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INTRODUCTION DC ARMATURE WINDING AC MACHINE WINDING

EE09 605 ELECTRICAL ENGINEERING DRAWING

Akhil A. Balakrishnan1

1Department of Electrical & Electronics EngineeringJyothi Engineering College, Cheruthuruthy

As on January 12, 2014

Akhil A. Balakrishnan (JECC) Lecture Notes As on January 12, 2014 1 / 44

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We will go through...

1 INTRODUCTION

2 DC ARMATURE WINDING

3 AC MACHINE WINDING





OBJECTIVES

*To make students to be able to plan and draw different views of electricalmachines and transformers.

*To make the students to draw different types of windings used inelectrical machines.

*Introduction to AutoCAD in Electrical engineering drawing.





SYLLABUS

Module I (12 Hours)DC Windings: Simplex lap and wave dc armature windings.AC Windings: Mush and concentric type single layer three phase acarmature windings. Simplex lap and wave, integral and fractional slot,double layer three phase ac armature windings.Introduction to AutoCad:Developed winding diagrams (Auto Cad notincluded for Examination).





SYLLABUSModule II (14 Hours)

1 Sectional plan and elevation of a transformer limb with windings.2 Sectional plan and elevation of the core assembly of a power

transformer.3 Sectional plan and elevation of a distribution transformer tank with

its accessories.4 Sketches of capacitor and oil filled type transformer bushings.5 Layout and single line diagram of a distribution transformer.

Substation Layouts:1 Layouts and single line diagrams of outdoor and indoor substations.2 Layout of a 220KV substation.3 Layout of a captive power substation.4 Single line diagram of a distribution centre.





SYLLABUSModule III (26 Hours)DC Machines:

1 Sectional front and side elevation of armature with commutator of adc machine.

2 Sectional front and side elevation of the yoke and pole assemblywith field winding of a dc machine.

3 Sectional front and side elevation of an assembled dc Machine.Alternators:

1 Sectional front and side elevation of a water wheel rotor assemblywith winding.

2 Sectional front and side elevation of a salient pole alternator.3 Sectional front and side elevation of a Turbo alternator.4 Sketches of the methods of pole fixing and slot details of Turbo and

Water wheel alternator.Akhil A. Balakrishnan (JECC) Lecture Notes As on January 12, 2014 6 / 44




REFERENCESText Books

1 Narang K. L., A text book of Electrical Engineering Drawing, TechIndia Publications

2 C. R. Dargan, Electrical Drawing and Estimation, New AsianPublishers

Reference Books1 Bhattacharya S. K., Electrical Engineering Drawing, Wiley Eastern.2 Clayton and Hancock, Performance and design of dc machines,

ELBS.3 Sawhney, Electrical Machine Design, Dhanpath Rai & Sons.4 Say M.G, Performance and design of AC machines, Pitman, ELBS.5 A. Nagoorkani, A simplified text in Electrical Machine Design, RBA

Publications





Internal Continuous Assessment (Maximum Marks - 30)30% - Tests60% - Assignments such as class work, home work10% - Regularity in the class

University Examination PatternQ I - 2 questions A and B of 15 marks from Module I with choice to

answer any one.Q II - 2 questions A and B of 20 marks from Module II with choice to

answer any one.Q III - 2 questions of 35 marks from Module III with choice to answer

any one





DC ARMATURE WINDING

Armature Winding: Consists of number of coils connected in seriesand number of such series circuits are connected in parallel.DC machine armature are double layer windings, which meansthat each slot has two coil sides.Two types of double layer winding areSimplex Lap winding• Finish of a coil is connected to start of next coil.• No: of parallel paths = No: of poles

Simplex Wave winding• Finish of a coil is connected to start of a coil which is lying one pole

pitch away from the finish.• No: of parallel paths = 2

Ends of the coils are connected to commutators.





DC MACHINE WINDING





ELEMENTS OF AN ARMATURE WINDING

Conductor: Active length of copper or aluminium wire in the slot.Turn: Two conductors connected to an end by an end connector.• Two conductors of a turn are placed approximately a pole pitch

apart.





ELEMENTS OF AN ARMATURE WINDINGCoil Side: Active portions of the conductors in a coil.• A coil have two sides.

Upper (Top) coil side and Lower (Bottom) coil side.• Distance between two coil sides is approximately kept as one pole

pitch.Overhang: End portion of the coil connecting the two coil sides.Coil Span: Distance between two coil sides of a coil.• Expressed in terms of number of slots or in electrical degrees.





ELEMENTS OF AN ARMATURE WINDINGCoil : Several turns connected in series.• Principal element of armature winding.• Coil with single turn is called single turn coil and with several turns

is called multi turn coil.

Single Turn Coil







Two Turn Coil







Three Turn Coil






Winding: Several coils connected in series.






Pole Pitch: Peripheral distance between center of two adjacentpoles in dc machine.• Angle between centers of adjacent poles is 180◦ (electrical).





ELEMENTS OF AN ARMATURE WINDINGFull pitched coil: Coil span is equal to pole pitch.Short pitched or chorded coil: Coil span is less than the polepitch.Single layer winding: Coil sides are arranged in a single layer in aslot.Double layer winding: Coil sides are arranged in two layers in aslot.





IMPORTANT TERMS RELATED TO WINDINGBack pitch(Yb): Distance between top and bottom coil sides of acoil measured around the back of armature.• Always an odd number.• Determines size of the coil (coil span)• Equal to coil sides per pole or pole pitch.

Front pitch(Yf ): Distance between two coil sides connected to thesame commutator segment.Winding pitch(Y): Distance between the starts of two consecutivecoils measured in terms of coil sides.• Always an even integer.• Y = Yb - Yf for lap winding• Y = Yb + Yf for wave winding

Commutator pitch(Yc): Distance between two commutatorsegments to which the ends (start & finish) of a coil are connected.• Measured in terms of commutator segments.





LAP WINDING

Yb = 2C/P ± KY = Yb - Yf

Y = ± 2 (Simplex)Yc = Y/2 = ± 1 (Simplex)

Yf = Yb - YA = P

K = integer or fractionBack end : 1 + Yb = X1Front end : X1 - Yf = X2





WAVE WINDING

Yb = 2C/P ± KY = Yb + Yf

Y = (2C ± 2)/(P/2)Yc = Y/2 = (C ± 1)/(P/2)

Yf = Y - YbA = 2

K = integer or fractionBack end : 1 + Yb = X1

Front end : X1 + Yf = X2





TYPES OF WINDINGProgressive Winding: Winding progresses in the direction of thecoils are wound.Retrogressive Winding: After passing once round the armature,the winding falls in a slot to the left of its starting point.

Progressive Winding Retrogressive Winding





EQUALISER RING

In Lap winding, the EMF’s induced in each parallel path may not beexactly equal.It results in internal circulating currents in the armature circuit andin the brushes.Causes : Excessive heating, sparking at the brushes and mechanicalvibration.To overcome this, Equaliser rings are provided at the back of thearmature.No of equaliser rings, m = Z

2PNo of tappings to one equaliser ring = No of pair of poles(P/2)Distance between adjacent tappings = No of coils

No of tappings = 2CmP





DESIGN OF WINDINGNo of slots = SNo: of conductors or coil sides = ZNo: of coils,C = Z/2No of commutator segments = No: of coilsNo: of poles = PNo: of parallel paths = No of brushes= ACoil Span = No: of slots per polesCoil sides per slot = Z

SCoil sides per pole = Z

PBack pitch = YbFront pitch = YfWinding pitch = YCommutator pitch = YcYc , Yb and Yf will be always an odd integerY is always an even integerProgressive Winding + sign , Retrogressive Winding - sign





DESIGN OF WINDING

Bottom coil side of current coil = Top coil side of current coil +Back Pitch (Both Lap & Wave)Top coil side of next coil = Bottom coil side of current coil - FrontPitch (Lap)Top coil side of next coil = Bottom coil side of current coil + FrontPitch (Wave)• Winding Calculations• Back Connections• Front Connections• Winding Table

Ring Diagram





Example 1Design and draw the developed winding diagram for a 4 pole, 8slots, double layer simplex lap winding for a DC generator. Show theconnections to equalizer rings.P = 4 , S = 8C = 8Coil sides per slot = 2Z = 16Coil sides per pole = Z

P = 164 = 4

Yb = 2CP ±K = 2∗8

4 ±K = 5(Progressive) or 3(Retrogressive)Yc = ±1(Simplex) ; Y = ±2 (Yc = Y/2)Yf = Yb - Y = 5 - 2 = 3No of equalizer rings, m = Z

2P or CP = 8

4 = 2No of tappings to one equalizer rings =P

2 = 42 = 2

Distance between adjacent tappings = 2CmP = 2∗8

2∗4 = 2Akhil A. Balakrishnan (JECC) Lecture Notes As on January 12, 2014 24 / 44




Winding Calculations1+5=6 6-3=33+5=8 8-3=5

5+5=10 10-3=77+5=12 12-3=99+5=14 14-3=11

11+5=16 16-3=1313+5=18(2) 18-3=1515+5=20(4) 4-3=1

Back Connections1←63←8

5←107←129←14

11←1613←18(2)15←20(4)

Front Connections6→38→5

10→712→9

14→1116→1318→15

4→1Winding Table

1←6→3←8→5←10→7←12→9←1414→11←16→13←18(2)→15←20(4)→1

Ring Diagram





Lap Winding





Example 2

Design and draw the developed winding diagram for a 4 pole, 13slots, double layer simplex wave winding with 13 commutatorsegments.P = 4 , S = 13C = 13Coil sides per slot = 2Z = 26Coil sides per pole = Z

P = 264 = 6.5

Coil sides per pole should be an integer, Coils sides per pole = 6Yb = 2C

P ±K = 2∗134 ±K = 7(Progressive) or 5(Retrogressive)

Y = 2C±2P/2 = 2∗13±2

4/2 = 14 , Yc should be always an odd integerYf = Y - Yb = 14 - 7 = 7





Winding Calculations1+7=8 8+7=15

15+7=22 22+7=29(3)3+7=10 10+7=17

17+7=24 24+7=31(5)5+7=12 12+7=19

19+7=26 26+7=33(7)7+7=14 14+7=21

21+7=28(2) 2+7=99+7=16 16+7=23

23+7=30(4) 4+7=1111+7=18 18+7=25

25+7=32(6) 6+7=1313+7=20 20+7=27(1)

Back Connections1←8

15←223←10

17←245←12

19←267←14

21←28(2)9←16

23←30(4)11←18

25←32(6)13←20

Front Connections8→15

22→29(3)10→17

24→31(5)12→19

26→33(7)14→21

2→916→234→11

18→256→13

20→27(1)Winding Table Ring Diagram1←8→15←22→29(3)←10→17←24→31(5)←12→19←26→33(7)←14

14→21←28(2)→9←16→23←30(4)→11←18→25←32(6)→13←20→27(1)Akhil A. Balakrishnan (JECC) Lecture Notes As on January 12, 2014 28 / 44




Wave Winding





Exercises

1 Design and draw the developed winding diagram for a 4 pole, 12slots, double layer simplex lap winding for a DC generator with 12commutator segments.

2 Design and draw the developed winding diagram for a 4 pole simplexwave winding having 25 slots, 25 coils and 25 commutator segments.

3 Design and draw the developed winding diagram for a 4 pole, 24slots, double layer simplex lap winding for a DC generator with 24commutator segments.





AC MACHINE WINDING

Identical to DC machine windingIn an AC winding, the commutator & its connection are notrequired.AC machine winding may be open, in the case of star windings andclosed in the case of delta windings





CLASSIFICATION





IMPORTANT TERMS USED IN WINDING

Slots per pole per phase(spp): To divide the slots into differentphase-groups.• spp is an integer : Integral Slot winding .• spp is a fraction : Fractional Slot winding .

Coil Pitch or coil span: Distance between two active coil sides of acoil in terms of slots.• coil pitch = pole pitch → Full pitched winding .• coil span < pole pitch → Short pitched winding .





SINGLE LAYER WINDING

Three phase windings are of two types:• Single Layer winding → Rarely Used• Double Layer winding .

Disadvantages of single layer windings are:• Inconvenience in arrangement of the overhang.• High cost in production.• Chording & use of fractional spp is not possible.

Single layer windings have one coil side per slot→ A coil completely occupies 2 slotsClassified into:• Mush Type.• Concentric Type.





MUSH WINDING

All coils have same spanOne coil side is longer than the otherLong and short coil side occupy alternate slotsCoil span should be odd





Example 3Draw a mush winding diagram for a 4 pole, 36 slots,three phasearmature.P = 4 , S = 36Slots per pole per phase(spp) = 36

4∗3 = 3One pole phase group consists of 3 slotsCoil sides are arranged as alternate long and short coil sides.Coil span = pole pitch = 36

4 = 9 slotsAngle between two consecutive slots = 180◦

9 = 20◦ electricalStart of phase R is assumed to be in slot no: 1Start of Y phase lies 120◦ electrical apart from Phase RStart of B phase lies again 120◦ electrical apart from Phase Y.No: of coils corresponding to 120◦ electrical= 120

20 = 6 slotsStart of coil side of phase Y lies in slot no: 7 andStart of coil side of phase B lies in slot no: 13





Mush Winding





CONCENTRIC WINDING

Made up of concentric coils of different pitches, for each pair ofpolesDivided into two main groups:• Unbifurcated winding.→ A pair of adjacent pole phase groups form a concentric coil.

• Bifurcated winding.→ Each pole phase groups is split into two sets of concentric coil,sharing its return coil sides with another such group.

Overhang should be accommodated in separate planesPole pairs is even → Can be accommodated in 2 planes.Pole pairs is a multiple of 3 → Can be accommodated in 3 planes.→ If overhang has to be accommodated in 2 planes, a cranked coilgroup results.





Example 4

Draw a single layer concentric unbifurcated winding diagram withtwo plane overhang, for a three-phase, 48 slots, 8 pole, AC armature.P = 8 , S = 48Slots per pole per phase(spp) = 48

8∗3 = 2One pole phase group consists of 2 slotsCoil span = pole pitch = 48


6 = 30◦ electricalNo: of coils corresponding to 120◦ electrical= 120

30 = 4 slotsOne coil group is placed in four slots, one pole pitch apart.No: of coil groups = 48

4 = 12No: of pole pairs is even, hence overhang is arranged in two planes





Unbifurcated Concentric Winding





Example 5Develop a single layer winding concentric unbifurcated type windingdiagram with two plane overhang for a three phase, 36 slots, 6 polearmature.P = 6 , S = 36Slots per pole per phase(spp) = 36

6∗3 = 2One pole phase group consists of 2 slotsTwo coil sides are split into 2 sets of concentric coils sharing itsreturn coil side with another group.Coil span = pole pitch = 36



30 = 4 slotsNo: of coil groups = 36

4 = 9 , No: of pole pairs = 3Overhang can be accommodated in 3 planesIf the overhang is to be accommodated in 2 planes, we get crankedcoil groups.





Unbifurcated Concentric Winding with Cranked Coil Group





Example 6For a three phase AC machine, the armature is having 24 slots. Asingle layer concentric bifurcated winding for four poles is to bemade. Draw the developed winding diagram with the overhang inthree planes.P = 4 , S = 24Slots per pole per phase(spp) = 24

4∗3 = 2One pole phase group consists of 2 slotsTwo coil sides are split into 2 sets of concentric coils sharing itsreturn coil side with another group.Coil span = pole pitch = 24



30 = 4 slotsOne coil group is placed in two slots.No: of coil groups = 24

2 = 12.Overhang is accommodated in 3 planes.





Bifurcated Concentric Winding




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