What is Eco Mode UPS operation?

In a datacentre environment, Eco mode can be used to improve the operating efficiency of the uninterruptible power supply. Eco mode can raise the efficiency of the UPS to 99% and is a line interactive type mode of operation only recommended for installations with secure and stable electrical power supplies. Some UPS can be set to operate in an auto-select mode that allows the firmware to make the decision of whether to operate in full on-line or eco mode depending upon the condition of the mains power supply.