TYPE TEST AND TORSIONAL VIBRATION MEASUREMENT OF A GIGATOP 4-POLE GENERATOR FOR AN EPR POWER PLANT

SUMMARY The GIGATOP 4-pole turbo generators are designed for all types of half-speed turbines for nuclear power plants (NPP). For an EPR reactor, the first 1800 MW class turbogenerator designed by Alstom (OEM) is the Flamanville 3 generator. This machine is a new model, which will be the base of further derived units for future 50 Hz EPR applications or equivalent. It has been delivered after comprehensive type tests in factory, which demonstrate and validates the performances of the generator and of its future evolutions. The Flamanville 3 generator apparent power output is set at 1944 MVA, which already represents a substantial step compared to the world’s largest generators in operation in EDF nuclear fleet, the N4 units operating since the 1990s. This output has been achieved using proven technologies already used on other nuclear and fossil units. The running tests were performed for stator voltages and currents higher than the rated values, which constitute one of the worldwide largest powers ever running tested. The test stand of the OEM has been upgraded to enable an increase of the driving power by 40 %. The evaluation of the test results allows the overall performance of the machine to be checked. First heat run tests confirm that the temperature rise of the different parts of the generator are in compliance with the IEC standard criteria and also conform to calculated values. In addition to generator standard instrumentation, a large set of temporary test instrumentation was installed in order to monitor temperatures, currents, vibrations, voltages, flux density, gas velocities, etc. The temperature of neutral and short-circuit bars were monitored with a thermal camera.