The 2400W AC-input power shelf includes three 1200-watt (W) AC-input power modules that plug into a common power backplane in the 2400W AC-input power shelf. Two 1200W AC-input power modules are capable of powering a fully configured Cisco AS5850 server. The third power module provides full redundancy.During normal operation, the three AC-input power modules provide automatic load-sharing, with each power module supporting 33 percent of the power load. When you remove one of the AC-input power modules, the remaining power modules immediately ramp up to full power and maintain uninterrupted system power.The AC-input power modules in the 2400W AC-input power shelf are hot-swappable, allowing you to remove or replace a power module while the system is operating; system operation will not be affected.Each AC-input power module is powered on automatically when it is plugged in and receiving power. Ejector lever/handles secure each power module to the backplane connectors and allow you to remove and replace the power modules with ease.The 2400W AC-input power shelf is two rack units high (3.5 in. [8.88 cm]) and mounts underneath the server in a standard 19-inch 4-post or telco-type rack assembly.All cable connections for AC-input power, DC-output power, and status signals are made from the 2400W AC-input power shelf rear. Three modular power cables connect each AC-input power module to the site AC-input power source. Two DC-interconnect cables provide DC-output power to the server. Two monitor cables provide a status signal connection to the PEM maintenance bus (Mbus), which monitors voltage tolerance levels, temperature conditions, and power failure in the enhanced AC-input power shelf. A grounding cable provides a ground connection from the 2400W AC-input power shelf to the server.AC power modules installed in the enhanced AC-input power shelf are protected against overcurrent by circuit breakers, and against overtemperature by internal protection circuits.A spring-clip locking mechanism in the ejector lever/handles holds individual AC power modules in place, and prevents the power module from vibrating or sliding out of the power bay and dislodging from the power backplane. A small flat-blade screwdriver is needed to delatch the AC modules. Pulling on the handles without properly releasing the latches can damage the modules.Double grounding lugs (as per NEBS requirements) on both the enhanced AC-input power shelf and the server provide electrical grounding.The power modules are self-monitoring. Each power module monitors its own temperature and internal voltages. An internal fan in each power module draws cooling air from the front of the power shelf, through the power module, and out the rear of the power shelf. The power module airflow is separate from the rest of the Cisco AS5850 components.Internal monitoring data is passed to the server through the maintenance bus (Mbus) monitoring system. You can view this data through a terminal connected to the RSC console port.