Test results of the world´s largest four-pole generators with water-cooled stator and rotor windings

Two turbogenerators, the largest ever produced with direct water-cooling of both rotor and stator windings, were completed and tested early in 1974. Their losses and efficiency from test, together with temperatures in critical areas and cooling circuit behavior are described. Vibration of coil ends was measured at rated voltage and during sudden short circuit using a newly perfected photo cell technique. Based on the test results, it is estimated that generators can now be built in ratings up to 2400 MVA at 1800 rpm using presently available rotor forgings with water-cooled windings.