The **E5C4-R20J** is a classic analog temperature controller manufactured by Omron. It belongs to the E5C4 series, which is known for its compact size (DIN 48x48) and simple rotary dial operation. Below is a detailed breakdown of its electronic components, specifications, and wiring structure. --- ## 1. Technical Specifications This model is characterized by its input type and output relay mechanism. | Feature | Specification | | :--- | :--- | | **Model Type** | Analog Temperature Controller | | **Input Type** | J-Type Thermocouple (Iron-Constantan) | | **Control Mode** | ON/OFF or Proportional (P) Control | | **Output Type** | Relay Output (SPDT) | | **Supply Voltage** | 100/110/120 VAC or 200/220/240 VAC (50/60 Hz) | | **Setting Method** | Analog Dial (Potentiometer) | | **Mounting** | 8-pin round socket (Plug-in) | --- ## 2. Key Electronic Components ### A. The Control Circuit The internal logic uses a comparator circuit. It compares the millivolt (mV) signal generated by the **J-type thermocouple** against a reference voltage set by the front-panel potentiometer. * **Cold Junction Compensation:** Integrated circuitry compensates for the ambient temperature at the controller terminals to ensure accurate thermocouple readings. ### B. Output Relay The "R" in the model name signifies a **Relay Output**. * **Rating:** Typically 3A at 250 VAC. * **Function:** It acts as a mechanical switch to turn a heater or contactor on and off. Since it is a physical relay, it has a finite life cycle (approx. 100,000 operations). ### C. Input Interface (J-Type) The "J" in the model suffix indicates it is specifically calibrated for **J-type thermocouples**. * **Polarity Sensitive:** Pin connections must be correct (Positive/Negative) to prevent the temperature reading from moving in the opposite direction. --- ## 3. Terminal Configuration (8-Pin Socket) The E5C4-R20J uses a standard 8-pin circular base. The internal electronic connections are generally mapped as follows: | Pin Number | Function | | :--- | :--- | | **1 & 2** | Source Power (VAC) | | **3, 4, 5** | Relay Output (Common, NO, NC) | | **7 (+)** | Thermocouple Input (Positive) | | **8 (-)** | Thermocouple Input (Negative) | --- ## 4. Operation Indicators The unit features two primary LED indicators on the faceplate: 1. **PW (Power):** Green LED indicating the unit is energized. 2. **OUT (Output):** Red LED indicating the relay is currently energized (heating is active). --- ## 5. Typical Application Circuit ```mermaid graph LR A[Power Source] --> B[E5C4-R20J] C[J-Type Thermocouple] --> B B --> D[Magnetic Contactor] D --> E[Electric Heater] ```