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Answer by Walter Hulshorst (dd 30-Jan-2008)
As far as I know, there is a report about this topic. Sadly I don't know who has written it and I do not know the name of the report. As far as I remember, they have researched about 150 countries and also found a relation between the installed generator capacity (MW) and the network step down transformer capacity (MVA). The relation is between 2.2 and 7.5 and can be classified into three ranges:
MVA:MW > 6
Countries having this ratio, mostly have high incomes with dense population concentration in the pacific, Europe and North America. Some are upper middle income countries amongs the richer eastern European countries. Hong Kong, Macau and several Caribbean islands also belong to this range. These are systems with well developed ring main grids serving large numbers of urban domestic consumers and a wide range of commercial and industrial consumers. The relation MVA:MW for generation system is about 2-3 and for the transmission and distribution 3-4.
MVA:MW 4 to 6
Countries within this range can be classified into several groups, ranging from those countries which have specially inadequate EHV or HV transmission as an obstacle to develop (e.g. China and India). Medium sized upper middle and lower middle income countries. And also small countries without a need for much transmission capacity.
MVA:MW < 4
These countries mostly have lower or lower middle income economies, primarily developing countries in Asia or Africa. Most basic radial networks are used.
Update October 2022
Considering the trend towards distributed generation, and the subsequent significant and increasing share of transformers for renewable power plants as well as captive power generation in industrial facilities, the above ratios merit revision. Currently, one in five transformers serves distributed generation and this ratio could become on in three over the coming decade. There are also regional differences since electricity systems are in different stages of their energy transition.
Last update: October 7, 2022