HW_for_19-05-2021

Done by: M. Zabolotnikov group №: 9373

Homework (for the 19^th of May)

Traction motor device

A standard traction motor consists of a collector, brushes, a rotor core or armature, a main pole core, an excitation winding, and a frame. In addition, it also includes a bearing shield, a fan, and an anchor winding.

All parts are connected in several structural elements. First of all, it is a magnetic system, under the influence of which a magnetic field appears, as well as an armature with a winding that rotates with the help of bearings. The collector and other parts are separated from each other by an air layer.

In DC units, the occurrence of a magnetic field occurs with the participation of the excitation windings. They are located on the pole cores and are connected to direct current. The number of poles can be different, depending on the power of the engine and its use in the transport unit. Their number is most often in the range from 2 to 12. The standard magnetic system is a monolithic metal frame, in which there are removable charged cores.

Each traction motor is equipped with a frame, which is primarily used as a magnetic circuit, through which the magnetic flows of the main and additional poles are carried out. It also serves as a location and mounting of poles and bearing protection.

A traction electric motor running on direct current includes an excitation winding in its design, where a magneto-motive force appears, which in turn creates a magnetic field. The winding consists of coils that are put on the cores of the main poles. On the side of the core, directed to the anchor, a pole tip, also known as a shoe, is installed. With its help, the magnetic flux is evenly distributed over the entire surface of the armature. The listed parts are marked in the previous figure together with the frame.

Each traction motor with a power of more than 1 kW is equipped with additional poles, in order to reduce the number of sparks that appear on the brushes. Their device is very simple, including a core and a coil, where a copper conductor is used in isolation. Its cross-section is calculated from the operating current of the motor, since this coil and the armature winding are connected in series to each other.

The armature consists of a shaft, a core, windings and a collector. The core configuration is made in the form of a cylinder, and it is made of thin stamped sheets of electrical steel. Varnish or paper is used to insulate the sheets. In the compressed form after assembly, the core is fixed with pressure washers. Thanks to the device of the core, it is possible to compensate for the influence of eddy currents and reduce the leakage of electricity in it. Cooling of the TM is carried out due to special ventilation channels arranged in the core.