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Dynamic Balancing - A Must for your Rotor

High-speed balancing (HSB) of generator and turbine rotors offers a number of advantages. These include smooth operation, access to optimal weight planes, and verification of the mechanical integrity of the rotor and any assembled components (rotors are typically run to 110% overspeed). With generators in particular, it enables electrical testing of rotors through their entire speed range. This can identify the existence of any speed related electrical faults.

Which Rotors are Good Candidates

Toshiba recommends and offers high-speed balance for problem rotors or rotors that operate above their first critical speed. Through this process, balance weights can be properly placed while taking bending mode shapes into account. Such rotor characteristics would include those that had:

  • Changes made to the centers of rotation (also known as throwing journals).
  • Generator rotors that have been completely rewound.
  • Generator rotors that have been significantly disassembled, such as removal of retaining rings and some coils.
  • Rotors that have had vibration problems produced by and/or repaired for the following:
    • Permanent bowing due to rubs or water induction
    • Loss of mass due to rubbing or other means
    • Cracking
    • Thermal Instability
  • Turbine rotors that have been re-bladed, especially if the blades were not moment weighted.
  • Turbine rotors that have had significant blade repairs.
  • Rotors that have had their journals, couplings or fits machined.

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