Improved Cooling for Generators of Large Rating

Improved ventilation, through the increase in the mass flow of hydrogen in both rotor conductors and stator vents, has permitted increases in turbine-generator ratings. Further advances in ventilation, and thus in rating, are obtained 1) by paralleling the cooling paths in the rotor by means of zoning which employs the full fan pressure and 2) by using higher capacity gas-cooled stator coils with two sets of vent ducts per conductor with bare end connectors. Further increased stator ratings are obtained by introducing higher pressure (or higher mass flow) hydrogen to the stator coils through connectors and an external pumping system. With hydrogen cooling, substantial increases in machine ratings are now possible, within practical frame sizes and with high efficiencies, to match ratings of present-day large tandem compound turbines.