A new type of magnetic servo amplifier

IN REFERRING to the damping properties of 2-phase induction motors which are extensively used in high-performance servomechanisms, it is important to stress that some of these motors have good viscous friction to inertia ratios or special damping means, and others have not. Separately excited induction-meter-type reversible motors, as sometimes used in self-balancing potentiometer recorders, have a permanent magnet producing eddy-current damping. Some types of low-inertia squirrel-cage induction motors and drag-cup-type motors have eddy-current damping devices built into the motor. There are, however, other constructions of such motors which have virtually no damping properties so that additional damping methods must be applied to prevent hunting.