The **47LM-102B-R** is a specific model within a series of **LVDT (Linear Variable Differential Transformer)** displacement transducers, typically manufactured by companies like Measurement Specialties (TE Connectivity). These sensors are designed to measure linear position or displacement with high precision and durability in industrial or laboratory environments. --- ## Technical Specifications The "47LM" series generally refers to a specific body diameter and stroke range. Below are the typical characteristics of this component: | Parameter | Description | | :--- | :--- | | **Sensor Type** | LVDT (Linear Variable Differential Transformer) | | **Measurement Range** | ± 1.0 inch (approx. 25.4 mm) | | **Input Voltage** | 3.0 Vrms (nominal) | | **Frequency Range** | 400 Hz to 5 kHz | | **Linearity** | ± 0.25% of Full Scale (standard) | | **Operating Temp** | -55°C to +150°C (wide range) | | **Construction** | Stainless Steel housing / Magnetically shielded | --- ## Electronic Components & Working Principle An LVDT like the 47LM-102B-R consists of three main internal electromagnetic coils: 1. **Primary Coil:** Located at the center of the housing. When an AC excitation signal is applied, it creates a varying magnetic field. 2. **Secondary Coils (S1 & S2):** Two identical coils placed symmetrically on either side of the primary. They are wired in **series-opposition**. 3. **Ferromagnetic Core:** A movable rod that slides inside the hollow center of the coils. ### How it Works: * **Null Position:** When the core is exactly in the center, the voltage induced in both secondary coils is equal but opposite, resulting in a **zero output**. * **Displacement:** As the core moves toward S1, the mutual inductance increases for S1 and decreases for S2. This creates a differential voltage proportional to the distance moved. * **Phase Shift:** The phase of the output signal relative to the input indicates the *direction* of movement. --- ## Key Features * **Frictionless Measurement:** Since the core does not touch the coils, there is no mechanical wear, leading to an infinite mechanical life. * **Infinite Resolution:** Because it operates on electromagnetic principles rather than discrete steps, the resolution is limited only by the external signal conditioning electronics. * **Ruggedness:** The "R" suffix often denotes a **Ruggedized** or RoHS-compliant version, ensuring it can withstand vibrations and harsh industrial fluids. --- ## Connection Diagram (Typical) Most 47LM units use a 6-wire or 4-wire configuration: ```text Primary (Excitation): Red/Black (or White) Secondary 1: Yellow Secondary 2: Blue Center Tap/Common: Green/Black ```