Induction Machine: It is a machine designed in such a way that if you have two rotating magnetic fields, it normally operates as a motor and can be three-phase or single-phase (biphasic). It has starting torque, 1.5 horsepower 56c frame which in the single-phase case is achieved by special devices. No need for DC power, being robust, versatile and low cost. It is found in both large and fractional powers. As it does not use brushes, it requires little maintenance.
– Synchronous machine: It does not have starting torque, therefore it is used generally like generator, it has constant speed, for constant frequency. The excitation system, commonly mounted on the rotor, needs DC power. It can be used to correct power factor in the electrical system when operating in the over-excitation region. It is a high cost equipment and subject to periodic maintenance.
– Continuous Chain Machine: It allows great variation of speed, with very simple command. Also requires direct current source for powering the excitation circuit, which is usually mounted on the stator. It uses brushes and commutator, resulting in high construction costs and great maintenance. Operates very well as a generator or as a motor.