From October 17 to December 16, 2023, the National Energy Foundation and Management Standardization Technical Committee (SAC/TC20) is seeking opinions on the mandatory national standard "GB 20052 Minimum allowable values of energy efficiency and the energy efficiency grades for power transformers (Draft for Comments)."

This standard aims to replace its 2020 version. Compared to the previous version, the main technical changes include:

l  The scope of application has been expanded to include "three-phase oil-immersed transformers and dry-type transformers for the new energy generation side (photovoltaics, wind, and energy storage), with voltage levels of 6kV, 10kV, 35kV, and 66kV, no-excitation voltage regulation, rated frequency of 50Hz, and rated capacity ranging from 500kVA to 63000kVA." The scope no longer includes "high-impedance transformers."

l  Minimum allowable values of energy efficiency of 6kV, 10kV, 35kV, and 66kV new energy generation side (for photovoltaic, wind, and energy storage) transformers have been added.

l  Minimum allowable values of energy efficiency of 6kV, 10kV, 35kV, and 66kV oil-immersed and dry-type three-phase dual-winding no-excitation-voltage-regulation new energy generation side (for photovoltaic, wind, and energy storage) transformers (6~7.2kV/0.4~1.14kV) have been added.

l  Minimum allowable load loss values for 10kV 2500kVA oil-immersed three-phase dual-winding distribution transformers without excitation-voltage regulation, pertaining to energy efficiency grades 1 and 2 have been revised.

l  The short-circuit impedance of some 10kV dry-type three-phase dual-winding no-excitation-voltage-regulation distribution transformers has been modified.

l  The short-circuit impedance of some 66kV and 110KV oil-immersed three-phase dual-winding on-load voltage-adjustable power transformers has been modified.