The **KUS-K4-R** typically refers to a high-precision, industrial-grade **resistive fuel/water level sensor** manufactured by KUS (formerly Wema). This specific model is widely used in marine, automotive, and generator applications to monitor tank levels. Below is a detailed explanation of its electronic components and specifications. --- ### 1. Internal Working Principle The KUS-K4-R operates on a **reed switch and resistor ladder** mechanism. Unlike capacitive sensors that measure electrical fields, this is a mechanical-electronic hybrid: * **The Float:** Contains a permanent magnet. * **The Stem:** Houses a series of hermetically sealed reed switches and fixed-value resistors. * **Action:** As the float rises or falls with the liquid level, the magnetic field closes specific reed switches, changing the total resistance of the circuit. ### 2. Electronic Specifications The "R" in the model name usually signifies a specific resistance range. In the marine industry, there are two dominant standards: | Feature | Specification (Standard) | | :--- | :--- | | **Signal Output** | Resistance-based (0-190Ω or 240-33Ω) | | **Input Voltage** | Passive (Uses the gauge's reference voltage) | | **Switching Resolution** | 10mm to 21mm (depending on length) | | **Material** | SUS 316 Stainless Steel | | **Operational Temp** | -40°C to +85°C | | **Protection Rating** | IP67 (Dust and Water tight) | ### 3. Wiring Configuration The electronic interface of the KUS-K4-R is straightforward, typically consisting of a 2-wire system: ```markdown - Brown Wire: Signal Output (To the Gauge) - Blue Wire: Ground (Negative/Earth) ``` ### 4. Key Advantages * **Linearity:** The resistor ladder ensures a stepped but linear output that gauges can easily interpret. * **Durability:** Because the reed switches are encased in a stainless steel tube and the float is the only moving part, there is no direct contact between the liquid and the electronic circuit. * **No Calibration:** Unlike ultrasonic or capacitive sensors, the K4 series is factory-set and does not require complex electronic calibration. --- ### Comparison: K4-R vs. Electronic Digital Sensors | Feature | K4-R (Resistive) | Digital (NMEA 2000) | | :--- | :--- | :--- | | **Data Format** | Analog Ohms | Digital Data Packets | | **Complexity** | Low (2 wires) | High (5-pin Micro-C) | | **Compatibility** | Standard Analog Gauges | Chartplotters / MFDs |