The **E5C2-R20KD** is a compact, analog temperature controller manufactured by Omron. It is widely used in industrial applications due to its simplicity, DIN rail mounting capability, and reliability for basic ON/OFF control tasks. --- ## 1. Core Technical Specifications The "R20KD" suffix defines specific electronic characteristics regarding its input type and output mechanism. | Feature | Specification | | :--- | :--- | | **Control Type** | ON/OFF or PD (Proportional-Derivative) | | **Input Type** | K-type Thermocouple (Chromel-Alumel) | | **Output Type** | Relay Contact (SPDT) | | **Supply Voltage** | 100 to 240 VAC (50/60 Hz) | | **Contact Rating** | 3A at 250 VAC (Resistive load) | | **Setting Method** | Analog Dial (Potentiometer) | | **Accuracy** | ±2% of Full Scale | --- ## 2. Key Electronic Components & Functions ### A. Input Stage (Thermocouple Interface) The unit is specifically calibrated for **K-type thermocouples**. * **Cold Junction Compensation:** Internally, the circuit compensates for the ambient temperature at the controller terminals to ensure accurate voltage-to-temperature conversion. * **High Impedance Buffer:** The input signal from a thermocouple is in millivolts (mV); the internal electronics amplify this signal for processing. ### B. Control Logic (The Comparator) Unlike digital controllers that use a microprocessor, the E5C2 often uses an **Analog Comparator IC**. * **Set Point:** Defined by the front-facing potentiometer. * **Process Value:** The actual temperature reading from the sensor. * **Hysteresis:** A built-in electronic "gap" (usually around 0.5% of the range) prevents the relay from "chattering" or switching on/off rapidly when the temperature is exactly at the set point. ### C. Output Stage (Electromechanical Relay) The "R" in the model name indicates a **Relay output**. * **Component:** An internal miniature SPDT (Single Pole Double Throw) relay. * **Operation:** When the measured temperature is below the set point, the relay energizes to activate a heater. Once the set point is reached, the relay de-energizes. ### D. Power Supply Section * **Transformer/Rectifier:** The unit converts the high-voltage AC input (100-240V) into low-voltage DC (typically 12V or 24V) to power the internal logic and the relay coil. --- ## 3. Terminal Connection Diagram The E5C2-R20KD typically uses an 8-pin circular socket (PF083A). ```text Pin 1 & 2: Power Supply (100-240 VAC) Pin 3 & 4: Relay Output (Normally Open / Common) Pin 7 (+): Thermocouple Positive (Yellow) Pin 8 (-): Thermocouple Negative (Red) ``` --- ## 4. Common Application Use-Cases * **Packaging Machines:** Controlling heat-seal bars. * **Ovens/Furnaces:** Maintaining constant temperature where complex PID tuning is not required. * **Plastic Processing:** Simple mold heating control.