Fundamentos y Operaciones del Generador

Fundamentos del Generador - Objetivos Students must know magnets have lines of flux, if flux cuts a conductor a voltage is induced in the conductor. Make sure they understand a voltage is induced not a current. MVR – Manual voltage regulator, constant field, inc speed increase Vt, increase excitation increases Vt. AVR Auto voltage regulator, constant Vt, increase speed and still constant Vt. V/Hz limiter protects the Stator. Too much flux induces voltages in the stator key bars. Due to the arrangement of the Key bars and end rings current circulates and causes heat. I2R, Heat melts the varnish on the stator punchings. Heat creates smoke, not good One of the overheads asks the students to predict which phase is which. It keeps the students alert and interested PCM, PPT, MDA and MDB if applicable, OC Amperes field no load from Saturation curve

Líneas Magnéticas de Flujo siempre formaran __________________ ? Magnetos Permanente Magneto Hierro   Generator Off line fundamentals TB1-01 A) Explain the grade school experiment with the paper, iron filings and magnet and how this outlined the magnetic lines of flux. Draw a picture on board. Rather than draw filings go to OH 1.0 and show lines of flux as loops. Magnetic lines of flux make COMPLETE loops (On .PPT) 2) Magnetic lines of flux have direction always North to South (On .PPT) The purpose of stressing this point will be evident when creating a sine wave later. When the north pole cuts the conductor the voltage induced is of a certain polarity. When the south pole cuts the conductor the induced voltage polarity changes. 3) Magnetic lines of flux take the path of least reluctance, similar to current taking the path of least resistance. Flux goes through the Iron rather than air. (On .PPT) Líneas Magnéticas de Flujo siempre formaran __________________ ?

MMF = _________ x _____________ Electromagneto Generator Off line fundamentals TB 1 -02   1) Label the 3 components that create an Electromagnet: Power Source, Wire, Iron (On .PPT) 2) If there is a current flow there must be flux. (On .PPT) 3) What happens if current flow is increased? ( More flux, draw in more lines) (On .PPT) 4) If MMF represents the strength of the magnet what 2 factors determine how strong the magnetic field will be? (Amperes and turns, fill in blank) (On .PPT) 5) In the case of a generator rotor what can be varied? (Only amperes, turns better be fixed) 6) What does the hand represent? (Right hand rule, fingers in direction of current flow thumb points to North pole, Label on OH) (On .PPT) MMF = _________ x _____________ TB1-02

Conexiones de los anillos del Colector 1.) Discus how the rotor is an electro-magnet ( Use the wire around a nail analogy). Cuantas escobillas en una maquina? Que tan frecuentemente las escobillas deben ser observadas?

Flujo del Rotor ROTOR con Devanados de Campo A View A - A Generator Off line fundamentals   1) Explain the left view is a cross section of the right view 2) Demonstrate with an eraser and phone cord how a SINGLE wire is wrapped around the iron rotor. Then show how current flows down 1 side and back the other side. (Shown on .PPT) 3) Where’s the Rotor Poles, horizontal or vertical? (Shown on .PPT) (North on bottom) 3) 4) If you have current you must have flux. (On .PPT 5) Point out that the concentration of flux is at the poles. The poles are where there are no coils 6) 7) What happens if you increase current? (More flux) (Shown on .PPT) View A - A

Rotor del Generador

del campo para mantener los devanados del campo. El rotor es una sola pieza forjada con ranuras longitudinal cortadas adentro del cuerpo del campo para mantener los devanados del campo.

Devanados del Rotor Para que son los agujeros en el devanador del rotor? ____________________

Devanados del Rotor, gas frió para adentro, gas templado para afuera.

Las Cuñas que aguanta los devanados del rotor en su sitio tienen orificios para permitir que los gases entren y salga.

Componentes Conductores Sección transversal del Final del Colector

Ejemplo del Colector / Escobillas del Rotor de Campo

Ejemplo de un Rotor de Campo sin escobillas

Que podría ir mal? Que es esto?

Traten de arrancar a la velocidad del Turna Flecha, sin campo magnético, cerrando el interruptor del generador?

A la venta…….barato

A A Perspectiva A-A

Flujo de fuera de línea del Generador Patrones de Flujo adentro del generador.   Generator Off line fundamentals 1) STRESS drawing shows the flux inside a generator at rated terminal voltage OFF LINE (On .PPT ) 2) Color in Stator, Stator coils, Air Gap, Rotor and Rotor coils and Label    3) Ask, Where are the poles of the rotor? The poles of the rotor are where there are no field windings therefore the poles are horizontal (On.PPT) this will be referred to later when explaining load angle) 4) Note that the flux is symmetrical around the poles as expected, this is because all the flux is being generated by the rotor. 5) What would happen if current to the field increased? (Eventually the stator core would completely saturate, the magnetic lines of flux would travel outside the stator) 5) Students should note that off line at rated generator terminal voltage the stator is partially saturated and a small increase in field current from the exciter will fully saturate the stator. This is not good! En donde esta los polos del rotor? A donde esta el centro del campo?

Laminados del Estator ESTRUCTURA DEL NUCLEO DEL ESTATOR Note las Barras de llave LAMINACION del NUCLEO del ESTATOR MONTAGE DEL NUCLEO DEL ESTATOR ALINEAMIENTO EN LAS RANURAS DEL DEVANO DEL ESTATOR

Devanados del estator 1.) Roebel method ensures that each strand of copper has equal heating. This prevents any one copper strand from heating unevenly and expanding at different rates. This prevents the bus bar from expanding and possibly loosening. There more reasons than this but… Las barras del estator están compuestas de conductores de cobre aislados (hilos) transpuestos por el método "Roebel".

Devanados del estator 1.) The windings are bus bars and are manufactured out of individual strands of copper. El devanador de Campo esta compuesto de barras aisladas ensambladas en las ranuras del estator.

Para que se utilizan RTD’s (Los censores de resistencia de temperatura) ? En donde se encontraran la temperaturas mas alta segura del Devanador del Estator?

Donde están los polos en el rotor? Tensión inducida es Proporcional a: View A-A A Donde están los polos en el rotor? En este instante cual es la tensión inducida en uno de los devanado del Estator? Tensión inducida es Proporcional a:

Generator Off line fundamentals OH MF 08 Onda de CA   Generator Off line fundamentals OH MF 08 1) The picture in the lower left is similar previous ones, the rotor and conductor in the same position, the flux concentration is shown not the individual lines of flux. The remaining pictures show “snapshots” of the rotor/stator at 45 degree increments 2) Label the axis of the OH, Voltage and degrees rotor. 3) Label the degrees of the rotor 4) At 0 degrees what is the amount of induced voltage? ( max plot on OH) 5) At 45 degrees? (in between plot on OH) 6) At 90 degrees? ( 0 plot on OH) 7) At 135 the induced voltage is in between. Why is it opposite polarity? ( The lines of flux have direction, the flux is entering the coil in the opposite direction) 8) Explain what is meant by opposite polarity. You can use an example of a battery that’s terminals change polarity when you pass through 0. 9) Plot the last point 10) Connect the points in between and explain if points were plotted for every instant in time the voltage wave form would look like that. Using the blackboard show a voltage wave form of at least 360 degrees. Explain that every time the wave form repeats itself this is called 1 CYCLE or 1 frequency. 11) In the case of your generator in 1 revolution how many voltage cycles are produce? ( Unless it is a big machine 1 rev is 1 cycle) 12) How many revs per second?( 3000revs/min = 50 revs per second therefore 50 cycles per second or FREQ = 50HZ)

Requerimientos para Sincronizar Liste tres requerimientos para Sincronizar: 1) ____________________________________ 2) ____________________________________ 3) ____________________________________ Con el sistema de Control de sincronización de GE sincronización solo ocurrirá si: 1) ____________________________________ 2) ____________________________________ Cual es el método correcto de sacar un generador fuera de servicio?

Rotación de tres fase 1 2 Cual es Verde 1 o 2?

Flujo del Generador En-Servicio Patrones de flujo dentro del generador cuando la unidad esta: Donde están los polos del rotor? Donde esta el centro del flujo?

Power System Stabilizer FUERA DE SERVICIO POLOS EN SERVICIO FLUJO Nota: Hay un error, el diagrama debería tener el mismo numero de líneas de flujo. Cuando la unidad esta En-Servicio, como podría el ángulo de flujo cambiar?