# 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, (YbYf).
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 pitchpole 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.