# Electrical Machine winding diagram(AC & DC) | Complete Winding Basics_Part-1 | (Subtitles included)

Hello everyone, in today’s topic, we we’ll see most unclear thing in electrical engineering, that is winding. There are

mainly two types of windings. One is Gramme ring winding, that is, will have a

ring like this, okay. This is a hollow ring and there are conductors, winding will be placed you know, this fashion. So throughout this this winding is given. I think we could see the picture there. Now another type of finding is drum type winding. Like, we will have a cylinder. Zoom.!

we will have a cylinder here. Now in these slots, conductors will be placed, like

winding will be given in this way. So it is distributed. Winding is distributed

here. So this is a drum type winding. So once the winding is done, now this will

look like this. Its wounded and we have commutator,

connections are there from here to commutator. Now we are splitting it here.

I just cut it here and spread it like this. So as you see, in the down side we

have commutator so this down end we’ll call it as, commutator end and this

commutator, from this commutator we will take the current or you know, will give

the current if it is a motor, so this end we can also say front end.

You can also say this commutator end as front end and this end is back end. Alright! so this is drum type winding. We

always use drum type winding. So our focus is now mainly on drum type winding. Next, second important aspect, number of turns, you know, we’ll go for winding like

this, let’s take this as a winding, okay. I am giving winding in this fashion. This

is one turn. I made one turn. This one turn is having how many conductors? Two conductors

and this number of turns is always an integer because we cannot have half a turn or a quarter turn like that. We’ll have some integer number, one two

three four like that. So if number of turns, that is, N is an

integer, one turn is having how many conductors? Yes! two conductors. So what

is relation between number of turns and number of conductors? Z=2N So if you multiply any integer with ‘2’ , we will get an even integer. I’m

multiplying any number, any integer number with ‘2’ , we will get the result is:

an even integer. So ‘Z’ is always an even integer, for any type of winding not

only DC machine AC machine, any type of winding for that matters, okay. So if I continue the winding, you know one coil is there. I am continuing winding like this. So here I’ll connect this point to commutator. Okay, this is connected to

commutator and winding is going further. So one commutator segment is connected

to how many conductors? Yes! 2 conductors, which means, what is the

relation between number of conductors and number of commutator segments? Yes! number of commutator segments=number of conductors / 2 (or) number of

commutator segments=number of turns, simply, alright!

Next one, what is pole pitch? Before going to that, let’s see, what is pitch? I think, if you’re aware of cricket, pitch in cricket is called what? yeah, distance between wickets, two wickets. So, how much is the distance? 22 Yards, very good.

So here, pole pitch means distance between two consecutive poles. Pole pitch means distance between two consecutive poles. So now, in case of cricket, we

measure that in terms of maybe Yards or meters, but here, how do you measure the

distance between two consecutive poles? Do we measure in terms of kilometers? or

meters or centimeters? No! we measure in terms of number of slots or maybe number of conductors. People may use anything. Okay, so how is it different from

measuring from number of slots or number of conductors? So if you see, anyways, we’ll discuss that little later. So what I’m saying is, pole pitch is the

distance between two consecutive poles, that can be measured either in terms of

number of slots or number of conductors. So I’m representing like this. ‘S’ Green is for number of slots, number of slots per pole or you may say, number of conductors per pole.

Both are right. Somebody may use this, some may use this. I prefer to use number of conductors, okay. Next one, this pole pitch, if you know the operation of DC generator,

this pole pitch is equal to 180 degrees, electrical. Okay, it’s always. One pole pitch

means 180 degrees electrical. From the operation, you can understand this. Just go through the operation of DC machine/ DC generator, you’ll get the point. Next one,

what is coil span or coil pitch? Where is a coil here? this is one coil. Alright!

This is one coil, what is the coil pitch? The distance between these two. You may

say, this is one conductor or this is a coil, so this is one coil side, this is another

coil side. So you may call it as a coil side or you may call it as conductor. So what is

the distance between these two? 1, 6. 6 – 1 is? Don’t get

confused here!! Distance between these two, in terms of slots means, don’t count

these slots!! 4 slots, so 4 is the distance? That’s wrong! Because if

somebody is asking you, what is the distance between 0 centimeters and

5 centimeters? what would you say? The distance is 5 centimeters. If

somebody is asking me, what is the distance between 1 centimeter and 5 centimeters? Then answer is, 4 centimeters. So here, distance between, the same terminology should be used here. Distance between 6th slot and 1st slot,

how much is that, in terms of slots? 5 slots! (6 – 1), simply, alright. So

that is coil span and this coil span, we should maintain this coil span, we should try to maintain this coil span to be close to 180 degrees. We should maintain coil span should be

equal to pole pitch. We should try to maintain, okay, for the better

addition of voltages, if it is a motor: for the better torque production, which

means, if this conductor is under the North pole, this conductor must be under the

influence of South pole and here, this must be under North Pole and this must be under South Pole. We should try to maintain that. But of course, it’s not

always possible. Next, what is the type of windings? So this winding, how this

winding is looking like? A wave shape. So this winding is called as wave

winding, simply. Because it is looking like a wave, it is called as wave winding. But

to make such a kind of winding, to make this structure, what are the details you require? I require this distance, back end distance. that is, what we’ll call it as

back pitch Yb, again the measurement can be in terms of number of slots or may be

number of conductors, okay. So how many number of conductors in between these

two? or how many number of slots in between these two? again, in between means, don’t count these!! just say (6 – 1), how much? Yeah, 5, okay. Next, we should

know this distance. What is this? Front end. So this distance is called as

front pitch. Alright! how much distance is that? 1, 2, 3, 4, 5 or (11 – 6) 11 – 6 is 5. Again this will be 5, again

next this will be 5. So if I have the information of back pitch and front pitch, you can understand, you can draw the winding. Are you clear? Next, another one is

called winding pitch. Okay, winding pitch is simply distance between

two consecutive coils. This is first coil and this is second coil. What is the distance between these two? This is the distance. (11 – 1), that is 10. Or else, you can say

(Yb – Yf) sorry, (Yb + Yf) is equal to winding pitch. I’m talking about wave

winding, okay. Now can you tell me from here? Yb, can it be a fractional

value? No, it can never be a fractional value. It is always an integer value, because it

is a count, number of slots. It is always an integer. Yf is also an integer.

It is always, always true. Okay, next one we have another pitch called average

pitch. What is the average pitch? simply, average of front pitch and back pitch.

That means, (Yb + Yf)/2. That’s it. Average of front pitch value and back pitch value. This is for any type of winding, it is true. Alright! it is true for wave

winding. Now, let’s go for another type of winding. So now instead of doing this, let me take this back in here.

I’m connecting these two commutator segments and there it has gone like this, means the

second coil is overlapped onto the first coil. Hence, we’ll call it as? Yes, lap

winding. So to draw the lap winding, what we require is a back pitch, it is already

there and front pitch, this value, okay. and this is front pitch. So these are the two types of

windings. Now, if you see here, I’m making coil like

this, in this fashion, coil I’m turning this way and winding also moving this way. Hence it is called as a progressive winding. Alright!

Now, what is a retrogressive winding? I think, I forgot to say winding pitch here.

What is winding pitch here? Distance between two consecutive coils. What is the distance between these two coils? This is a first coil and this is a

second coil and distance is (2 – 1), that is, 1. So, in case of lap winding,

winding pitch equal to (Yb – Yf). Alright! Now, the other? retrogressive

winding. Okay, now instead of keeping it here, what if I do after this first coil like

this? so, I’m turning coil in this direction but winding is moving

backwards, okay. So this is called as a retrogressive

winding. In case of retrogressive winding, Yb>sorry, (Yb

which means, you can understand now, why this winding pitch named as winding

pitch, okay. Because by looking at this winding pitch, we can say what type of

winding is that. Suppose, if winding pitch is negative, then we’ll call it as a

retrogressive winding. It is clear. If winding pitch is positive, then we’ll say

it has progressive winding. Of course, if this winding pitch

then it is wave winding. So this winding pitch is helping us or indicating the

type of winding. hence it is called so. There is another pitch called commutator

pitch. We’ll discuss that later. I hope, now progressive and retrogressive is clear.

Now what if I go for wave winding? In wave winding, what is progressive and what is retrogressive? Let’s see. So, wave winding, I’m continuing in this way, okay? So after this winding will go and it will continue here, okay? winding is continuing from here. Can you see? yeah. Means, after this winding, it has

started again after this. After the first one, it has started. So that is called as

progressive. What if, it would have started this side? yes, it is called as retrogressive winding. Are you clear? Very good. Now, Let’s find an interesting factor here. One important observation! So this is back

pitch and front pitch, so total this is? one winding pitch. okay and we have here back pitch, again

there will be a front pitch, that will carry you know somewhere over here maybe, so

this is a back bitch, another front pitch is here. So that will be giving us,

another winding pitch, till this. Now, tell me! what is (Yw1 + Yw2)? Again in terms of slots. You tell me in

terms of slots. If total number of slots are s, how many

slots are there, if I add these two? If I add these two, how many slots we get?Total number of slots are s, again it has started after the first one, so (s + 1),

green color means number of slots. Alright! Now, how many number of poles are here? 4 pole machine, I’m talking about 4 pole

machine, alright! So if it is a 6 pole machine,

then, if it’s a six pole machine, + Yw3.

you will get three things, three winding pitches, will be equal to (s + 1). Alright! Now, for retrogressive case: for retrogressive case,

it’ll not end here, (w1 + w2), w2 will be ended here itself. Alright!

So in case of retrogressive, this is simply -1.

I hope this is clear. Next what if I want, I want to represent the same, in terms of

number of conductors. Okay? Because some people do also represent in terms of conductors. So total number of conductors, in place of s, I am writing Z +/-.

+ is for progressive, – is for retrogressive winding and in place

of 1, yes, if it is if each slot is carrying one conductor, then this will be, yes simply 1. What if each slot is carrying 2 conductors? Then we’ll have

to keep 2. What if each slot is carrying 4 conductors, then it will be 4, like this. Here also same. s, sorry Z +/- 2. Okay? Now here, in

general, how can I write this? In general I can write this as (Yw*P/2).

Because we know these two are equal. How many are there? 2 are there, because we have 4 pole, that is, 2 pair of poles. If I have 3 pair of poles, that is, six poles;

then we have three terms. So in general, we are writing (Yw * pair of poles),

which is equal to either (s +/- 1) or (Z +/- 2). This is valid only if the number of conductors in each slot is 2. This is valid only if

number of conductors in each slot is 2. Because that is what we normally use.

That’s why, I am specifying that only. I hope now, you understand what is progressive, what is retrogressive, in case of lap and wave. Now, there is another thing

called singly reentrant and doubly reentrant or before we go to that, I

think we missed to see multiplex winding. Okay? So far, we have seen simplex winding. What is duplex winding? That’s interesting! Okay, so here what we’re done

after that, either I am continuing here right? So instead of putting it here, what

if I leave one slot? I left one slot, I’ll continue the windings. Then after one

complete cycle, then I’ll come to this, in continuation. So, what is the distance

between these two slots? (3 – 1) that is 2. Hence, we will call it as duplex winding. what if I use, or what if I skip three slots like this?

( 4 – 1) that is 3, triplex winding. If it is next, quadplex winding. Okay?

In case of lap, if I place it here, it is simplex winding. If I place it here, it is

duplex winding and this is triplex winding and quadplex something like that. Alright! Now, what is singly re-entrant,

doubly re-entrant? And this singly re-entrant and doubly re-entrant is there,

only for multiplex winding. Okay, so let me take duplex winding. This is duplex,

duplex lap. Doubly re-entrant means, I am going for winding. You know, duplex

winding is going like this and after all these things, it has ended here. It is

left over. There left, one slot is left in between and winding is ended here. Now, what I’ll do? I’ll place another set of winding, another fresh winding, another fresh wire I’ll take, I’ll start winding here. So, there will be two

independent winding sets will be there inside. That is what we’ll call it as

doubly re-entrant winding. What is singly re-entrant winding? So winding is going like this, but it is not ended here, it will continue here. Okay? After one

complete circle, left over slots will be continued. I hope now, these things are clear. What is the first one? Number of conductors is always

an even integer, number of commutator segments is equal to number of coils.

Okay, and back pitch and front pitch, they are always an integer. Alright!

Progressive winding, retrogressive winding; that is clear. Simplex, duplex and

singly re-entrant, douby re-entrant. So now, one thing is left. That is, double layer

winding. What is single layer winding? What is double layer winding? double layer

winding means, there are two layers. Don’t think that each slot is having two

conductors, then only it is double layer. No, it’s just 2 layers, maybe 4 conductors, 2 are on the upper layer, 2 are on the bottom layer, that is also a

double layer. 4 conductors per slot, but it is a double layer. Alright! Even

2 conductors, they’re placed in 2 layers, that is also a double layer. If

only 1 conductor is there or maybe 2 conductors are placed side by side,

that is also single layer. I hope now, you understand what is double layer and what is single layer. We normally use double layer winding, double layer only, we

frequently use and duplex winding. But throughout our analysis, we look at, maybe further lectures also, we look at double layer, simplex windings only. Okay? Thank you for watching. Please like the video and share your comments. Don’t forget to subscribe to our channel for more such videos. Thank you.