The **E5C2-R20P** is a popular analog temperature controller manufactured by Omron. It is known for its simplicity, reliability, and DIN-sized compact design. Below is a detailed breakdown of its electronic parts, specifications, and functions. --- ## 1. Core Electronic Specifications The E5C2-R20P is an ON/OFF or PD (Proportional-Derivative) control-type device. | Feature | Specification | | :--- | :--- | | **Input Type** | Platinum Resistance Thermometer (Pt100) | | **Control Output** | Relay Output (SPDT) | | **Supply Voltage** | 100 to 240 VAC (50/60 Hz) | | **Switching Capacity** | 3A at 250 VAC (Resistive load) | | **Setting Method** | Analog Dial (Potentiometer) | | **Mounting Type** | 8-pin Plug-in (Socket mount) | --- ## 2. Key Electronic Components & Functions ### A. The Input Section (Sensor Interface) The "P" in the model name signifies that this unit is designed for **Pt100 RTD (Resistance Temperature Detector)** sensors. * **Bridge Circuit:** Internally, it uses a Wheatstone bridge to detect small changes in resistance from the Pt100 sensor as temperature fluctuates. * **Compensation:** It includes circuitry to compensate for lead-wire resistance to ensure accuracy over longer distances. ### B. Control Logic (Analog Processing) Unlike modern digital controllers that use microprocessors, the E5C2 often utilizes: * **Operational Amplifiers (Op-Amps):** These compare the voltage from the setting dial (the setpoint) against the voltage from the sensor input. * **Potentiometer:** The front dial is a high-precision variable resistor used to set the desired temperature. ### C. Output Component (The Relay) The "R" in the model name stands for **Relay Output**. * **Electromagnetic Relay:** This is the mechanical switch inside the unit. When the measured temperature is below the setpoint, the relay energizes to turn on the heater. * **Contact Life:** Typically rated for 100,000 operations at full load. ### D. Indicator LEDs The front panel contains simple electronic visual indicators: * **Power LED (Green):** Indicates the unit is receiving VAC power. * **Output LED (Red):** Indicates when the relay is energized (heating is active). --- ## 3. Terminal Configuration (8-Pin Plug) The electronic interface to the outside world is handled via an 8-pin circular base: | Pin Number | Function | | :--- | :--- | | **1 & 2** | Source Power (100-240 VAC) | | **3, 4, & 5** | Relay Output (Common, NC, NO) | | **6, 7, & 8** | Pt100 Sensor Inputs | --- ## 4. Operational Circuit Summary ```mermaid graph LR A[Pt100 Sensor] --> B[Bridge/Amp Circuit] C[Dial Potentiometer] --> B B --> D[Comparator] D --> E[Relay Drive Circuit] E --> F[Heater/Load] ``` ---