An on-line control system is developed to achieve the rigid rotor balancing during operation. The system consists of a shell shaped moving mass supported by lief springs which are mounted on the rotor disc, four magnets mounted on the rotor disc to position the floating mass, two proximity sensors located perpendicular to each other at the mid span of the shaft, a d.c. motor with a universal joint type of coupling, a slip ring assembly, and a microcomputer.
Experimental works are performed to evaluate the performance of the balancing system when the unbalance masses are introduced purposely. The speed range for the experiments is chosen such that the synchronous shaft vibration to rotational speed dominates.
It is found that the balancing system has a good balancing effect at the speed range of 1000-1300 rpm, with up to 129.2 g-mm unbalance.