Name: how three-phase power delivers electricity
Uploaded: 2024-07-08T13:19:57.000Z
Duration: 1 min 22 s
Channel: JoVE

일반적으로 AC 배전 시스템은 단상, 2상 또는 3상으로 분류됩니다.
단상 회로에는 2선식 시스템을 통해 부하에 연결된 단일 소스가 포함됩니다.
단상 시스템은 가정에서 램프, TV 또는 중앙 에어컨과 같은 120V 및 240V 기기에 전력을 공급하는 데 사용됩니다.
2상 3선식 시스템에는 두 개의 소스가 있으며, 두 번째 소스에서 생성된 전압은 다른 소스보다 90도 뒤처집니다.
대조적으로, 3상 4선식 시스템은 진폭, 주파수 및 위상차가 120도이고 3개의 부하에 연결된 3개의 소스로 구성됩니다.
3상 소스 및 3상 부하는 Y 또는 델타 연결일 수 있습니다.
이 회로는 유도 전동기에 전원을 공급하는 것과 같은 산업 응용 분야에 사용되며 필요한 경우 단상 입력을 제공하는 데 사용할 수 있습니다.
이러한 시스템의 순간 전력은 단상 시스템에서 전달되는 것보다 훨씬 낮은 맥동을 가지므로 보다 균일한 동력 전달과 더 적은 진동을 보장합니다.
동일한 전력을 전달하기 위해 더 적은 도체 재료나 와이어가 필요하므로 단상보다 경제적입니다.

3상 회로

Three-Phase Circuits

AC 배전 시스템에는 단상, 2상 및 3상 시스템의 세 가지 범주가 있습니다. 주거 환경에서 흔히 사용되는 단상 회로는 일반적으로 단일 AC 소스를 다양한 부하에 연결하는 2선 시스템을 사용합니다. 이 회로는 램프, TV, 전자레인지와 같이 120V 및 240V에서 작동하는 표준 가전 제품을 지원합니다. 1895년에 설치된 최초의 발전기인 나이아가라 폭포 수력 발전소는 2상 발전기였으며 니콜라 테슬라가 설계했습니다. 2상 공급 시스템은 덜 일반적이며 3선 시스템은 서로 90도 위상이 다른 2개의 전압 소스를 통합합니다.
3상 4선 시스템은 산업 응용 분야에서 가장 널리 사용됩니다. 이 시스템은 진폭과 주파수가 동일하지만 서로 120도의 위상차를 갖는 3개의 AC 소스로 구성됩니다. 이러한 시스템의 부하는 Y(별) 구성 또는 델타(Δ) 구성으로 연결될 수 있습니다.
3상 회로의 장점은 효율성과 안정성에 있습니다. 단상 시스템보다 낮은 맥동으로 전력을 공급하므로 더 부드러운 전력 전달이 가능하고 진동이 최소화됩니다. 이는 유도 전동기와 같은 산업 기계에 중요한 요소입니다. 또 다른 이점은 주어진 양의 전력을 전송하는 데 필요한 도체 재료의 양이 줄어들어 3상 시스템이 단상 시스템보다 비용 효율적이라는 점입니다.
Y로 연결된 3상 시스템의 선간 및 상 전압과 전류 간의 관계는 다음과 같습니다.
<img alt="Equation 1" src="/files/ftp_upload/15126/15126_Equation_1.svg" style="height: 22px;">

<img alt="Equation 2" src="/files/ftp_upload/15126/15126_Equation_2.svg" style="height: 22px;">
Δ 연결 시스템의 경우:
<img alt="Equation 3" src="/files/ftp_upload/15126/15126_Equation_3.svg" style="height: 20px;">

<img alt="Equation 4" src="/files/ftp_upload/15126/15126_Equation_4.svg" style="height: 22px;">
이 방정식은 선간 전압과 전류 사이의 관계를 각 상의 전류와 보여줍니다. 이는 3상 시스템에서 총 전력을 계산할 때 필수적입니다. Y 및 Δ 연결 모두에 대한 총 전력은 다음을 사용하여 찾을 수 있습니다.
<img alt="Equation 5" src="/files/ftp_upload/15126/15126_Equation_5.svg" style="height: 20px;">
여기서 ϕ 는 전력 전송 효율에 영향을 미치는 역률 각도입니다.

일반적으로 AC 배전 시스템은 단상, 2상 또는 3상으로 분류됩니다.
단상 회로는 단일 소스를 포함합니다 ...

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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 and 240 V.

Two-phase supply systems are less common. The first generators at the Niagara Falls hydro plant, installed in 1895, used two-phase power and were designed by Nikola Tesla. In a two-phase system, a three-wire setup uses two voltage sources that are 90 degrees out of phase.

Three-phase systems are used most often in industrial settings. A three-phase, four-wire system uses three AC sources with the same amplitude and frequency, and each source is shifted by 120 degrees. Loads in these systems can be connected in a Y, or star, configuration or in a delta (Δ) configuration.

Three-phase circuits are valued for efficiency and stability. They deliver power with less pulsation than single-phase systems, so the flow is smoother and vibrations are reduced. This matters for industrial machines such as induction motors. Three-phase systems also need less conductor material to deliver the same amount of power, which makes them more cost-effective than single-phase systems.

The line and phase values are related differently in Y-connected and Δ-connected systems. These relationships between line-to-line voltage and current and the values in each phase are important when calculating total power. Total power in both Y and Δ connections is found using an equation that includes the power factor angle, φ, which affects power transmission efficiency.

How Three-Phase Power Delivers Electricity

how-three-phase-power-delivers-electricity

three-phase circuits

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

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

Explore how three-phase AC power works, why industry uses Y and delta connections, and how smoother, more efficient power delivery is calculated.

How Three-Phase Power Delivers Electricity | 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

How Three-Phase Power Delivers Electricity

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