: Standard values include 750 V, 1,500 V, and 3,000 V.
66 kV, 110 kV, 132 kV, 220 kV, 400 kV, and higher. iec 60038 standard voltages pdf 103
: Transmission, distribution, and utilization systems above 100 V at 50 Hz and 60 Hz. : Standard values include 750 V, 1,500 V, and 3,000 V
Under normal conditions, the supply voltage should not vary by more than ±10% from the nominal value . : Standard values include 750 V
Mass production of standardized components (like transformers, switchgear, and motors) lowers manufacturing costs through economies of scale.
The you need to cross-reference