There are two ways to effectively reduce the voltage at the start, the first is supplying current at normal voltage, forcing the motor to connect in the network with the winding to a higher voltage, thus using the star-delta starting system. The second way is to supply current under voltage, by means of resistors, inductors or autotransformer.
All low voltage starting systems have drawbacks as the starting torque or torque reduces according to the square of the voltage reduction supplied to the motor. The electric motors of direct current, the speed must be regulated by the insertion of a rheostat in the field circuit, to provide adjustments in the flow.
The link between motors 1125-4-200-EA and a public power grid must follow specific requirements for this purpose, determined by standards. In most cases, it is necessary to remove a motor at full voltage in order to take full advantage of the starting torque. When starting the full voltage of an electric motor causes a voltage drop higher than the maximum permissible, it is important that a specific starting device with reduced voltage is used.
The transformer is one of the electrical devices with numerous possibilities of application and use. One of the factors that contributes to this great versatility is that it allows the precise adjustment of the voltages, as well as the currents, according to the existing needs. In this way, if one takes into account the process of supplying electric energy, it is easily possible to conclude that, due to the large number of applications, consequently, the power required also has to be greater.
It is also necessary to consider that the sources of production need to remain concentrated, resulting in significant economies of scale, as in the case of greater distances between the production of electricity and its consumption, for example. Thus, it can be concluded that a large electric power is able to transport for a greater distance, being able to cause some high Joule losses. For example, in the case of a hydroelectric plant that has a 300 MVA generator at 60 kV, the electric power generated will be capable of supplying a city on average 50 km away by means of a cable with resistance of 0.2 W / Km.
Transformers operate according to Faraday’s law or the first law of Electromagnetism ¨ An electric current is induced in a circuit if it is under the action of a variable magnetic field¨.
A magnetic field is a region of space induced by any moving charge, such as the electric current (i) corresponding to moving electrons, or by material with specific properties, such as the magnet.
The electric charge acme TB81301 creates around itself an electric field with lines of electric field entering (negative charge) or leaving (positive charge). The magnet and a moving charge create a magnetic field (B), and whenever its field lines arise from a north pole (positive) and arrives at a south pole (negative), thus unraveling two poles simultaneously.
The earth also has this same principle, it generates a magnetic field due to its nucleus formed by iron and nickel, thus possessing north and south poles, and this is inclusive, the principle of operation of the compass, used for localization, and is a magnet With its north always pointing towards geographical land north.