Winding

WINDINGS

Winding consists of

1. Conductors or wires

When these coils are connected in series or parallel then winding is formed

2. Turns

3. Coils 1 2 3

1 2 3

series Parallel

Insulator

conductor

WINDINGS

The windings in rotating electrical machine can be be classified as

a) Concentrated windingb) Distributed winding

a) Concentrated winding:Turns have SAME magnetic axisWdg turns are wound together.One multi-turn coil

For example, primary and secondary wdg of transformer

primary secondary

ΦMagnetic axis



primary secondary

Top view of wdg



primary secondary

If wdg is cut, vartically, conductors can be viewed

Top view of wdg

Another example is of field wdg of DC machines

For this wdg first former is made with insulation



Φ



Φ

Earth's Magnetic Field

Ear

thM

agne

t

N

S

SN

Compass

Pole

Flux Path through rotor and stator core

Pole


Pole

Now if the pole is cut, the front view will beas shown below


Pole


Flux waveformFlat Topped

44


Pole


Flux waveformFlat Topped

443322

11

Sinusoidal


ROTOR

STATOR

Φ

b) Distributed winding:The wdg turns are arranged in several FULL- PITCHor fractional-pitch coils.The coil are housed in the slots spread around theair gap periphery to form phase or commutator wdg.

For exampleStator and rotor of Induction machinesThe armature of synchronous machines

The armature of DC machines

Stator core or Stamping

SlotTooth


SlotAir gap

Rotor

Shaft

Tooth

Rotor

Shaft


SlotAir gap

Conductors

Insulator

Tooth

b) Distributed winding:Armature Winding is again classified as

a) Closed Windingb) Open Winding

a) Closed Winding meansIf one starts from any point on the wdg and traverses it, one again reaches the same starting point For example commutator wdg in AC and DC m/cs

Shaft

Commutator

Insulation

Brush

Conductor

For example commutator wdg in AC and DC m/cs

b) Distributed winding:Armature Winding is again classified as

a) Closed Windingb) Open Winding

a) Closed Winding meansIf one starts from any point on the wdg and traverses it, one again reaches the same starting point

Shaft

Commutator Armature Core

Armature WdgInsulation

BrushDue to commutation action, wdg is shorted & closed

Conductor

CommutatorCommutator

The open wdg terminates at another point or terminal orslip rings. For example, star wdg

The delta wdg is a closed wdg, can be made openby making reconnection in star

R2

R1

Y2

Y1

B2

B1

Shaft

Slip Rings

SlipRings

But commutator wdg in no case, can be open circuited.

Some common terms used in wdg are described below:

1. Turn: One turn consists of TWO conductors, T=2 Z

A

B

C

D

E

Conductor AB and Conductor DE

BCD is called as OVERHANG.This portion is outside the core

CORE

Overhang

terminalsStart Finish

A

B

C

D

E

Conductor AB and Conductor DE

A

B

C

D

E

One coil may consists of 1 turn ie one turn coil,2 turns,

Overhang

3 turns, N turns or Multi-turn

A

B

C

D

E

A multi-turn coil is one which has more than one turn

1. Turn: One turn consists of TWO conductors

Start Finishterminals

A

B

C

D

E A

B

C

D

E

Overhang

Coil SidesCoil sides

A

B

C

D

E

2. Coil Sides:AB and DE are called as Coil Sides of a coil

T=2 CS Conductors in One coil side = No of turnsTwo turn coil = four coil sides One coil side = 2 Z=2T

Start Finishterminals

3. Layer Winding:If one coil side occupies the total SLOT area, then it is called as Single Layer Winding.

If the slot contains even number of coil sides, then the winding is called as Double Layer Winding.

Two coil sides per slot

Four coil sides per slot

Top coil sides

Bottom coil sides

are numbered ODD1 3 5 7

are numbered EVEN2 4 6 8

(Top Layer)

(Bottom Layer)

3. Layer Winding:

Double layer wdg has one side in the top layer andother side in the bottom layer.In the drawing the top coil side is shown by a SOLID line and bottom coil side is shown by a DOTTED line.

Top coil side Bottom coil side 1 8

3. Layer Winding:Single layer wdg is used in small machines upto 5kW.Double layer wdg is used in m/cs above 5kW.

Advantages of double layer wdg over single layer wdg:1. More economical2. Easier to house in slots during repair3. Lower leakage reactance4. Better performance5. Better emf waveform in case of generator

4. Pole Pitch:

The peripheral distance between two adjacent polesis called pole pitch.

Pitch indicates a particular method of measurement.

Pole pitch is always expressed in electrical degrees.

The flux under pole is

1800 π radians Electrical

Pole pitch is also expressed in terms of coil sides and .

teeth.

Pole Pitch

Two Pole Machine

1800 electrical =1800

Mechanical

Pole Pitch

Pole Pitch

Four Pole Machine

Pole Pitch

Total elect. angle=7200 elect

Total mech. angle

=3600 mech

E=MP, P=pole pairs

Pol

e P

itch

Pole Pitch

Two Pole Machine

1800 electricalP

ole

Pitc

h =1800 Mechanical

Pole Pitch Pole Pitch

Pole Pitch

Four Pole Machine

1800 electrical =450 Mechanical

5. Coil Span or Coil Pitch:The distance between two coil sides of a coil is calledas coil span or coil pitch.It is usually measured in terms of teeth, slot or electricaldegrees.

Coi

l sid

e

Coi

l sid

e

Coil Span

If supply is given to end terminals, the current direction is as shown in fig.

Suppose upward direction of current produces N pole

N S

Then downward direction of current will produce S pole

Pole pitch

If coil span is equal to pole pitch, then the coil is called as FULL-Pitched coil

5. Coil Span or Coil Pitch:

Coi

l sid

e

Coi

l sid

e

Coil Span

N SPole pitch

If coil span is less than pole pitch, then the coil is called

FULL-Pitched coil

Coil Pitch

N SPolepitch

Short-Pitched coil

as Chorded, Short-Pitched or Fractional–Pitch coilThe coil pitch is rarely greater than pole pitch.

electricalPoleperSlots

1800

elect1800 0306

6. Slot Angular Pitch:The peripheral distance between two adjacent slots,is called slot angular pitch.

Slot angular pitch is always expressed in elect. degrees.Slot angular pitch is given by gamma

If total no of slots = 12, Poles = 2,

γ =30

0

γ =3

00then S/P=6

1 23

4

5678

9

10

1112

If coil pitch=S/P, then it results

If coil pitch < S/P, then it results in Short Pitch Wdgin Full Pitch Winding

Distributed winding:Armature Winding

Closed WindingIf one starts from any point on the wdg and traverses it, one again reaches the same starting point Used all types of DC m/cs and AC commutator m/csClosed type wdg is always double layer wdg.

Simple closed type wdgs are of two types1. Simplex Lap Wdg1. Simplex Wave Wdg

This types depends on the manner of connections to thecommutator segments.

1. Simplex Lap Wdg 1st 2nd 3rd 4th In race, what is

it called?

LAP

So this is the shape of LAP wdg


it called?

LAP


Top

coil

side

Bot

tom

coi

l sid

e

1 8

1. Simplex Lap Wdg

Top

coil

side

Bot

tom

coi

l sid

e

1 8

Single Multi-Turn Lap Coil

Commutator 1 2 3 4 5

Conductor Insulator

Coil 1Coil 1

Start 1

Finish 2

Commutator segment

Movement of lap

first to forward

then to backward

1. Simplex Lap Wdg

1 8

3 Multi-Turn Lap Coils

Commutator

Conductor Insulator

Coil 1

3 10

Coil 1

Start 1

Finish 2

Commutator segment

Coil 2

Coil 2

Start -2Finish -3

Coil 3

Coil 3

Start -3Finish -4

Commutator segment 2

Bottom side of coil 1

5 12

1 2 3 4 5

& top side of coil 2

are connected

1. Simplex Lap Wdg

1 8

3 Multi-Turn Lap Coils

Commutator

Conductor Insulator

Coil 1

3 10

Coil 1

Start 1

Finish 2

Commutator segment

Coil 2

Coil 2

Start -2Finish -3

Coil 3

Coil 3

Start -3Finish -4

Commutator segment 2

5 12

1 2 3 4 5

Bottom side of coil 1

& top side of coil 2

are connected

2. Simplex Wave WdgThis movement is similar to wave



TATA


2. Simplex Wave Wdg

Wave wdg - Single turn coil

1 10 17 26

N S N S

Coil 1 Coil 2

CommutatorConductor Insulator

1 11 213600

1800

3600

Start of coil 1is bent towardsLeft wrt lap wdgFinish of coil 1is bent towardsright

Movement ofwave wdg

is onlyforward

2. Simplex Wave Wdg

Wave wdg – -turn coil

1 10 17 26

N S N S

Coil 1 Coil 2


1 11 213600

1800

3600


Movement ofwave wdg

is onlyforward

MULTI

2. Simplex Wave Wdg

Wave wdg – -turn coil

1 10 17 26

N S N S

Coil 1 Coil 2


1 11 213600

1800

3600


Movement ofwave wdg

is onlyforward

MULTI

Have U followed?or shall I move like wave?

O K

7. Back Pitch:The distance between top and bottom coil sides of one,coil is called back pitch, symbol yb.

It is measured at the back of the armatureFirst comes TOP side, second comes BOTTOM sideYou have to see from bottom to top for measurementThat’s why the name BACK

It may be expressed in terms of slots, teeth or coil sides

1 8

Coil 1

3 10

Coil 2Coil 3

5 12

1 2 3 4 5

For lap wdg, for coil 1yb=8-1=7

yb

For coil 2, yb=10-3=7For coil 3, yb=12-5=7

7. Back Pitch:The distance between top and bottom coil sides of one,coil is called back pitch, symbol yb.

It is measured at the back of the armatureIt may be expressed in terms of slots, teeth or coil sides

For wave wdg, for coil 1

yb=10-1=9

For coil 2,

yb=26-17=9 1 10 17 26

N S N S

Coil 1 Coil 2

1 11 213600

1800

3600

yb yb

Thus the back pitch is

Always ODD

8. Front Pitch:The distance between two coil sides connected to thesame commutator segment is called front pitch, symbol yf.

Stand on commutator segment, raise your hand and seetowards front side.

1 8

Coil 1

3 10

Coil 2Coil 3

5 12

1 2 3 4 5

yf

You will see bottom side of coil 1and top side of coil 2

For commutator segment 2yf =8-3=5

For commutator segment 3yf =10-5=5

Consider lap wdg

8. Front Pitch:

yf

For commutator segment 11

yf =17-10=7

Front Pitch yf is always ODD number

Consider wave wdg

1 10 17 26

N S N S

Coil 1 Coil 2

1 11 213600

1800

3600

9. Winding Pitch:The distance between two consecutive and similar topor bottom coil sides, as the winding progress is called the winding pitch, symbol yw.

It is expressed in terms of coil-sides.

1 8

Coil 1

3 10

Coil 2Coil 3

5 12

1 2 3 4 5

yw

For lap wdg the consecutive and similar top coil sides

similar bottom coil sides are numbered 8, 10, 12 yw

Therefore, wdg pitch yw=3-1=2yw=5-3=2 =10-8=2 =12-10=2;

are numbered 1, 3, 5 or

yw= yb - yf

yb

yfTherefore, for lap wdg

9. Winding Pitch:

yw

Consider wave wdg

1 10 17 26

N S N S

Coil 1 Coil 2

1 11 213600

1800

3600

The consecutive and similar top coil sides are numbered or similar bottom coil sides are numbered 10, 26

Therefore, wdg pitch yw=17-1=16

yw=26-10= 16

1, 17

ywyw= yb + yf

yb

yf

Therefore, for wave wdg


Have U followed?or shall I move like wave

1. Simplex Wave Wdg

1. Simplex Wave WdgThis types depends on the manner of connections to thecommutator segments.

1 8

1. Simplex Lap Wdg


it called?

LAP


2. Simplex Wave Wdg 1st 2nd 3rd 4th In race, what is

it called?

LAP



it called?

LAP


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Winding