This IEC standard applies to medium power transformers from 25 kVA up to 3150 kVA with highest voltage for equipment up to 36 kV or low voltage networks with highest voltage for equipment of 1,1 kV equipped with voltage regulating devices. Voltage Regulating Distribution Transformers are transformers equipped with components to control primary or secondary voltage for on load voltage regulation purposes. The main objective of the installation of a VRDT is to regulate the LV network voltage level (i.e.400 V), to avoid violation of the limits defined by relevant standards or regulations. The VRDT has to operate properly as a step down and step up transformer. Transformers covered by this standard comply with the relevant requirements prescribed in the IEC 60076 standards and for Europe EN 50160 and EN 50588-1 unless otherwise stated in this standard.