5. Balancing flexible rotors

The quest for excellent vibration behavior of machines on site leads to balancing as close as possible to operating conditions, i.e. :

• higher out-of-balance excitations at high speeds, resulting in improved sensitivity;

• often supercritical operation, with flexible rather than rigid rotor balancing techniques;

• higher drive power, requiring special balancing systems;

• throws over the entire speed range to cover low-speed operation (start-up), critical speeds and the normal range of continuous operation.

These techniques also cover in-situ balancing, the most complex case of which is that of the shaft lines of large turboalternator sets in power generation plants (alternator driven by a turbine comprising a...