In the motors the coils are made with bare copper bars. A coil winding is made by two parts, which are welded together on the coil head. The insulation of the coils is generally done by coating with “stage B” (catalyzed) mica-based tapes, the same process being the stator. The coils are rigidly affixed within the grooves through wedges. The collector rings are made of stainless steel (standard), however they can be fitted in brass or brass, depending on the application and where they will be installed.
The rotor is short-circuited by intercession 1115-000-001 of the collector rings and brushes, which give access to the rotor winding, these are designed to tolerate the required maximum operating current and the heat dissipation generated by the electric current and the contact between brushes and rings. Through the brushes and the collector it is possible to connect a three-phase resistor in series with the rotor windings, thus modifying the secondary impedance of the motor. With a rheostat in series with the rotor it is permissible to regulate the current and the starting torque or in the regime conditions to vary the working rotation by means of the variation of the slip.