Name: delta-wye source and load connections
Uploaded: 2024-07-08T13:19:57.000Z
Duration: 1 min 16 s
Channel: JoVE

平衡型デルタ/Y型システムは、平衡型Y接続負荷に電力を供給する平衡型デルタ接続ソースを特長としています。
このデルタY回路では、正のabcシーケンスが位相電圧を表すと想定されており、これはデルタ接続されたソースのライン電圧としても機能します。
キルヒホッフの電圧則を回路内のループに適用して、2つのライン電流間の関係を導き出すことができます。
正のシーケンスが想定されるため、これらのライン電流の位相差は120度で、これを使用してそのうちの1つが決定されます。
他の2つのライン電流は、正の位相シーケンスを使用して取得されます。
デルタY回路の位相電流は、ライン電流とほぼ等しくなります。
または、デルタ接続のソースを、同等の Y 接続のソースに置き換えることもできます。
得られたY-Y回路は、等価単相回路を考慮し、3ライン電流を決定することによって分析されます。
この回路は、個々の負荷の変更が容易なため、デルタ接続の負荷が好まれることが多いため、分析目的でデルタデルタシステムに変換することもできます。

Δ-y回路

Δ-Y回路では、ソースはΔ結線され、負荷は Y 構成になっています。つまり、Δ結線されたソースの位相電圧は、Y 接続された負荷の線間電圧に等しくなります。2 つの線間電流の接続は、デルタ接続されたソースから発生します。バランスのとれたシステムでの位相差により、正の位相シーケンスを使用して、一方の線電流からもう一方の線電流を計算できます。Δ-Y システムでは、Y 接続された負荷の位相電流は、Δソースからの線電流に直接等しくなります。これは、負荷の Y 構成によってΔソースからの流れが簡素化されるためです。Y 構成での線電流と位相電流の関係から、Y 接続された負荷の位相電流は、Δ結線されたソースの線電流に等しくなります。

線電流を取得する別の方法は、Δ接続電源を同等の Y 接続電源に置き換えることです。Y 接続電源の線間電圧は、対応する位相電圧より 30 度進みます。つまり、同等の Y 接続電源の各位相電圧は、Δ接続電源の対応する線間電圧を 3 の平方根で割り、位相を -30 度シフトすることで得られます。その結果、同等の Y 接続電源の位相電圧はそれに応じて 120 度シフトします。

Δ結線をスター結線に変換することで、システムはより優れた電圧調整を実現し、中性線の使用が可能になります。この中性線によりシステムの接地が可能になり、安全性と安定性が向上します。
バランスのとれたΔ-Δ結線は、高電圧レベルを工業、商業、住宅で使用可能なレベルまで下げる必要がある長距離の送電に使用されます。

Δ-Y回路

平衡型デルタ/Y型システムは、平衡型Y接続負荷に電力を供給する平衡型デルタ接続ソースを特長としています。
このDELTA-Y回路では、正のabc ...

Education

JoVE Core

Electrical Engineering

電気工学

Unit 1

ユニット1

Three-Phase Circuits

三相回路

KEY TERMS AND CONCEPTS

主要用語および概念

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. That relationship makes current analysis simpler in the load section.

The line currents can also be found by replacing the delta source with an equivalent wye source. In that conversion, each phase voltage is the matching line voltage divided by the square root of three and shifted by -30 degrees. The line-to-line voltages of a wye source lead the phase voltages by 30 degrees, so the equivalent wye source keeps the phases spaced 120 degrees apart.

Changing a delta connection to a star, or wye, connection can improve voltage regulation. It also allows the use of a neutral wire. That neutral wire supports grounding, which improves safety and stability. Balanced delta systems are also used for long-distance power transmission, where high voltage must later be stepped down for industrial, commercial, and residential use.

Delta-Wye Source and Load Connections

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

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 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

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 a balanced delta source powers a wye load, how line and phase currents relate, and how a delta source can be converted to an equivalent wye source.

Delta-Wye Source and Load Connections | JoVE K12

JoVE Core 電気工学 は、電気回路の基本概念と回路解析テクニックを網羅したアニメーションビデオシリーズです。オペアンプと回路変換および 1 次・ 2 次回路の概念を網羅しています。実験を撮影した実写動画では、設計例や現代社会での応用が含まれており、複雑な概念も分かりやすく学習いただけます。

electrical engineering

Delta-Wye Source and Load Connections

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