Power limiting system and method in a multiple power source environment

Abstract

A power limiting system and method are provided for limiting power delivered to a common bus in a one or multi-frame tape library environment. The system includes one or more frames coupled to a common bus, each of which is capable of delivering power to the common bus. Each frame comprises current limiting circuitry to limit the power delivered by that frame to the common bus. In exemplary embodiments, the current limiting circuitry of each frame includes a current limiting resistor and a blocking diode coupled to a local power source to limit the power delivered by that frame and to prevent feedback respectively. Additionally, each frame of the system includes a relay capable of receiving a limited power from the common bus, being energized, and, consequently, providing for the respective frame to be powered by a main power supply. In exemplary embodiments, each frame includes a switch for taking power from the common bus to power a frame only when a respective local power source is on and a respective frame is energized. The method provided includes a method for coupling additional frames to a power limited common bus by limiting the power delivered by each frame. Specifically, the method provides for only those frames, which are delivering power to the common bus, to be powered by the power available on the common bus.