Dear IWP&DC, The new design by ABB of a hydro machine generating at 40kV which dispenses with the need for a step-up output transformer is most innovative, but it is not the world’s first high voltage generator as suggested in the article in the April issue of IWP&DC (pp34&35).

In the UK in the 1920s and 1930s turbo alternators were in service with terminal voltages of 33kV supplied directly to the grid. Presumably the increases in transmission voltages in the UK nullified these advantages.

I also saw an article in the 1970s (Electrical Times, 14 January 1977) reporting the successful testing of a hydro generator at the Skodnya power station outside Moscow which generated at 100kV, with further plans for a 165kV machine. The reported benefits again were the elimination of an output transformer.

I have never seen any further reference to these machines so possibly they were not a success in the longer term.