dc motor and generator pdf

Dc motor and generator pdf

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Published: 16.11.2020

DC motors as Generators

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What is a DC Generator : Construction and Its Working

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DC motors as Generators

The initial electromagnetic generator Faraday disk was invented by British scientist namely Michael Faraday in the year A DC generator is an electrical device used for generating electrical energy. The main function of this device is to change mechanical energy into electrical energy. There are several types of mechanical energy sources available such as hand cranks, internal combustion engines, water turbines, gas and steam turbines. The generator provides power to all the electrical power grids.

The reverse function of the generator can be done by an electric motor. The main function of the motor is to convert electrical energy to mechanical. Motors, as well as generators, have similar features. This article discusses an overview of DC generators. A DC generator or direct current generator is one kind of electrical machine, and the main function of this machine is to convert mechanical energy into DC direct current electricity.

The energy alteration process uses the principle of energetically induced electromotive force. This electromotive force can cause a flow of current when the conductor circuit is not opened. A DC generator is also used as a DC motor without changing its construction. The construction of a 4-pole DC generator is shown below.

But the two essential parts of this device are the stator as well as the rotor. The stator is an essential part of the DC generator, and the main function of this is to provide the magnetic fields where the coils spin.

This includes stable magnets, where two of them are with reverse poles facing. These magnets are located to fit in the region of the rotor. Rotor or armature core is the second essential part of the DC generator, and it includes slotted iron laminations with slots that are stacked to shape a cylindrical armature core. Generally, these laminations are offered to decrease the loss because of the eddy current.

The armature core slots are mainly used for holding the armature windings. These are in a closed circuit winding form, and it is connected in series to parallel for enhancing the sum of produced current. The external structure of the DC generator is Yoke, and it is made with cast iron otherwise steel. It gives the necessary mechanical power for carrying the magnetic-flux given through the poles. These are mainly used to hold the field windings.

In addition, the poles will give joint toward the yoke with the welding method otherwise by using screws. The pole shoe is mainly utilized for spreading the magnetic flux as well as to avoid the field coil from falling.

The working of the commutator is like a rectifier for changing AC voltage to the DC voltage within the armature winding to across the brushes. It is designed with a copper segment, and each copper segment is protected from each other with the help of mica sheets. It is located on the shaft of the machine.

The main function of the commutator in the dc generator is to change the AC to DC. It acts like a reversing switch and its role in the generator is discussed below. The emf which is induced within the armature coil of the generator is alternating.

So, the flow of current within the armature coil can also be alternating current. This current can be reversed through the commutator at the accurate moment once the armature coil crosses the magnetic unbiased axis. Thus, the load attains a DC or uni-directional current. The commutator guarantees that the flow of current from the generator will flow forever in a single direction.

The electrical connections can be ensured between the commutator as well as the exterior load circuit with the help of brushes. When a conductor is located in an unstable magnetic field, an electromotive force gets induced within the conductor.

The induced e. If the conductor is present with a closed lane, the current which is induced will flow in the lane. In this generator, field coils will generate an electromagnetic field as well as the armature conductors are turned into the field. Therefore, an electromagnetically induced electromotive force e. The classification of DC generators can be done in two most important categories namely separately excited as well as self-excited.

In separately excited type, the field coils are strengthened from an autonomous exterior DC source. In the self-excited type, the field coils are strengthened from the generated current with the generator. The generation of the first electromotive force will occur because of its outstanding magnetism within field poles. The produced electromotive force will cause a fraction of current to supply in the field coils, therefore which will increase the field flux as well as electromotive force generation.

Further, these types of dc generators can be classified into three types namely series wound, shunt-wound, and compound wound.

There are different kinds of machines available in the market where the total input energy cannot be changed into output due to the loss in the input energy. So different losses can occur in this type of generator.

For generators like shunt-wound, the field copper loss is equivalent to Ish2Rsh which is almost stable. For generators like a series wound, the field copper loss is equivalent to Ise2 Rse which is also almost stable. For generators like compound-wound, the filed copper loss is similar to Icomp2 Rcomp which is also nearly stable.

This loss mainly occurs because of the reversal of the armature core. Whenever the core supplies below one set of poles, then the core will finish one series of frequency reversal. This huge current is known as eddy current whereas the loss is called the eddy current loss. Stray losses mainly occur by combining the losses like core as well as mechanical. These losses are also called rotational losses.

Generally, generators are classified into two types like AC and DC. The main function of these generators is to change the power from mechanical to electrical. An AC generator generates an alternating current whereas the DC generator generates direct power. This law tells that once a conductor shifts within a magnetic field then it slashes magnetic lines of force to stimulate an EMF or electromagnetic force within the conductor.

Once the circuit of the conductor is closed then the emf can cause flow of current. These differences can assist students to study about this topic but before that, one should know about the AC generators as well as dc generators in every detail so that differences are very simple to understand. The characteristic of the DC generator can be defined as the graphical representation among the two separate quantities.

The most essential characteristics of this generator are discussed below. The magnetization characteristics provide the difference of producing voltage otherwise no-load voltage through field current at a stable speed.

This kind of characteristic is also known as an open circuit otherwise no-load characteristic. The load or external type characteristics provide the main relationships among the load current as well as terminal voltage at a stable speed. The applications of different types of DC generators include the following. Thus, this is all about the DC generator. Here is a question for you, what are the disadvantages of DC generators? What is a DC Generator?

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These are the pole structures generally smaller than main poles and is placed in between the main poles. These windings of the inter poles are of less turns since it is connected in series with armature windings. The main purpose of these inter poles is to reduce the armature reaction, thereby reducing the sparks at the brush contacts. The polarity of the inter pole is made same as that of the main pole ahead of it in the direction of rotation. The rotor is generally rotating part which carries the armature, armature windings and the commutator on the same shaft. The armature core is made of laminated silicon steel.

A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine. Two or more electrical contacts called " brushes " made of a soft conductive material like carbon press against the commutator, making sliding contact with successive segments of the commutator as it rotates. The windings coils of wire on the armature are connected to the commutator segments. Commutators are used in direct current DC machines: dynamos DC generators and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force torque is produced.

What is a DC Generator : Construction and Its Working

In the present day world, electrical energy is generated in bulk in the form of an alternating current. Hence, the use of DC machines, i. They are mainly used in supplying excitation of small and medium-range alternators. Nowadays, the alternating current is generated first and then it is converted into DC by the rectifiers.

A dc generator is an electrical machine which converts mechanical energy into direct current electricity. This energy conversion is based on the principle of production of dynamically induced emf. This article outlines basic construction and working of a DC generator. Note: Theoretically, a DC generator can be used as a DC motor without any constructional changes and vice versa is also possible.

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DC motors as Generators

Дэвид смотрел на нее и улыбался. - Ну и что ты скажешь, моя красавица. Выйдешь за меня замуж. Лежа в кровати с балдахином, она смотрела на него и знала, что ей нужен именно. Навсегда. Ее завораживала глубина его темно-зеленых глаз, и она не могла отвести от них взгляд. В этот момент где-то вдали раздался оглушительный колокольный звон.

Беккер поблагодарил. Отпил глоток и чуть не поперхнулся. Ничего себе капелька. В голове у нее стучало. Повернувшись, она увидела, как за стеной, в шифровалке, Чатрукьян что-то говорит Хейлу.

Он тихо выругался. Тогда почему они послали не профессионального агента, а университетского преподавателя. Выйдя из зоны видимости бармена, Беккер вылил остатки напитка в цветочный горшок. От водки у него появилось легкое головокружение. Сьюзан, подшучивая над ним, часто говорила, что напоить его не составляет никакого труда.

5 comments

  • Creissant B. 17.11.2020 at 20:49

    DC Motor/Generator module to demonstrate and explain the operation of dc motors and generators. Operating principle of dc motors. As stated in Unit 1, motors.

    Reply
  • Hossana P. 20.11.2020 at 10:36

    The initial electromagnetic generator Faraday disk was invented by British scientist namely Michael Faraday in the year

    Reply
  • Bailey F. 25.11.2020 at 03:55

    Explain the effect of motor reaction in a dc generator. Explain the causes of armature losses. List the types of armatures used in dc generators. State.

    Reply
  • Audomaro V. 25.11.2020 at 07:32

    To browse Academia.

    Reply
  • Desire C. 25.11.2020 at 16:54

    Since our motors are very efficient, this is also true when operated as generators.

    Reply

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