Experimental Investigation Of Balancing Flexible Rotors In Large Motors And Generators

Abstract

The balancing of large motor and generator rotors is accomplished by a combination of balance machine corrections plus the calculated corrections determined by an Influence Coefficient Balancing computer program. The method has been applied to an 8000 HP two-pole induction machine rotor and the results are presented. The vibration is measured at several locations and speeds and the results are used to (a) ensure that the vibration levels are not excessive as the rotor speed is increased and (b) calculate the balance correction weights using a least squares Influence Coefficient Method. Measured and calculated results are presented which provide a check on the method. The results show that a multi-plane balance correction was necessary to minimize the rotor unbalance through the second critical speed.