comutador

What are São comutadores?

São comutadores tradicionais, que funcionam como pontes de várias portas. Seu principal objetivo é dividir uma LAN em vários domínios de colisão ou, no caso de redes em anel, segmentar a LAN em diferentes anéis. Eles baseiam sua decisão de envio no endereço MAC de destino que cada quadro contém.

What is a conmutador and what is it for?

En una instalación eléctrica, un conmutador es un dispositivo eléctrico o electrónico que permite modificar el camino que deben seguir los electrones. Son típicos los manuales, como los utilizados en las viviendas y en dispositivos eléctricos, y los que poseen algunos componentes eléctricos o electrónicos como el relé.

What is the difference between Terminal Común and conmutador?

El terminal común puede cambiar entre los terminales L1 y L2. En una instalación eléctrica, un conmutador es un dispositivo eléctrico o electrónico que permite modificar el camino que deben seguir los electrones.

What does commutator mean in Electrical Engineering?

For the electrical component, see Commutator (electric). For the relation between canonical conjugate entities, see Canonical commutation relation. For other uses, see Commutation. In mathematics, the commutator gives an indication of the extent to which a certain binary operation fails to be commutative.

What is a commutator?

A commutator consists of a set of copper segments, fixed around the part of the circumference of the rotating machine, or the rotor, and a set of spring-loaded brushes fixed to the stationary frame of the machine.

How does a commutator work?

A commutator consists of a set of contact bars fixed to the rotating shaft of a machine, and connected to the armature windings. As the shaft rotates, the commutator reverses the flow of current in a winding. For a single armature winding, when the shaft has made one-half complete turn, the winding is now connected so that current flows through it in the opposite of the initial direction. In a motor, the armature current causes the fixed magnetic field to exert a rotational force, or a torque, on the winding to make it turn. In a generator, the mechanical torque applied to the shaft maintains the motion of the armature winding through the stationary magnetic field, inducing a current in the winding. In both the motor and generator case, the commutator periodically reverses the direction of current flow through the winding so that current flow in the circuit external to the machine continues in only one direction.

Why do commutators have three contact segments?

Practical commutators have at least three contact segments, to prevent a "dead" spot where two brushes simultaneously bridge only two commutator segments. Brushes are made wider than the insulated gap, to ensure that brushes are always in contact with an armature coil.

What are the disadvantages of commutators?

Although direct current motors and dynamos once dominated industry, the disadvantages of the commutator have caused a decline in the use of commutated machines in the last century. These disadvantages are: 1 The sliding friction between the brushes and commutator consumes power, which can be significant in a low power machine. 2 Due to friction, the brushes and copper commutator segments wear down, creating dust. In small consumer products such as power tools and appliances the brushes may last as long as the product, but larger machines require regular replacement of brushes and occasional resurfacing of the commutator. So commutated machines are not used in low particulate or sealed applications or in equipment that must operate for long periods without maintenance. 3 The resistance of the sliding contact between brush and commutator causes a voltage drop called the "brush drop". This may be several volts, so it can cause large power losses in low voltage, high current machines. Alternating current motors, which do not use commutators, are much more efficient. 4 There is a limit to the maximum current density and voltage which can be switched with a commutator. Very large direct current machines, say, more than several megawatts rating, cannot be built with commutators. The largest motors and generators are all alternating-current machines. 5 The switching action of the commutator causes sparking at the contacts, posing a fire hazard in explosive atmospheres, and generating electromagnetic interference.

How does armature current work?

In a motor, the armature current causes the fixed magnetic field to exert a rotational force, or a torque, on the winding to make it turn. In a generator, the mechanical torque applied to the shaft maintains the motion of the armature winding through the stationary magnetic field, inducing a current in the winding.

How many segments are in a commutator?

Commutator segments are connected to the coils of the armature, with the number of coils (and commutator segments) depending on the speed and voltage of the machine. Large motors may have hundreds of segments. Each conducting segment of the commutator is insulated from adjacent segments.

Do commutators have radial contact?

Although never reversed, common appliance motors that use wound rotors, commutators and brushes have radial-contact brushes. In the case of a reaction-type carbon brush holder, carbon brushes may be reversely inclined with the commutator so that the commutator tends to push against the carbon for firm contact.

Funcionamento

Os switches operam semelhantemente a um sistema telefónico com linhas privadas. Neste sistema, quando uma pessoa liga para outra, a central telefónica conecta-as numa linha dedicada, possibilitando um maior número de conversações simultâneas.A função básica de um switch é juntar ou conectar dispositivos em uma rede .

Métodos de comutação

Existem 4 metodos de comutação que um comutador pode usar, dos quais do segundo ao quarto apresentaram melhora de desempenho quando usados em produtos "comutados" com a mesma largura de banda de entrada e saída de porta:

Diferenças entre Switch L2 e L3

Switch L2 utiliza o endereço MAC (nível 2) contido no pacote de dados para enviar a informação, enquanto que o Switch L3 utiliza os endereços de nível 2 ou nível 3 (um exemplo é o endereço IP) para determinar o destino do pacote, permitindo que os pacotes sejam roteados.

Descrição geral

Funcionamento

Métodos de comutação

Diferenças entre Switch L2 e L3

Classificação

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Ligações externas