Two-Stage Rototrol for Low-Energy Regulating Systems

The fundamental principles of operation and application of Rototrols have been discussed in a number of papers and publications. These have dealt with a unit having only one stage of amplification of the control energy. Such machines have been applied widely during the last 15 years with excellent results. Recently a few applications have arisen in which the control energy available was too small to provide satisfactory regulation. The use of a second unit operating as a control energy amplifier was then needed. The development of the 2-stage Rototrol permits the use of only one machine in such applications. The simplest construction of this machine is a 4-pole design. It is a normal generator except for the field coils and armature connections. With such modifications this paper shows that the machine may be considered as three generators superimposed on one another. The output of only two of these is used in the machine under consideration. The analysis of operation and means of compensation for the resulting reactions are given. Tests of two designs show that high sensitivity and speed of response were obtained. It is concluded that the development of this machine provided a generating element for Rototrol systems which requires an extremely low value of control energy.