There are a number of facilities where a UPS is not necessary or cannot provide the reliability or robustness needed, but where voltage regulation and the attenuation of dangerous voltages is still critical to the reliable operation of the plant. Static Power produces a number of static power regulators with transient protection incorporated, which typically consists of a transformer based buck/boost regulator. These units are used for installation applications to provide almost step-free transparent control of the output voltage, attenuation of harmful impulses or surges and other power line disturbances. They provide protection and regulated power process equipment but without back-up. Sizes range from single phase 50 Amperes to three phase 500 Amperes from nominal low voltage (230/400) to 22kV.