The **FCR-3A-R** is a specific model within a series of compact, digital PID temperature controllers (often manufactured by companies like Shinko Technos). It is designed for panel mounting and industrial process control. Below is a breakdown of its electronic components, specifications, and functions. --- ### 1. Technical Specifications The "FCR" series is known for its space-saving design and reliability. The specific suffix (3A-R) typically denotes the control output type and physical dimensions. | Feature | Description | | :--- | :--- | | **Control Method** | PID control with Auto-tuning or ON/OFF control | | **Input Type** | Multi-input (Thermocouple K, J, R, S, B, E, T, N, PL-II, WRe5-26; RTD Pt100, JPt100) | | **Output Type (R)** | **Relay Contact** (1a contact, 250V AC 3A) | | **Power Supply** | 100 to 240V AC (standard) or 24V AC/DC (optional) | | **Sampling Cycle** | Approx. 0.25 seconds | | **Display** | 4-digit Red LED (Process Value) | --- ### 2. Core Electronic Parts & Modules The internal architecture of the FCR-3A-R consists of several key electronic sections: #### A. Microprocessor (The Brain) The unit uses an integrated MCU to handle PID algorithms. It calculates the difference between the Set Point (SV) and the Process Value (PV) to determine the output pulse width. #### B. Input Conditioning Circuit * **A/D Converter:** High-resolution analog-to-digital converter to translate millivolt signals (from thermocouples) or resistance changes (from RTDs) into digital data. * **Cold Junction Compensation (CJC):** A thermistor located near the terminal block to compensate for ambient temperature changes at the connection point. #### C. Power Supply Section * **Switching Mode Power Supply (SMPS):** Most models use a compact SMPS to step down mains voltage (100-240V) to internal low-voltage DC (5V or 3.3V) for the logic circuits. #### D. Control Output (The "R" Suffix) * **Mechanical Relay:** The "R" in the model name stands for **Relay**. It is a physical electromagnetic switch. * **Protection:** Often includes a snubber circuit to reduce arcing when switching inductive loads. --- ### 3. Terminal Configuration The back of the unit features screw terminals for wiring. A typical layout for the FCR series includes: 1. **Terminals 1-2:** Power Supply input. 2. **Terminals 3-5:** Control Output (Relay: Common, NO, NC). 3. **Terminals 7-9:** Sensor Input (A, B, B for RTD or +/- for Thermocouples). 4. **Terminals 10-12:** Alarm outputs (Event outputs). --- ### 4. Key Functions * **Auto-tuning:** The electronics automatically calculate the P (Proportional), I (Integral), and D (Derivative) constants by cycling the load. * **Sensor Burnout Protection:** If the thermocouple breaks, the electronics detect an "Upscale" or "Downscale" error and shut down the output for safety. * **Digital Filtering:** Internal software filters electronic noise from the sensor input to prevent "flickering" of the temperature reading. ---