Skip to main content

Construction of 3-Phase Alternator

Construction of 3-Phase Alternator

A 3-Phase alternator has 3-stage winding on the stator and a d.c. the field winding on the rotor.

Construction of 3-Phase Alternator


1. Stator

  • It is the stationary piece of the machine and is developed of sheet-steel overlays having openings on its inward outskirts.
  • A 3-stage winding is put in these spaces and fills in as the armature winding of the alternator.
  • The armature winding is constantly associated star and the unbiased is associated with the ground.

2. Rotor

  • The rotor conveys a field winding which is provided with direct current through two slip rings by a different d.c. source.
  • This d.c. source (called exciter) is commonly a little d.c. shunt or compound generator mounted on the pole of the alternator.


Rotor development is of two types, to be specific ;

(1) Salient (or anticipating) post type

(2)  Non- Salient (or cylindrical) shaft type

(1) Salient post type

  • In this sort, remarkable or anticipating poles are mounted on an expansive round steel outline which is fixed to the pole of the alternator as appeared in Fig. 22.2.
  • The individual field pole windings are associated in an arrangement so that when the field winding is invigorated by the d.c. exciter, adjoining poles have inverse polarities.


Slow and medium-speed alternators (120-400 r.p.m, for example, those determined by diesel motors or water turbines have remarkable post-type rotors because of the accompanying reasons :

(a) The notable field poles would cause an over-the-top windage misfortune whenever driven fast and would will in general produce noise.
(b) Salient-shaft development can't be made sufficiently able to withstand the mechanical worries to which they might be oppressed at higher speeds.

  • Since a recurrence of 50 Hz is required, we should utilize a large number of poles on the rotor of moderate-speed alternators.
  • Low-speed rotors dependably have a huge measurement to give the fundamental space to the poles.
  • Thus, notable post-type rotors have substantial breadths and short pivotal lengths.

(ii) Non-salient type

  • In this sort, the rotor is made of a smooth strong produced steel outspread chamber having various spaces along the external outskirts.
  • The field windings are installed in these spaces and are associated in arrangement with the slip rings through which they are invigorated by the d.c. exciter.
  • The areas shaping the poles are generally left un-slotted as appeared in Fig. 22.3.
  • Unmistakably the poles framed circular segment non-notable i.e., they don't extend out from the rotor surface.

High-speed alternators (1500 or 3000 r.p.m.) are driven by steam turbines and use non-striking sort rotors because of the accompanying reasons :

(a) This kind of development has mechanical heartiness and gives the silent task at high speeds.
(b) The transition conveyance around the fringe is about a sine wave and subsequently a superior e.m.f. the waveform is gotten than on account of remarkable shaft type.

  • Since steam turbines keep running fast and a recurrence of 50 Hz is required, we need a few poles on the rotor of rapid alternators (additionally called turboalternator).
  • We can utilize no under 2 poles and this fixes the most astounding conceivable speed.
  • For a recurrence of 50 Hz, it is 3000 r.p.m. The following lower speed is 1500 r.p.m. for a 4-shaft machine.
  • Subsequently, the turboalternator has 2 or 4 poles and has Small breadths and long pivotal lengths.

Popular posts from this blog

RS Aggarwal Aptitude Book PDF Free Download

RS Aggarwal Aptitude Book PDF Free Download RS Agarwal Aptitude Book PDF Free Download: Quantitative Aptitude by R.S Aggarwal is a standout amongst the most inclining books among the hopefuls getting ready for Bank PO, PO, MBA, RBI, IBPS, CAT, SSC, IAS, PSC, Hotel Management, Railway Recruitment Exams, and other aggressive and placement tests. This book is suggested by different specialists in this field. This book covers relatively every theme which is being requested for the focused exams. On the off chance that you are looking to Download RS Aggarwal Quantitative Aptitude PDF's most recent version with the expectation of complimentary then you appear to be at the correct place.    Download PDF  RS Agarwal Aptitude Book PDF Free Download This book covers Problems on Surds and Indices, Simplification, Numbers and Ages, Pipes and Cisterns, Boats and Streams, Problems on Trains, Simple and Compound Interests, Time and Work, Permutations and Combination, Clocks, Odd Man Out, Heights
Read more

Limitations of Terzaghi Theory

Limitations of Terzaghi Theory The value of the coefficient of consolidation has been assumed to be constant.  The distance d of the drainage path cannot be measured accurately in the field. The thickness of the deposit is generally variable, and an average value has to be estimated.  There is sometimes difficulty 1n locating the drainage face, and sometimes thin previous seams that can act as good drainage faces are missed in the boring operations. The equation is based on the assumption that the consolidation is one-dimensional. In the field, the consolidation is generally 3-dimensional. The lateral drainage may have a significant effect on the time rate of consolidation. The initial consolidation and secondary consolidation have been neglected. Sometimes these form an important part of the total consolidation. In actual practice, the pressure distribution may be far from linear or uniform.
Read more

Comparison between VSI and CSI

Comparison between VSI and CSI In power electronic systems, inverters are an essential component that converts direct current (DC) into alternating current (AC). There are two main types of inverters used in power electronic systems: Voltage Source Inverters (VSI) and Current Source Inverters (CSI). Both have their own unique advantages and disadvantages, and the choice of which to use depends on the specific application and the desired outcome. Comparisons between voltage source inverters and current source inverters are as follows. In voltage source inverters, the input voltage is maintained constant and the amplitude of the output voltage does not depend on the load. However, the waveform of load current, as well as its magnitude, depends upon the nature of load impedance.  In current source inverters (CSI), the input current is constant but adjustable. The amplitude of output current from CSI is freelance of the load. However, the magnitude of output voltage and its undulation outp
Read more