Emerson has announced the new Series D update to the family of proven SolaHD industrial rack mount on-line uninterruptible power supplies (UPSs). The new SolaHD S4KD Series replaces the current S4KC Series, offering significant user interface improvements and other design upgrades to increase reliability and product availability. The S4KD is an on-line (double conversion) UPS, providing a zero-transfer time from external to internal power upon utility power failure to deliver a seamless flow of power for critical loads. The S4KD is available in 1000-3000 VA in 120 V and 3000 VA in 230 V configurations, each housed in a slim 2U form factor.