Name: balanced wye-to-wye neutral current
Uploaded: 2024-07-08T13:19:57.000Z
Duration: 1 min 19 s
Channel: JoVE

Os sistemas Y-to-Y balanceados de quatro fios consistem em três fontes de tensão senoidal conectadas em Y balanceadas e cargas com o fio neutro conectando ambos os nós neutros da fonte com a carga.
A impedância de carga para cada fase é igual à soma das impedâncias de origem, linha e carga. As impedâncias de fonte e linha são negligenciadas para simplificar o sistema.
Considerando a sequência de fases positivas, as tensões de fase determinam as tensões de três linhas
A Lei de Tensão de Kirchhoff é aplicada a cada fase, e as correntes de linha são determinadas como tendo magnitudes iguais e diferenças de fase de 120 graus.
Sua soma é igual a zero, implicando corrente zero no fio neutro.
Em um sistema Y balanceado, a potência total fornecida à carga trifásica é três vezes a potência fornecida em cada fase.
Para um sistema Y-to-Y desbalanceado com uma carga desbalanceada, as correntes de linha são desequilibradas, resultando em uma corrente neutra diferente de zero.
Outro método de análise de um sistema Y-to-Y balanceado é considerar uma fase e analisar seu circuito equivalente monofásico para determinar sua corrente de linha. A sequência de fases produz as outras duas correntes de linha.

o circuito y-to-y

The Y-to-Y Circuit

Em um sistema estrela-estrela balanceado de quatro fios, o arranjo envolve fontes e cargas de tensão senoidal conectadas em estrela, conectadas através de um fio neutro que liga os nós neutros da fonte e da carga. A impedância de carga é conectada em cada fase da carga. A fonte conectada em estrela pode ser conectada à carga conectada em estrela em arranjos de quatro e três fios. Um sistema trifásico é considerado equilibrado quando a carga em cada fase é igual, levando a um fluxo de corrente e ângulo de fase uniformes em todos os estágios. Por outro lado, num sistema desequilibrado, variações na impedância da carga ou nas tensões da fonte resultam em correntes de linha desiguais.

A análise da configuração do circuito estrela-estrela de quatro fios é relativamente simples. Nesta configuração, cada impedância da carga trifásica é conectada diretamente à sua respectiva tensão de fase da fonte trifásica. Assumindo uma sequência de fases positiva e condições equilibradas, as tensões de fase são fundamentais na análise do sistema. Essas tensões de fase influenciam diretamente as tensões em cada impedância de carga.

<img alt="Equation 1" src="/files/ftp_upload/15129/15129_Equation_1.svg" style="height: 32px;">

<img alt="Equation 2" src="/files/ftp_upload/15129/15129_Equation_2.svg" style="height: 32px;">

<img alt="Equation 3" src="/files/ftp_upload/15129/15129_Equation_3.svg" style="height: 32px;">

A corrente no fio que conecta o nó neutro da fonte ao nó neutro da carga é:

<img alt="Equation 4" src="/files/ftp_upload/15129/15129_Equation_4.svg" style="height: 16px;">

A Lei de Tensão de Kirchhoff, quando aplicada a cada fase de um circuito trifásico balanceado, confirma que a soma das tensões em qualquer circuito fechado é zero. Isto leva a correntes de linha de igual magnitude, mas com mudanças de fase de 120 graus entre elas. Essas correntes efetivamente somam zero em qualquer ponto, o que justifica porque o fio neutro não transporta corrente em condições equilibradas.

Em um sistema estrela-estrela desequilibrado, variações na impedância da carga ou nas tensões da fonte resultam em correntes de linha desiguais. Cada fase do sistema é tratada como um circuito monofásico para calcular sua corrente de linha. No entanto, as correntes para as restantes fases requerem análise individual em vez de dedução baseada apenas na sequência de fases, uma vez que cada fase pode ser influenciada exclusivamente pelas suas condições elétricas específicas.

O Circuito Y-To-Y

Os sistemas Y-to-Y balanceados de quatro fios consistem em três fontes de tensão senoidal conectadas em Y balanceadas e cargas com o fio neutro conectando o ...

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balanced wye-to-wye neutral current

A balanced wye-to-wye circuit uses three wye-connected sinusoidal voltage sources and three wye-connected loads. A neutral wire links the neutral node of the source to the neutral node of the load. The load impedance is connected across each phase of the load.

The source and load can be connected in either a four-wire or a three-wire arrangement. A three-phase system is balanced when each phase has the same load. In that case, the current flow and phase angle are uniform across the system. If the load impedance or source voltages differ, the system becomes unbalanced and the line currents are no longer equal.

The four-wire wye-wye circuit is relatively easy to analyze. Each load impedance is connected directly across its own phase voltage from the three-phase source. With a positive phase sequence and balanced conditions, the phase voltages are the key to finding the voltages across each load impedance.

Kirchhoff's Voltage Law applies to each phase of a balanced three-phase circuit. The sum of the voltages around any closed loop is zero. This produces line currents with equal magnitude and 120-degree phase shifts. Their sum is zero at any point, so the neutral wire carries no current when the system is balanced.

An unbalanced wye-to-wye system must be treated differently. Changes in load impedance or source voltages create unequal line currents. Each phase is handled as a single-phase circuit to find its line current. The other phases must be analyzed on their own, since each one may be affected by its specific electrical conditions rather than by phase sequence alone.

Balanced Wye-to-Wye Neutral Current

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A balanced wye-to-wye circuit uses three wye-connected sinusoidal voltage sources and three wye-connected loads. A neutral wire links the neutral node of the source to the neutral node of the load. The load impedance is connected across each phase of the load. The source and load can be connected in either a four-wire or a three-wire arrangement. A three-phase system is balanced when each phase has the same load. In that case, the current flow and phase angle are uniform across the system. If...

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A balanced delta-wye circuit connects a delta-connected source to a wye-connected load. In this setup, the phase voltage of the delta source equals the line voltage of the wye load. The source also sets the line currents that flow into the load. For a balanced system, the phase difference between currents makes it possible to find one line current from the other by using the positive sequence of phases. In the wye-connected load, each phase current equals the line current from the delta source.

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Learn how balanced and unbalanced wye-to-wye circuits work, why the neutral wire carries no current in balanced conditions, and how line currents are analyzed.

Balanced Wye-to-Wye Neutral Current | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

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Balanced Wye-to-Wye Neutral Current

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