The three-phase alternator, Electrical Engineering

Assignment Help:

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

 

 


Related Discussions:- The three-phase alternator

Determine the current in the series circuit, Q. (a) Let a unit impulse of v...

Q. (a) Let a unit impulse of voltage v(t) = δ(t) be applied to a series combination of R = 20 and L = 10 mH. Determine the current i(t)in the series circuit. (b) Repeat (a) for

Met, AC and DC distribution onboard ships

AC and DC distribution onboard ships

What is internal structure of 8086, 8086 is having 2 dissimilar units i.e. ...

8086 is having 2 dissimilar units i.e. BIU(Bus Interface Unit) and EU(Execution Unit), these two units work synchronously.

Define series var compensation, Define Series VAr Compensation? For ver...

Define Series VAr Compensation? For very long transmission lines, the inductive reactance of the line becomes so high that not much power can be transmitted through the line, s

Prepaid metering, Prepaid Metering Prepaid metering is the state of ar...

Prepaid Metering Prepaid metering is the state of art for single and three-phase although current metering, and should be implemented through utilities desirous of protecting

Management process of balanced score card, Management Process of Balanced S...

Management Process of Balanced Score Card The BSC (Balanced Score Card) proposes four a new management processes which separately and in combination, contributes to linking lo

Demagnetizing and cross magnetizing effects , Q.   What do you understand b...

Q.   What do you understand by demagnetizing and cross magnetizing effects of armature reaction in a d.c. machine. Derive the expression for calculation of demagnetizing and cross

Pu value, the p.u. reactance of a 25 MVA, 13.2 kV alternator 0.5 p.u. On a ...

the p.u. reactance of a 25 MVA, 13.2 kV alternator 0.5 p.u. On a base of 50 MVA and 13.8 KV the p.u. value shall be

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd