10/29/2010 11:32 AM EMD M.V.Ramana Rao • Armature winding of a machine is defined as an arrangement of conductors designed to produce emfs by relative motion in a heteropolar magnetic field. • The action of rotating electromagnetic machines is dependent upon the conversion of power that takes place through the medium of magnetic field an emf being induced in the winding that experiences a change of flux linkages. Electric Circuit Electric Circuit Armature Windings Armature Windings • Electrical machines employ groups of conductors distributed in slots over the periphery of the armature. The groups of conductors are connected in various types of series—parallel combinations to form armature winding. • The conductors are connected in series so as to increase the voltage rating while they are connected in parallel to increase the current rating.
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10/29/2010 11:32 AM EMD M.V.Ramana Rao
• Armature winding of a machine is defined as an arrangement ofconductors designed to produce emfs by relative motion in aheteropolar magnetic field.• The action of rotating electromagnetic machines is dependentupon the conversion of power that takes place through the medium ofmagnetic field an emf being induced in the winding that experiencesa change of flux linkages.
Electric CircuitElectric CircuitArmature WindingsArmature Windings
• Electrical machines employ groups of conductors distributed inslots over the periphery of the armature. The groups of conductorsare connected in various types of series—parallel combinations toform armature winding.• The conductors are connected in series so as to increase the voltage rating whilethey are connected in parallel to increase the current rating.
Single Layer And Two Layer WindingsSingle Layer And Two Layer Windings
(1)(1) Single layer winding.Single layer winding. Fig. (a) shows an arrangement for a single Fig. (a) shows an arrangement for a single layer winding. layer winding. In this type of winding arrangement, the whole of the slot is In this type of winding arrangement, the whole of the slot is occupied by one coil side of a coil. Single layer windings are not occupied by one coil side of a coil. Single layer windings are not used for machines having commutators. used for machines having commutators. However, some advantages of these windings areHowever, some advantages of these windings are
Armature windings are classified into two categoriesArmature windings are classified into two categories(i) Closed type and (ii) Open type.(i) Closed type and (ii) Open type.
•• TheThe currentcurrent flowingflowing intointo aa closedclosed windingwinding isis throughthrough brushesbrushesplacedplaced onon aa commutatorcommutator whosewhose segmentssegments areare connectedconnected toto differentdifferentarmaturearmature coilscoils..
•• The closed windings are used in dc, and ac. commutator machines The closed windings are used in dc, and ac. commutator machines Closed windings are always double layer type.Closed windings are always double layer type.
WithWith averageaverage ororeffectiveeffective coilcoil spanspanbeingbeing 66 slotsslots (equal(equal totoslotsslots perper pole)pole) andandthereforetherefore thethe windingwindingbehavesbehaves asas aa fullfull pitchpitchwindingwinding..Hemitropic winding having 3 slots per poleHemitropic winding having 3 slots per pole
per phase with a 2 plane overhang. per phase with a 2 plane overhang.
2 2 -- plane overhang.plane overhang.
10/29/2010 11:32 AM EMD M.V.Ramana Rao
Winding shown in Fig. the 3 coils in a coil group have an average Winding shown in Fig. the 3 coils in a coil group have an average (effective) coil span of 9 slots (which is equal to slots per pole).(effective) coil span of 9 slots (which is equal to slots per pole).
The same winding may have a 3 plane overhang as shown in The same winding may have a 3 plane overhang as shown in Fig. above Fig. above
3 plane overhang3 plane overhang
10/29/2010 11:32 AM EMD M.V.Ramana Rao
Whole Coil WindingsWhole Coil Windings•• These are also known as These are also known as bifurcatedbifurcated windings.windings.
Draw the winding diagrams of a following 3-phase, 36slots, 6 pole, a.c. armature for Following single layerconcentric types of windings :(i) Hemitropic-2 plane overhang (ii) Hemitropic-3 plane
overhang. (iii) Whole coil-3 plane overhang.
Solution
Slots per pole per phase = 36/3*6 = 2
Slots per pole = 36/6 = 6
\ Angle between consective slots α s = 180/6 = 30 0
AssignmentAssignment1. Draw the winding diagrams of a following 3-phase, 36slots, 6
pole, a.c. armature for Following single layer concentric types of windings (i) Hemitropic-2 plane overhang (ii) Whole coil-3 plane overhang.
2. Draw the winding diagrams for a 4 pole, 36 slots, 3-phase, MUSH connected armature.
Instructions :Instructions :1.1. All assignment hat to send through eAll assignment hat to send through e--mail only as the attachment.mail only as the attachment.2.2. Assignment should be sent the following eAssignment should be sent the following e--mailmail
3. Assignment should be in the creative nature. 3. Assignment should be in the creative nature. 4. Assignment must be sent on or before 154. Assignment must be sent on or before 15thth August 2008 August 2008
10/29/2010 11:32 AM EMD M.V.Ramana Rao
Mush windingDraw the winding diagrams for a 4 pole, 24 slots, 3-phase,MUSH connected armature.Solution :-
Slots per pole per phase = 24
3*4= 2
Coil span = 24/4 = 6 slotsThis is an even numberand hence winding is notPossible with coil spanof 6 slots
• Double layer windings are universally used for armatures ofsynchronous generators and motors and most induction motors oflarge and medium sizes.
• Double layer windings may be classified into two categoriesdepending upon the method used to bring about the transition fromthe top layer to bottom layer.These are(i) lap type, and (ii) wave type.
• Lap windings have their widest field of application in the stators of high speed machines.
• Wave windings are used for wound rotors of medium and large size induction motors.
10/29/2010 11:32 AM EMD M.V.Ramana Rao
• These windings are the same as used in d.c. machines and givetwo different shapes to the end connections. The coils used indouble layer windings are diamond shaped as in dc machines
Example : Example : Give the layout of a lap winding for the stator of a 3 phase ac having Give the layout of a lap winding for the stator of a 3 phase ac having 4 poles and 24 slots. There are 2 coil sides per slot.4 poles and 24 slots. There are 2 coil sides per slot.
Thus there are 3 phase groups per pole each comprising of Thus there are 3 phase groups per pole each comprising of qq = 2 = 2 slots. The distribution of slots, of phase sequence RYB, isslots. The distribution of slots, of phase sequence RYB, is
Example : Example : Give the layout of a wave winding for the rotor of a 3 phase, 4 pole Give the layout of a wave winding for the rotor of a 3 phase, 4 pole induction motor having 24 slots. Each slot contains 2 coil sides.induction motor having 24 slots. Each slot contains 2 coil sides.
Give the layout of a double layer lap type winding for a 3 Give the layout of a double layer lap type winding for a 3 phase, 8 pole. 54 slot armature. phase, 8 pole. 54 slot armature.
••These slots, when arranged according to their position in These slots, when arranged according to their position in the machine arethe machine are1,2,3 1,2,3 8,98,9 15,16 15,16 22,2322,23
These slots, when arranged according to their position in These slots, when arranged according to their position in the machine arethe machine are4, 5 10, 11, 12 17, 184, 5 10, 11, 12 17, 18 24, 2524, 25
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The remaining 9 slots out of total of 27 in a unit, belong to phase Y. These, when arranged according to their sequence in the machine, are
Give the winding layout of a 30 slot, 4 pole 3Give the winding layout of a 30 slot, 4 pole 3--phase wave wound phase wave wound rotor of an induction motor.rotor of an induction motor.
Each unit covers 2 poles and there are two such units. Each unit Each unit covers 2 poles and there are two such units. Each unit contains 5 slots of each phase. Each phase in a unit hascontains 5 slots of each phase. Each phase in a unit has