Higher MVA high voltage turbine generator stator winding with multi turn coils for Global Vacuum Pressure Impregnation - Design development, engineering automation and manufacture

Multi turn coils utilizing Global Vacuum Pressure Impregnation (GVPI) technology for solid dielectric insulation of high voltage armature windings in the range of 20 to 35 MVA rating turbine generator is well established practice and number of machines are successfully operating in power sectors. This paper presents design development and manufacture of higher capacity machine in 4 pole category with multi turn diamond pulled coils to meet the power needs of industrial sectors. Design methodology, automation of engineering documentation and manufacture techniques with state of art dielectric insulation technology has been described. Technical features, dielectric requirement of higher inter turn voltages and slot fill are briefed. Experience on sample coil manufacture and test results of vacuum pressure impregnated coil are shared. Type tests result on proto type windings and performance observations have been detailed. Merits over the single transposed bar type windings are highlighted.