The three-phase alternator, Electrical Engineering

The Three-phase alternator

In this case, three separate sets of coils are wound on the stator and connected to produce three separate outputs. Because of the physical displacement of the coils around the stator, the outputs will have different phases with respect to each other. Three-phase systems are common even when DC outputs are required (e.g. electric alternators to charge a car battery) because of the torque reaction problem mentioned above. The AC output is rectified with a set of six diodes mounted in a single pack (two diodes are needed to rectify each phase).

A  two-pole, three-phase alternator is shown in the diagram below. Stator coils AB belong to phase 1, coils CD to phase 2 and coils EF to phase 3. Each pair of coils are connected  in series and their outputs add (e.g. A and B are connected in series to  produce  phase  1  output).  Notice  it  is two-pole because there are only two poles (i.e. one pole pair) on the rotor. The frequency of each phase output is therefore equal to the rotational speed of the rotor.

1357_The Three-phase alternator.png

 

 

 

Unlike the single-phase  alternator, it turns out  that  the  torque  required  to  drive  a three-phase alternator is constant, with no pulsating component. This is an important advantage.The figure below shows the arrangement for   a     multipole   three-phase   alternator. Again, coils A&B, C&D and E&F are connected in series to three differnet outputs, each with a phase shift  of 120° apart (because of the physical arrangement of the coils on the stator).

1646_Three-phase alternator.png

 

 

Posted Date: 8/23/2012 2:24:31 AM | Location : United States







Related Discussions:- The three-phase alternator, Assignment Help, Ask Question on The three-phase alternator, Get Answer, Expert's Help, The three-phase alternator Discussions

Write discussion on The three-phase alternator
Your posts are moderated
Related Questions
design a combinational ckt ,which detect whatever a no.(in binary) is divisable by 3 or 4

units of potential energy

Q. Explain Hexadecimal Number System? A Hexadecimal Number System: uses base 16 includes only the digits 0 through 9 and the letters A, B, C, D, E, and F In the Hexade

Q. (a) A balanced wye-connected load with per-phase impedance of 20 + j10 is connected to a balanced 415-V, three-phase supply through three conductors, each of which has a series

What do you understand by solid modeling and wireframe modeling in CAD systems? Explain and compare the both modellings. Describe the following 1. Boundary representation 2.

Magnetic permeability and the B/H curve To measure the relationship between field strength H and flux density B for a material, a sample is made into a closed ring and a magne

Q. What is the need of the resistance used in a clipper? Resistor is used in a clipper to limit the current through the diode. To avoid the damage due to excessive current thro

What is the use of stepper motor? A stepper motor is a device used to get an accurate position control of rotating shafts. A stepper motor employs rotation of its shaft in term

Q. Explain basic working of Ideal operational amplifier? The operational amplifier, known also as op amp, consists of several transistors, diodes, capacitors, and resistors. It

What do you mean by the term procedure? PROC: The PROC and ENDP directives specify the start and end of a procedure. Such directives force structure while the procedure is cle