Ferroresonant servomotor

The operating principle of the ferroresonant servomotor is described. It is shown that this new actuator for automatic systems is also an amplifier which can be controlled directly by transducers with low-power d.c. signals (photodiodes etc.), so that amplifiers and d.c.-a.c. convertors are eliminated. A comparison is made with the amplifier servomotor, described in a previous paper, showing that the ferroresonant servomotor is much simpler and cheaper. The running régime is analysed, establishing expressions for rotor current, m.m.f., flux and torque. Theoretical curves are compared with experimental results. An automatic control system without relays and amplifiers, having a ferroresonant servomotor as actuator, is also described.