If your spindle application calls for moderate speed regulation, and will operate at one
or two defined speeds, then a standard ac motor may be a candidate. Speed regulation would
be limited to the slip of the motor, approximately 1.5 to 3% of base speed. Some applications
use a one or two-speed motor with or without a changeable-ratio gear box.
However, for a high-performance adjustable- speed operation, a vector controller with an ac
spindle motor should be used.