Construction Of Alternator Pdf

This particular phenomenon results in three phase power flow out of the alternator which is then transmitted to the distribution stations for domestic and industrial uses. The term salient means protruding or projecting. The working principle of alternator is very simple.

Rather, the central polar area is provided with slots for housing the field windings as we can see from the diagram above. So, we have seen how an alternating current is produced in a turn is rotated inside a magnetic field. As per this rule the direction of this current will be from A to B.

It shows that, the direction of the current changes after half of the time period, that means we get an alternating current. To prevent these oscillations from going beyond bounds the damper winding is provided in the pole faces as shown in the figure. The field coils are so arranged around these poles that flux density is maximum on the polar central line and gradually falls away as we move out towards the periphery. The cylindrical rotor type machine gives better balance and quieter-operation along with lesser windage losses. The stator core is made up of lamination of steel alloys or magnetic iron, to minimize the eddy current losses.

In this case, the direction of the induced current according to Fleming's right hand rule will be along D-C-B-A. Recieve free updates Via Email! The cylindrical rotor type machine has a uniform length in all directions, giving a cylindrical shape to the rotor thus providing uniform flux cutting in all directions.

The rotor rotates in the stator, game of thrones book 3 pdf free and the field poles get projected onto the rotor body of the alternator. Alternating current generators or alternators as they are more popularly known are work on the principle of electromagnetic induction and consist of a stationery armature and a rotating field rotor. This relative difference will induce the current in them which will exert a torque on the field poles in such a way as to bring the alternator back to synchronous speed operation.

Construction of Alternator

The recent trends towards such stator construction are more in favour of using mild steel plates which are welded together rather than using castings. In the next couple of articles we will take a brief look at alternator construction studying its different parts one by one and learning about their construction starting with alternator stators. The figures below show images related to stator assembly and the arrangement of coils etc Stator Construction.

In this way, the current completes one full sine wave cycle during each o revolution of the turn. The salient pole type of rotor is generally used for slow speed machines having large diameters and relatively small axial lengths.

Stator Construction

The core is constructed in the form of laminations and the material used for the same is either magnetic iron or steel alloy. This is our elementary model of alternator. If we connect two terminals of an external load with these two brushes, we will get an alternating current in the load.

Instead, the stator is used for holding armature winding. So if the turn continues to rotate the current in turn continually alternate its direction. The construction of an alternator consists of field poles placed on the rotating fixture of the machine. The armature conductors are housed on the stator. Newer Post Older Post Home.

There are different types of armature slots provided in the core to insert the conductors and the three various types are as follows. The coil is connected to slip rings, and the load is connected through brushes resting on the slip rings. Thirdly apart from insulation it is also easier to brace these windings to prevent any deformation. If the close path is provided to the conductor, induced emf causes current to flow in the circuit.

Now we place one stationary brush on each slip ring. Home Electrical machines Power system Contact electricaleasy. To enable that, the mechanical input given to the machine in terms of rotating torque must also be very high.

Stator Construction

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Construction of Alternator

An alternator as mentioned earlier is mostly responsible for generation of very high electrical power. As at this position the turn comes at horizontal position from its vertical position, the current in the conductors comes to its maximum value from zero. The damper windings are basically copper bars short-circuited at both ends are placed in the holes made in the pole axis. While the turn further proceeds to its vertical position the current is again reduced to zero. The direction of magnetic flux will be form N pole to S pole.

Working Principle of Alternator

That means current is circulating in the close turn from point B to A, from A to D, from D to C and from C to B, provided the loop is closed although it is not shown here. The rotor, in this case, consists of a smooth solid steel cylinder, having a number of slots along its outer periphery for hosting the field coils. From this, we will now come to the actual working principle of an alternator. Now, see the above figure.

But as soon as it departs from the synchronous speed there will be relative motion between the damper winding and the main field which is always rotating at synchronous speed. Salient pole alternators driven by water turbines are called hydro-alternators or hydro generators. But, the unlike other machines, in most of the alternators, field exciters are rotating and the armature coil is stationary. This article is about alternator. Whereas the wide open slots are easier from the winding and repair perspective, they are also having a disadvantage that improper distribution of air gap flux.