## Technical Analysis: PR2-RSC3-LV-120AC Relay Module The **PR2-RSC3-LV-120AC** is a pre-assembled relay module manufactured by **Phoenix Contact**. It is part of the PR2 series, designed for industrial automation to interface between control controllers (PLCs) and field loads. ### 1. Component Overview This part is a complete assembly consisting of four primary sub-components: | Component | Description | Function | | :--- | :--- | :--- | | **Relay Base** | PR2-BSC3/4X21 | The socket that mounts to the DIN rail and provides wiring terminals. | | **Plug-in Relay** | REL-IR2/L-120AC | The actual electromechanical switching element. | | **Indicator/Suppression Module** | V-120-230UC | A plug-in module providing status LEDs and surge protection. | | **Retaining Bracket** | EL2-P35 | A plastic clip that locks the relay into the base. | --- ### 2. Electrical Specifications The internal electronics are optimized for 120V AC control systems. #### A. Input (Coil Side) * **Nominal Input Voltage:** 120 V AC * **Typical Input Current:** ~9 mA (at 60 Hz) * **Operating Indicator:** Integrated yellow LED. * **Protection Circuit:** Varistor (protects against voltage spikes when the coil is de-energized). #### B. Output (Contact Side) * **Contact Type:** 2 PDT (Double Pole, Double Throw / 2 Changeover contacts). * **Contact Material:** AgNi (Silver-Nickel), common for general-purpose switching. * **Maximum Switching Voltage:** 250 V AC/DC. * **Limiting Continuous Current:** 10 A per contact. * **Minimum Switching Capacity:** 12 V, 10 mA. --- ### 3. Connection and Wiring The unit uses **Screw Connections (RSC)**. | Terminal Label | Function | Type | | :--- | :--- | :--- | | **A1 / A2** | Coil Input | 120V AC Power | | **11 / 21** | Common (COM) | Input power for the load | | **12 / 22** | Normally Closed (NC) | Output (Conducts when relay is OFF) | | **14 / 24** | Normally Open (NO) | Output (Conducts when relay is ON) | --- ### 4. Key Electronic Features 1. **Mechanical Intervention:** The relay usually includes a manual test button (often orange for AC units) to toggle the contacts without power for troubleshooting. 2. **Galvanic Isolation:** Provides safe separation between the low-power control side (PLC) and the high-power load side. 3. **Modular Design:** If the contacts wear out, the REL-IR2 plug-in relay can be replaced without disconnecting the field wiring from the base. ---