Arquivos mensais: julho 2017

Factors Affecting the Life of Electric Motors

We have several factors to consider that affect the life of electric motors, such as thermal, mechanical, electrical, environmental and poor maintenance. These factors change the temperature of the engine relative to the ambient temperature, because of internal losses.

The storage of the engine is also very important and should be suitable for preserving the quality of the engine that is still in stock, unused.

There are many indications of adjustments for the enormous diversity of thermal models, because of the different factors that damage the temperature variation of an engine.

To determine the final temperature of the electric motor, the simplified thermal model will be applied, where the motor is considered a homogeneous body, and the absorbed energy is evenly supplied to the environment. At the beginning, the driven motor will have a temperature increase until reaching the thermal equilibrium, it is when it will initiate the process of heat exchange with the environment.

When developing the conjugate to drive a mechanical load coupled to its axis, the electric motor will have an increase in temperature. This temperature must not exceed the value defined by the insulation class. To determine this elevation will require the development of a thermal model.

Magnetic Core and Stator Static Winding

The magnetic core is charged with raising the magnetic flux of the field caused by the coils and thereby forming electromagnets at its poles. In direct current electric motors, these poles are fixed, as in alternating current motors the field generated is the rotating field.

The stator is designed with several thin blades of magnetic material, pressed to construct the stator assembly. The magnetic materials of the motor cores must have high saturation induction, allowing the motor to work at a high magnetic flux point, always below the saturation point.

baldor ECP3584T

The space designated for the coils is called a groove, and the structures that will constitute the poles themselves are the teeth. In the stator winding, copper coils are wound around the stator teeth, and these windings are three-phase or single-phase induction motors.

The coils are separated from each other through a varnish layer, insulated from the groove, fastened with an insulated string, and again covered with an additional layer of varnish. They are installed in such a way that the ligature of the three phases can be completed in star, triangle or other tensions.