Name: reducing power loss in three-phase lines
Uploaded: 2024-07-08T13:19:58.000Z
Duration: 1 min 10 s
Channel: JoVE

시간 영역에 표시되는 평형 3선 Y-Y 회로를 생각해 보십시오.이 회로는 위상별 등가 회로로 변환될 수 있습니다.
먼저 라인 전류가 결정된 다음 부하의 위상 전압이 결정됩니다.
그런 다음, 소스에 의해 전달되는 전력은 정현파 위상 전압 및 라인 전류의 유효 값을 사용하여 결정됩니다.
다음으로, 부하에 전달되는 전력은 라인 전류와 부하 저항을 사용하여 계산됩니다.
라인에서 손실된 전력은 라인 전류와 라인 저항을 사용하여 얻습니다.
그런 다음 3상 소스가 전달하는 총 전력, 3상 부하에 의해 수신된 총 전력 및 라인에서 손실된 총 전력이 결정됩니다.
라인에서 높은 비율의 전력이 손실되며, 이는 라인 전류를 최소화하여 줄일 수 있습니다.
그러나 이렇게 하면 부하 전류가 감소하여 부하에 전달되는 전력이 감소합니다.
부하 전류에 영향을 주지 않고 라인 전류를 줄이는 한 가지 방법은 3상 회로에 변압기를 도입하는 것입니다.

라인 손실

소스-부하 연결의 다양한 구성에는 Wye(스타) 연결과 델타 연결이 포함됩니다. 선상 및 상 전압과 전류 간의 관계는 구성에 따라 다릅니다. 소스에서 전력을 공급하면 전선을 통해 부하로 전달되며, 이 전송 중에 일부 전력이 전선에 흡수되어 선로 손실이 발생합니다.

라인 손실은 균형 잡힌 3상 회로의 전력 전달 효율성에 영향을 미칩니다. 이러한 회로의 대칭성은 단 하나의 위상만 고려함으로써 분석을 단순화합니다. 위상당 등가 회로는 라인 손실을 포함한 다양한 매개변수 계산을 돕습니다.

전력 손실 계산: 
부하의 각 상에 전달되는 전력은 위상 전류의 제곱과 위상 부하 저항의 곱입니다.

라인 손실 계산: 
각 와이어의 라인 손실은 라인 전류 크기의 제곱에 라인 저항을 곱하여 계산됩니다.

균형 잡힌 3상 시스템의 경우 이 계산에 3(각 위상당 하나씩)을 곱하여 총 전력 손실을 구합니다. 선의 저항은 물질의 저항률과 선의 길이에 정비례하고 도체의 단면적에 반비례합니다. 이는 선로 손실이 도체의 길이에 정비례하고 도체의 단면적에 반비례한다는 것을 의미합니다. 전력 회사는 선로 손실을 최소화하고 더 높은 전압에서 전력을 전송하기 위해 단면적이 더 큰 도체를 사용합니다. 이를 통해 동일한 전력량으로 더 낮은 전류를 사용할 수 있습니다. 이는 전력이 전압과 전류의 곱이기 때문이며, 주어진 전력 레벨에서 전압을 높이면 전류가 감소하여 라인 손실이 감소하기 때문입니다.

시간 영역에 표시되는 평형 3선 Y-Y 회로를 생각해 보십시오.이 회로는 위상별 등가 회로로 변환될 수 있습니다.
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Education

교육

JoVE Core

Electrical Engineering

전기공학

Unit 1

제1단원

Three-Phase Circuits

3상 회로

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 helps calculate the power delivered to the load and the power lost in the lines.

For each phase of the load, the delivered power depends on the square of the phase current and the phase load resistance. The power lost in one wire is found from the square of the line current multiplied by the resistance of that line. For a balanced three-phase system, the total line loss is three times the loss in one phase.

Line resistance depends on the material resistivity, the length of the conductor, and its cross-sectional area. As the line gets longer, resistance and line loss increase. A larger cross-sectional area lowers resistance and helps reduce loss. Power companies use larger conductors and higher transmission voltages to keep current lower for the same power level, which reduces line loss.

Reducing Power Loss in Three-Phase Lines

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

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

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 three-phase circuits, wye and delta connections, and conductor size affect line loss, power delivery, and transmission efficiency.

Reducing Power Loss in Three-Phase Lines | 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

Reducing Power Loss in Three-Phase Lines

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