The significance of conductivity and polarization in materials for electrostatic motors

An electrostatic motor has been designed and built, and its construction is described. It was capable of running either as an induction motor or as a synchronous motor, depending on the electrical characteristics of the rotor material. The critical factor determining which behaviour is exhibited appears to be the time constant of the rotor material. Analytical expressions are given for the mechanical torque developed when the machine is running in each mode. When mechanical torque was applied to the axle of the unenergised machine, it was observed that an ac emf appeared at the terminals and the machine was therefore operating as a generator.