --- ### 4. Advantages of Electronic Sensing * **No Moving Parts:** Traditional floats suffer from mechanical wear; the FW3-R is solid-state, leading to a much longer lifespan. * **Precision:** Electronic calibration allows for a more linear output compared to the "steps" found in reed-switch sensors. * **Damping:** The internal electronics can digitally dampen the signal to prevent "needle bounce" on a gauge when the liquid is sloshing in a moving tank.