The currents absorbed by the motor with double rotor casing during operation expressed by means of parameters to be determined experimentally

The course of the currents absorbed by an asynchronous motor with double rotor casing during the electromagnetic transient phases under operational conditions was determined analytically. To speed up the analytical process the equivalent biaxial machine with straight axis was considered, containing two sets of windings on the stator and four on the rotor, two being equivalent to the external casing and two to the internal one. The differential equations of the electromagnetic equilibrium, containing the parameters of the machine and the angular velocity, are resolved by operational calculus. The number is reduced from 6 to 3 introducing complex numbers relative to the power supply, stator current, and currents in the casings. This permits the graphical determination of the currents absorbed by the machine through the space described by the vector representing the complex number relative to the stator currents. The theoretical results were compared with the experimental ones with optimal results.