Why is Battery Autonomy Considered When Sizing for a UPS System?
When sizing for an Uninterruptible Power Supply (UPS) there are a number of considerations, one of which is the required battery autonomy which refers to the amount of time a UPS battery will last at a specified load level in the event of a power outage. This could be from a few minutes to a few hours with an increased autonomy being achieved by additional batteries.
Consumers are often tempted in to a false economy, opting to run a UPS at a higher load than recommended to reduce the initial cost. Not only will this have a detrimental effect on the overall efficiency of the UPS system, but it also means the UPS may not cope with a sudden inrush current. For an optimum TCO, it is recommended the autonomy requirement is based on 100% load, to protect against unforeseen spikes in mains power, but run at no more than a 50% load, ensuring high UPS efficiency and allowing for future infrastructure expansion.
Although with VRLA batteries it is possible to support loads from several minutes to several hours, the cost of a large battery at a high load level can sometimes mean that a generator is more appropriate.
For further information on how to size for a UPS system or for run time calculations, email [email protected] or call 03333 130351.