Name: three-phase power connections
Uploaded: 2024-07-08T13:19:57.000Z
Duration: 1 min 30 s
Channel: JoVE

En los sistemas trifásicos de cuatro hilos, tres fuentes de voltaje conectadas en Y generan voltajes de fase equilibrados.
Hay dos secuencias de fase basadas en el orden en que los voltajes de fase alcanzan sus valores máximos.
La primera, abc o secuencia positiva, involucra fasores que giran en sentido contrario a las agujas del reloj, con Vy Vbn principal, que conduce a Vcn. Esta secuencia se produce cuando el rotor gira en sentido contrario a las agujas del reloj.
La segunda, acb o secuencia negativa, tiene fasores que giran en sentido contrario a las agujas del reloj, y Van conduce a Vcn, que conduce a Vbn. Esta secuencia corresponde a la rotación del rotor en el sentido de las agujas del reloj.
Al igual que las fuentes de voltaje, las tres cargas pueden estar conectadas en Y o en triángulo.
En configuraciones de carga equilibrada, las impedancias de fase son iguales en magnitud y fase.
Las cargas conectadas en Y se pueden transformar en configuración delta y viceversa.
En función de las configuraciones de la fuente y la carga trifásicas, existen cuatro conexiones posibles.
Las cargas conectadas en delta son más comunes que la configuración en Y debido a la facilidad de agregar y eliminar cargas de fases individuales sin causar desequilibrios excesivos.
Sin embargo, las fuentes conectadas en triángulo son menos comunes que las fuentes conectadas en Y debido a la corriente circulante en la malla delta cuando los voltajes trifásicos están ligeramente desequilibrados.

voltajes trifásicos

Un generador trifásico produce tres voltajes de igual magnitud pero con una diferencia de fase de 120 grados. Esta magnitud idéntica y voltajes separados por fases iguales se conocen como voltajes equilibrados y ayudan a minimizar la pérdida de energía al tiempo que garantizan una entrega constante de energía a las cargas conectadas. Como las fuentes de voltaje en un sistema trifásico pueden configurarse en estrella o en Triángulo, las cargas conectadas a estos sistemas también pueden disponerse en cualquiera de las dos configuraciones. Esta flexibilidad en la configuración de la carga no es sólo una elección de diseño sino una forma de ejercer control sobre el sistema. Las cargas conectadas en triángulo tienen un extremo de cada devanado de fase conectado a un punto neutro común. Por el contrario, en cargas conectadas en triángulo, los extremos de los devanados de fase están conectados en un bucle continuo, formando un triángulo. Un sistema trifásico utiliza sistemas de cuatro y tres hilos a través de conexiones en Estrella y en triángulo. Los voltajes trifásicos en configuración estrella son:
<img alt="Equation 1" src="/files/ftp_upload/15128/15128_Equation_1.svg" style="height: 16px;">
<img alt="Equation 2" src="/files/ftp_upload/15128/15128_Equation_2.svg" style="height: 16px;">
<img alt="Equation 3" src="/files/ftp_upload/15128/15128_Equation_3.svg" style="height: 16px;">
Comprender la secuencia lógica de las tres fases es clave. Cuando están en las secuencias positiva y a-b-c, los fasores giran en sentido antihorario, con V_an liderando a V_bn, seguido de V_cn. Esta secuencia, resultante del giro del rotor en sentido antihorario, es una progresión clara y ordenada.
En la secuencia negativa a-c-b, los fasores giran en el sentido de las agujas del reloj, con V_an delante de V_cn y V_bn en último lugar. Esto indica un orden de fase inverso en comparación con la secuencia positiva, que corresponde a la rotación del rotor en el sentido de las agujas del reloj.
Cada configuración, ya sea conectada en estrella o en triángulo, permite una condición de carga equilibrada e influye en la distribución y gestión de voltajes y corrientes del circuito. Durante las configuraciones de carga equilibrada, las impedancias conectadas en cada fase son iguales en magnitud y fase, lo que permite gestionar su sistema de forma eficaz.
Las cargas conectadas en estrella se pueden transformar en configuración Triángulo y viceversa. Según los tipos de conexión de la fuente y la carga, el sistema se puede configurar de cuatro formas principales: Estrella-Estrella, Estrella-Triángulo, Triángulo-Estrella y Triángulo-Triángulo.

Voltajes Trifásicos

En los sistemas trifásicos de cuatro hilos, tres fuentes de voltaje conectadas en Y generan voltajes de fase equilibrados.
Hay dos secuencias de fase basadas en el orden ...

Education

Educación

JoVE Core

Electrical Engineering

Ingeniería Eléctrica

Unit 1

Unidad 1

Three-Phase Circuits

Circuitos trifásicos

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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 phase winding connects to a common neutral point. In a delta connection, the phase windings join end to end in a closed triangle.

A three-phase system may use four-wire or three-wire connections through star and delta arrangements. The phase order also matters. In the positive a-b-c sequence, the phasors rotate anticlockwise, with V an leading V bn and V cn following. This sequence matches counterclockwise rotor rotation. In the negative a-c-b sequence, the phasors rotate clockwise, with V an leading V cn and V bn last. This reversed order matches clockwise rotor rotation.

Balanced load conditions are important in both wye-connected and delta-connected systems. In a balanced load, the impedances across each phase are equal in magnitude and phase. That balance helps the circuit manage voltages and currents more effectively. Star-connected loads can also be transformed into delta form, and delta loads can be transformed into star form. Based on the source and load connections, a three-phase system can be set up as wye-wye, wye-delta, delta-wye, or delta-delta.

Three-Phase Power 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 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

Learn how three-phase power uses balanced voltages, wye and delta connections, phase sequence, and balanced loads to control voltage and current flow.

Three-Phase Power Connections | 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

Three-Phase Power Connections

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