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

평형 4선식 Y-Y 시스템은 3개의 평형 Y-연결 정현파 전압 소스와 부하로 구성되며, 중성선은 소스의 중성 노드를 부하와 연결합니다.
각 위상에 대한 부하 임피던스는 소스, 라인 및 부하 임피던스의 합과 같습니다. 소스 및 라인 임피던스는 시스템을 단순화하기 위해 무시됩니다.
양의 위상 순서를 고려할 때, 위상 전압은 3선 전압을 결정합니다
Kirchhoff의 전압 법칙은 각 위상에 적용되며 라인 전류는 동일한 크기와 120도 위상 차이를 갖는 것으로 결정됩니다.
그들의 합은 0과 같으며 중성선의 전류가 0임을 의미합니다.
균형 잡힌 Y 시스템에서 3상 부하에 전달되는 총 전력은 각 상에서 전달되는 전력의 3배입니다.
불균형 부하가 있는 불균형 Y-Y 시스템의 경우 라인 전류가 불균형하여 0이 아닌 중성 전류가 발생합니다.
균형 잡힌 Y-Y 시스템을 분석하는 또 다른 방법은 단상을 고려하고 단상 등가 회로를 분석하여 라인 전류를 결정하는 것입니다. 그런 다음 위상 시퀀스는 다른 두 개의 라인 전류를 생성합니다.

y-to-y 회로

균형 잡힌 4선 Wye-to-Wye 회로의 배열에는 소스와 부하의 중성 노드를 연결하는 중성선을 통해 연결된 Y형 연결 정현파 전압 소스 및 부하가 포함됩니다. 부하 온저항은 부하의 각 위상에 걸쳐 연결됩니다. Y결선 소스는 4선 및 3선 배열로 Y결선 부하에 연결될 수 있습니다. 3상 시스템은 각 위상의 부하가 동일할 때 균형이 잡힌 것으로 간주되어 모든 스테이지에서 전류 흐름과 위상 각도가 균일해집니다. 반면, 불균형 시스템에서는 부하 온저항 또는 소스 전압의 변화로 인해 라인 전류가 동일하지 않게 됩니다.
4선 와이와이 회로 구성 분석은 비교적 간단합니다. 이 설정에서 3상 부하의 각 온저항은 3상 소스의 해당 위상 전압에 직접 연결됩니다. 양의 위상 시퀀스와 균형 잡힌 조건을 가정하면 위상 전압은 시스템을 분석하는 데 중요한 역할을 합니다. 이러한 위상 전압은 각 부하 온저항의 전압에 직접적인 영향을 미칩니다.
<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;">
소스의 중성 노드를 부하의 중성 노드에 연결하는 와이어의 전류는 다음과 같습니다.
<img alt="Equation 4" src="/files/ftp_upload/15129/15129_Equation_4.svg" style="height: 16px;">
키르히호프의 전압 법칙을 균형 잡힌 3상 회로의 각 상에 적용하면 폐루프 주변의 전압 합이 0임을 확인합니다. 이로 인해 동일한 크기의 선 전류가 발생하지만 그 사이에 120도 위상 변이가 발생합니다. 이러한 전류는 어느 지점에서나 효과적으로 합산되어 0이 됩니다. 이는 균형 잡힌 조건에서 중성선이 전류를 전달하지 않는 이유를 정당화합니다.
불균형한 Wye-to-Wye 시스템에서는 부하 온저항 또는 소스 전압의 변화로 인해 라인 전류가 동일하지 않게 됩니다. 시스템의 각 위상은 라인 전류를 계산하기 위해 단상 회로로 처리됩니다. 그러나 나머지 위상에 대한 전류는 각 위상이 특정 전기적 조건에 의해 고유하게 영향을 받을 수 있으므로 위상 순서만을 기반으로 추론하기보다는 개별 분석이 필요합니다.

Y-to-Y 회로

평형 4선식 Y-Y 시스템은 3개의 평형 Y-연결 정현파 전압 소스와 부하로 구성되며 중성선은 두 가지를 모두 연결합니다.

Education

교육

JoVE Core

Electrical Engineering

전기공학

Unit 1

제1단원

Three-Phase Circuits

3상 회로

KEY TERMS AND CONCEPTS

주요 용어 및 개념

The Y-to-Y Circuit

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

three-phase circuits

How Three-Phase Power Delivers Electricity

Three-phase power is a major part of AC power distribution, especially where steady and efficient electricity delivery is needed. AC systems are grouped into single-phase, two-phase, and three-phase systems. These categories help describe how power moves from the source to the load. Single-phase circuits are common in homes. They usually use a two-wire system that connects one AC source to loads. These circuits can supply everyday appliances such as lamps, televisions, and microwaves at 120 V...

generation of three-phase voltage

Three-Phase AC Generator Windings

A three-phase AC generator uses rotating magnet windings and a stationary stator to make three-phase voltage. The rotor carries a magnet that spins inside the stator. The stator holds the three-phase winding, and mutual induction creates the voltage. The stator windings are spread evenly around the inside of the stator. They are placed 120 electrical degrees apart. These windings consist of three separate coils, or groups of coils, called phases. The phases can be connected in a Y, or star,...

three-phase voltages

Three-Phase Power Connections

Three-phase power connections use balanced voltages that are equal in magnitude and separated by 120 degrees. A three-phase generator produces these voltages, and the balance helps reduce power loss while keeping energy delivery steady to connected loads. Three-phase sources can be arranged in either wye or delta form. The loads connected to the system can also use wye or delta. This flexibility gives control over how the system is designed and managed. In a wye connection, one end of each...

the y-to-y circuit

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 y-to-delta circuit

Wye Source and Delta Load Currents

A balanced wye source and delta load form a common three-phase circuit with no neutral line connection. The source is Y-connected, and the load is delta-connected. To analyze the circuit, the first step is to assume a positive phase sequence. These phase voltages are then used to find the line voltages that appear across the delta load impedances. In the wye source, the phase voltages are V an, V bn, and V cn. In the delta load, the line voltages are V ab, V bc, and V ca. These line voltages...

the delta-to-delta circuit

Balanced Delta-Delta Power Circuit

A balanced delta-delta power circuit uses a delta-connected source and a delta-connected load. The two deltas form a closed loop that creates three separate phases. In this setup, the phase voltages are the same as the line voltages. If the source is in positive sequence, the phase voltages can be written directly, and no neutral wire is needed. The delta-connected load current is found by dividing the phase voltage by the impedance of each phase. For line current, Kirchhoff’s Current Law...

the delta-to-y circuit

Delta-Wye Source and Load Connections

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.

power in a three-phase circuit

Balanced Three-Phase Power Calculation

Balanced three-phase power calculation depends on the wye and delta connections used in the circuit. A wye, or star, configuration can use three wires or four wires. A delta configuration connects the components in a closed loop. These connection types change how voltages and currents are arranged, but both are used in three-phase systems. In a balanced three-phase system, instantaneous power is the power at one exact moment. Even though the power in each phase changes over time, the total...

power distribution in three-phase and single phase circuits

power-distribution-in-three-phase-and-single-phase-circuits

Single-Phase vs. Three-Phase Power Loss

Single-phase and three-phase circuits distribute electrical power in different ways. Single-phase power is common in homes, while balanced three-phase power is widely used in industrial settings with heavy machinery. Both systems deliver energy, but their current flow and wire needs are not the same. A single-phase circuit usually uses a two-wire system. The current depends on the power absorbed by the load and the line voltage. Because wire loss from resistance follows the square of the...

line loss

Reducing Power Loss in Three-Phase Lines

Three-phase power lines can lose energy as electricity travels from the source to the load. This line loss affects how efficiently power reaches the load. In balanced three-phase circuits, the symmetry makes the analysis easier because one phase can represent the whole system. The source-load connection can use wye, also called star, or delta configurations. These setups change the relationship between line voltage, phase voltage, line current, and phase current. A per-phase equivalent circuit...

reducing line loss

Cutting Heat Loss in Three-Phase Lines

Three-phase power systems can lose energy as heat in transmission lines because the wires have resistance. This line loss becomes important when electricity travels over a distance. A common solution is to use transformers to change the voltage and current in the system. The setup uses two three-phase transformers. A step-up transformer is placed at the source, and a step-down transformer is placed at the load. Raising the voltage at the source lowers the current in the transmission lines, and...

key terms and concepts

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.

electrical engineering

Balanced Wye-to-Wye Neutral Current

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