The **PWR-3K-AC-R** is a high-capacity, hot-swappable AC power supply module designed primarily for the **Cisco Nexus 9500 Series** modular switches. The "R" in the part number indicates **Back-to-Front (Port-Side Intake)** airflow, typically used in specific data center rack configurations. --- ### ## Technical Specifications Below are the primary electronic and physical characteristics of the module: | Feature | Specification | | :--- | :--- | | **Input Voltage** | 200V to 240V AC (Nominal) | | **Output Wattage** | 3000 Watts | | **Input Frequency** | 50 to 60 Hz | | **Efficiency** | 80 Plus Platinum Certified (approx. 94% efficiency) | | **Airflow Direction** | Back-to-Front (Red handle color coding) | | **Connector Type** | C19/C20 High-current inlet | | **Redundancy** | N+1 and N+N supported | --- ### ### Key Electronic Components & Functions 1. **Power Factor Correction (PFC):** The unit utilizes active PFC circuits to ensure that the input current waveform is in phase with the voltage waveform, minimizing reactive power loss and harmonics in the data center power grid. 2. **DC-DC Conversion Stage:** The module converts high-voltage AC input into the +12V DC main bus voltage required by the Nexus chassis backplane. High-frequency switching transistors (MOSFETs) are used to maintain high efficiency and compact size. 3. **Internal Microcontroller (I2C/SMBus):** The power supply features an integrated management chip that communicates with the Cisco NX-OS via the I2C protocol. This allows the system to monitor: * **Inlet/Outlet temperatures.** * **Real-time power consumption (Watts).** * **Voltage and Amperage levels.** * **Fan health and RPM.** 4. **Protection Circuitry:** * **Over-Voltage Protection (OVP):** Shuts down the unit if output voltage exceeds safety thresholds. * **Over-Current Protection (OCP):** Prevents damage during short circuits. * **Over-Temperature Protection (OTP):** Throttles or shuts down if internal components overheat. --- ### ### Compatibility and Airflow It is critical to match the airflow direction of the power supply with the fan trays of the chassis. * **PWR-3K-AC-R:** Red color-coded handle. Air is pulled from the power supply side and exhausted toward the port side (Back-to-Front). * **PWR-3K-AC-B:** Blue color-coded handle. Air is pulled from the port side and exhausted toward the power supply side (Front-to-Back). ---