DC machine Part -2

far wide applications. So it is DC machines have a lot of control and because of this they find large number of applications. Wherever you require a quick response, so wherever. 300 change of torque and speed we use the same machines so to sum up.

Please find them still in large number of applications where ever you require a quick response wherever required sudden changes in torque and speed and also continuous change that takes place for motoring operations. So in view of these very important advantages, we find DC machines in automotive electronics,. So you find the costumes the supply in an in a automotive.

electric vehicle are a normal road vehicle or a car is battery. We find large number of DC machines in electric in automatic electrics. We find them in mining where considerable amount of speed control is required for several Drive applications. We find them in earth-moving equipment. We find them in still rolling Mills and aluminium rolling bills. That means metallurgical applications because it

require change of speed then we also use them in robotics for quick response for for movement of several parts, and they are still extensively uses electric traction or electric trains. The DC machines are being used. Then they they are used in lifts and highest and you find them in entertainment Electronics like your audios video system, wherever you require a movement of the drives, they are all using DC machines supplied power through the batteries are from a DC source.

We also find them extensively in computers this small DC machines for either variable speed operation or a fixed speed of pressure. So we find that these machines still have very wide applications. typically power 4 adjustable speed drives. Okay now we having learned broadly historically what it is about what are the functions of this machine speciality of Risa machines and typical uses of DC machines. We can go further into how do they look like and how they are made and after that we can know more about its internal working principles and so on so

Recalling. We will continuously be using certain terminologies as in any electrical machine. So we use for example the terminology in electrical machines. We use State arrest History part rotor rotating part and the air gap which is the space between the stator and rotor and we also use the terminology called a frame and you Oak frame or the yolk is the one which carries the stator are the stator is fixed inside the frame of the yolk and we use the terminology called decor and whining. The core is the one which part carries the magnetic flux and winding is a one which carries the electric current. Okay, and there are several types of windings which are used in in electrical machines. They are Lumpur winding concentrated winding distributed winding.

concentrate curve overlap windings and so on there are single are winding double are widening. So there are different types of windings when we discuss about Armature windings. We will know about this so the windings are in all machines. You can say you take copper wires make turns and have certain number of turns to make a coil and interconnect the coils to make the windings. So that is the the sequence of providing the electrical winding component in an electrical machine now we also have continuous the use the term Armature and field they are mature is a part which is producing power whereas a field is a part which is producing flux in all the electrical machines. We require a flux producing component and the power producing component because in some there could be some intermixing of the two but in geese emissions they are fairly

structure that there is a separate our culture, which is rotating and a separate field which is stationary. Okay. We also continuously use a terminology. Called motoring than generating. Okay, so the Motoring.

operation in the generate in operation information in Motoring it is taking electrical power giving out mechanical Power and generating. It is taking mechanical Power and giving out electrical power if you want to be a little more elaborate, this is a motoring operation. There is a motor which takes electrical energy and also supplies the molecular energy losses and remaining goes

mechanical energy. So this is the motoring convention then on the other hand if it is a generating. this generator takes mechanical energy. It also supplies losses energy losses, and then it gives out electrical energy. And so this is DC machines also will will work both in the motoring and generating boards. So for we identify that any machine must have an electrical

ordered a mechanical Port that means mechanical Port is a shaft through which either you can take out mechanical energy are put in mechanical energy. Are you have an electrical Port basically their electrical terminals which are in the machines through which you can pass a current or take out a current. Okay, apply a voltage. age are take out the voltage as in a generator.

We also of course the in general we use accessing the rotor we use to mechanism one is called a slip ring Arrangement under is called a commutator segments because you require a brush stationary brush in either case in a DC machine we use a commutator arrangement in which we have a brush through which you apply a

The Liturgy I’ll take out electrical energy and this commutator converts the frequency from DC to AC and vice versa.

What is DC Machine Part -1

a comprehensive idea on important engineering aspects of DC machines, which are all the important electromechanical devices being used in several applications. Now the we should know what is a DC machine. the DC machines are basically the machines. Which are operated with DC Supply?

That is why they are called the DC machines. now how important they are historically. Historically they are been they have been in use for a very long period it is because the first man-made source of electricity is a battery. So battery is a source a DC source and

in view of this constraint first machines which were developed for DC machines because they were the machines which were operated with DC Supply. Okay. So in a nutshell we have we realized that these DC machines these emissions for the first in use for energy conversion. Okay?

so the importance is that these have been in use for a longest period of time in history this DC machines. now having seen that they have a long history. we should so what is special about these machines? there is one important part.

There is one Central and versatile part in a DC machine, which makes it special and also for several applications now that part is called a commutator. Which distinguishes US from other machines it is mainly in the DC machine that we find this part called a commutator. We will learn about it little later. Now this commutator was invented by

two scientists one pixie 1832 and Richie in 1833. This is a device a part aA commutator which was in which we can say is primarily a mechanical converter inverter system, which has a capacity to change the frequency of the currents. That means we can make AC to DC and DC to AC DC.

to the precious will convert to a see inside the windings are AC instead reminding will Rectify to DC at the precious? now it was Thomas Alva Edison. Who use DC generators and the the First Central Power Plant was developed by Thomas Edison for New York by using DC generator. And so if you look historically the first Power generating plant for New York was using DC generators, and this was developed by well-known scientist. Come engineer Thomas Alva, Edison.

No, what is the present status? the present status is that there are other machines primarily AC machines. But they’re competing with the DC machines. However in spite of competing demand obviously machines these DC machines they still account for about 35 percent of monetary value of electrical machines production in the world the means if you look at that so much of amount monetary value if it is hundred thirty five percent of the monetary value is for the DC machines.

Although you summations are competing. However, it is interesting to note. That cost per kilowatt of a DC machine is among the highest compared to other missions. So this is also a factor we should know note that the cost per kilowatt of is highest. Why is it highest there is is because these machines are having complex construction compared to say AC machines now the DC machines can work either as a motor generator now the DC generators are finding reduced use because if you want a DC Supply, you can always get it from the AC Supply by using electronic rectifiers with the diodes high-powered efforts being available one can always have

five units built and you can Rectify it so that DC Supply can be easily obtained to rectify. So DC generator are finding produced use but how our DC motor still dominate because of flexible torque and speed control to find that both torque and speed can be very easily controlled in the case of DC machines. Okay, that is one of the great strengths of the DC Machines of independent or computer controls. So they continue to be used for variable speed. motor operations

it is having n flexible field and current control due to the commutator and this