RESUMAO FUNDAMENTOS DE MÁQUINAS P2

8/7/2019 RESUMAO FUNDAMENTOS DE MQUINAS P2

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TRANSFORMADORES:

Enrolamento primrio: conectado fonte

Enrolamento secundrio: conectado carga

Transformador ideal: no muda os ngulos de defasagem de Vp e Vs, Ip e Is, somente as suas

magnitudes

A potncia no enrolamento primrio a mesma do que a do secundrio

Circuito Equivalente:

Diferentes voltagens:


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Nveis de voltagem iguais:

O circuito pode ser aproximado para:


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Portanto as converses das impedncias para referencia no primrio sero:

Eficincia:

Regulao:

Um baixo valor de regulao indica que uma variao de carga no enrolamento secundrio do

trafo no afetar significativamente a magnitude da voltagem suprida carga.

Clculo dos parmetros:

Curto Circuito:

Lado de alta (primrio) > aplica a tenso Lado de Baixa > curto circuitado Isc , Vsc , Vsc


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AUTOTRANSOFORMADOR

No faz isolamento eltrico Requer menor corrente de excitao


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TRANSFORMADORES TRIFSICOS


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PRINCPIOS DE CONVERSO ELETROMECNICA (How energy conversion takes place...)

Monoexcitao em sistemas lineares:

The interaction between the electric and mechanical terminals, i.e., the electromechanical

energy conversion, occurs through the medium of the magnetic stored

Assumption that it is possible to separate the losses out of the physical problem :

Energia do campo magntico:


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Fora magntica:


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Monoexcitao em sistemas rotativos

Torque:

CO-ENERGIA

The selection of energy or coenergy as the state function is purely a matter of convenience;

they both give the same result, but one or the other may be simpler analytically, depending on

the desired result and the characteristics of the system being analyzed.

Monoexcitao em sistemas linearesFora magnetica:


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Monoexcitao em sistemas rotativos


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The algebraic signs in Eqs. 3.26 and 3.40 show that the force acts in a direction to decrease

the magnetic field stored energy at constant flux or to increase the coenergy at constant

current. In a singly-excited device, the force acts to increase the inductance by pulling on

members so as to reduce the reluctance of the magnetic path linking the winding

Lembrando que:

To understand the behavior of rotating machinery, a simple physical picture is quite useful.

Associated with the rotor structure is a magnetic field (produced in many machines by

currents in windings on the rotor), and similarly with the stator; one can picture them as a set

of north and south magnetic poles associated with each structure. Just as a compass needle

tries to align with the earth's magnetic field, these two sets of fields attempt to align, and

torque is associated with their displacement from alignment. Thus, in a motor, the stator

magnetic field rotates ahead of that of the rotor, pulling on it and performing work. Theopposite is true for a generator, in which the rotor does the work on the stator.


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Multiexcitao em sistemas linearesA funo diferencial da energia:

As relaes entre os fluxos concatenados e as correntes i so:

A energia sera portanto:

Coenergia :

Fora:


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Multiexcitao para sistemas rotativos :

Torque :

Na equao do torque:

Termo proporcioal a i1 e i2 > devido interao mtua das corrente, atua em uma direoque alinhe o rotor e o estator para maximizar sua indutncia mtua. Pode ser visto como a

tendncia de dois campos magnticos se alinharem

Os outros termos so funo da posio do rotor e o torque correspondente age de forma amaximizar as indutncias prprias e assim maximizar a coenergia. A variao de 2

corresponde variao da indutncia prpria.

RESUMAO FUNDAMENTOS DE MÁQUINAS P2

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