Vibration problems in the design of the 95 MVA motor-generator set for the 28 GeV proton synchrotron at CERN

The main ring magnets of the 28 GeV proton synchrotron at CERN are pulse-excited from a motor generator. Power peaks of up to 70 MW cause torque shocks in the generator up to a maximum of 1 MNm (100 tonne m). The resulting vibrations must not be allowed to reach the ring magnets. The design of the machines presented a number of interesting dynamic problems. Two of the most important were the vibration of the flexibly supported foundation and the torsional vibration between the motor and generator which occurs when running on pulse duty and in the case of motor or generator line-to-line short-circuits. Measurements taken during commissioning showed that the operating performance was fully satisfactory and confirmed the design calculations. (4 refs).