Government Engineering College, Valsad Subject :- Elements Of Electrical Design

Submitted to :- J.B.patel Sir Group : - 11 SR NO. ENROLL NO. NAME 1 130190109017 JIVANI DHRUPAL 2 130190109018 JOSHI GOPAL 3 130190109015 THAKOR JIGAR 4 130190109024 MALAVIYA CHARVIN Submitted to :- J.B.patel Sir

Concentric winding

Introduction : Three-phase concentric winding consists of coil groups laid in the slots so that all the coils of each group are concentric. That is, the coil with the smallest slot pitch is surrounding by the coil with the next larger slot pitch and so on to make up a coil group. Each coil consists of several turns and the cross-over from one coil to the next is indicated by a short slanted line (jumper).

Types of AC armature winding ; Concentrated armature winding; Single layer winding Double layer winding Concentric winding Mush winding Lap winding Wave winding Hemitro-pic Whole coil winding Integral slot Fraction-al slot Integral slot Fraction-al slot

Concentrated armature winding ; Concentrated winding is employed where number of slots on the armature is equal to number of poles in the machine. This armature winding of alternator gives maximum output voltage but not exactly sinusoidal. Here, number poles = number of slots = number of coil sides , which is shown in below fig. Here, one coil side is inside one slot under one pole and other coil side inside other slot under next pole.

Construction of concentrated winding ; In order to construct the diagram for a winding, the following data must be known: S - The number of slots in the stator P – The number of poles m – The number of phases YS – The pitch of the winding a – The number of parallel circuits in the windings

The pitch of the winding is determined by the formula The pitch is the distance between two sides of a coil expressed as the difference between the numbers of the slots in which the sides lie. Another important value of the winding of ac machines is the number of slot per phase per pole denoted by the letter q. It can be determined by the formula

Example#1: on concentric winding Given data S=24; p=4;m=3; a=1; type=Concentric Solution The number of coil groups, K The number of slots per pole per phase, q Coil pitch The shorter coil pitch = YS-1=6-1=5 i.e. there is two coil groups per phase i.e. there are two coils in a group Full-Pitch ( average pitch)

The larger coil pitch = YS+1=6+1=7 The electrical angle,  The angle between adjacent slots,  The distance between the beginning of each phase,  If the beginning of Phase A is slot 1, then the beginning of phase B is slot 1+=5 and the beginning of phase C is slot 1+2=1+8=9

PROCEDURE FOR CONSTRUCTING OF CONCENTRIC WINDINGS Data: S= 24, P = 4, a = 1, q = 2, K = 6

Coil Groups of Phase A The first and second slots will be occupied by left-hand sides of the first coil group of phase A. Leave four, or 2q slots free for other two phases occupy slots 7 & 8 with the right hand side of the first coil group. Next to it will lie a second coil group of the same size which occupies slots 9,10,15,16.

Coil Groups of Phase B In order to find, where the second phase (B) should begin, it is necessary to know the angle between slots in electrical degrees. =180.P = 180.4 = 7200 – Electrical degree The angle between adjacent slots,  The distance between phase beginnings will have

Coil Groups of Phase C

Current direction N 1-6 S 7-12 N 13-18 S 19-24

Phase A – Coil groups interconnection

Phase B – Coil groups interconnection

Phase C – Coil groups interconnection

Terminals

THANK YOU