5.3　Voltage Level

5.3.1　The configuration of voltage level of urban distribution networks shall comply with the current national standard GB/T 156 Standard Voltage.Voltage levels of 110kV，66kV and 35kV may be used for HV distribution networks；10kV and 20kV for MV distribution networks；220V and 380V for LV distribution networks.With urban load increasing，MV distribution networks may be upgraded to 35kV while HV distribution networks to 220kV or 330kV.

5.3.2　No more than three transformations of voltage should be used for urban distribution networks.