1. Field of the Invention
The present invention relates to power supply apparatus and methods of operation thereof, and more particularly, to uninterruptible power supplies (UPSs) and methods of operation thereof.
2. Description of Background
UPSs are commonly used to provide conditioned and/or auxiliary power to electronic equipment that provides critical functions, such as computer systems, telecommunications systems and medical equipment. Typically, UPSs can provide AC power from a backup source, such as a battery, generator or fuel cell, in the event that a utility power supply fails or becomes degraded.
A single UPS may be used to provide backup power to a large number of devices, for example, servers, monitors, coffee makers, refrigerators and the like. When the utility power is lost or becomes degraded, the UPS may provide power to all of these devices from the backup source. Conventional UPSs may include one or more load segments, i.e., groups of receptacles that can be independently controlled. Typically, power can only be removed from devices being powered by the UPS by turning off the UPS or by removing power from all of the devices plugged into a load segment. Furthermore, to conserve the amount of power used from the backup power source, devices, such as computers or servers, may be placed in a standby mode during a power loss. For example, operating systems running on servers may enter a reduced power state, but some power will still be supplied to the servers from the backup source. Thus, the devices in standby mode may still be drawing some power from the backup source. Furthermore, once the primary power source is restored, each of the devices placed in standby mode may have to be awakened manually before service can be fully restored. This can be quite time consuming if the UPS is used to provide power to an entire office building housing hundreds of servers, all of which were put in standby mode during the power loss.
Currently, pieces of information technology equipment (ITE) or data center infrastructure equipment (DCIE) are able to communicate with multiple UPSs. However, the communication between the ITE or DCIE and the UPSs implement an OR condition rather than an AND condition. The OR condition means the ITE or DCIE is notified if one UPS signals a condition and reacts to it regardless of the status on the second UPS. What is needed is a system that allows the ITE or DCIE to communicate with two UPSs and requires both UPSs to signal a condition before alerting the ITE or DCIE.