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Note for Computer Aided Engineering Drawing - CAED By Ayush Agrawal

  • Computer Aided Engineering Drawing - CAED
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COMPUTER AIDED ELECTRICAL DRAWING (CAED) 10EE65 Winding Diagrams: (i) DC Winding diagrams (ii) AC Winding Diagrams Terminologies used in winding diagrams: Conductor: An individual piece of wire placed in the slots in the machine in the magnetic field. Turn: Two conductors connected in series and separated from each other by a pole pitch so that the emf induced will be additive. Coil: When one or more turns are connected in series and placed in almost similar magnetic positions. Coils may be single turn or multi turn coils. Conductor Pole pitch N S N S N S Coil side (a) Single turn Coil (b) 3 – turn coil (c) Multi turn coil Fig. 1 Different types of winding coils representations Coil group: One or more coil single coils formed in a group forms the coil group. Winding: Number of coils arranged in coil group is said to be a winding. Pole Pitch: Distance between the poles in terms of slots is called pole pitch. 1

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Fig. 2 Single and Multi turn coils Full Pitch winding: If the coil pitch for a winding is equal to pole pitch the winding is called full pitch winding Fig . Chorded winding: When the pitch of the winding is less than the full pitch or pole pitch then the winding is called short pitch winding or chorded winding. Fig. 3 Full pitched and short pitched coils Single layer winding: Only one coil side placed in one slot. Double layer winding: Two coil sides are placed in a single slot. Single and double layer windings are shown in Fig 4 2

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Fig.4 Single and double layer windings 3

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Classification of windings: Closed type and open type winding Closed type windings: In this type of winding there is a closed path around the armature or stator. Starting from any point, the winding path can be followed through all the turns and starting point can be reached. Such windings are used in DC machines. Open windings: There is no closed path in the windings. Such windings are used in AC machines. Fig. 5 Photographs of the windings and coils DC Windings: Two types of windings (a) Lap winding (b) Wave winding These two types of windings differ in two ways (i) number of circuits between positive and negative brushes, (ii) the manner in which the coil ends are connected. However the coils of both lap and wave windings are identically formed. TYPES AND SHAPES OF WINDING WIRES: The winding wires used in electrical motors are classified as follows. 1) Round wires 2) Rectangular straps 3) Stranded wires 1. Round Wires: It has thin and thick conductors and are used in semi-closed slot type motors and mush winding rotors. It is wounded in reels and available in Kilograms. 2. Rectangular straps: It is used in open type slot motors. These conductors are available as long straps in meters. They are used in the following places. 1) Low voltage motor windings. 2) Used as conductor in high current motor. 3) Series field motor winding coils. Winding Pitches: Back Pitch: The distance between top and bottom coil sides of a coil measured around the back of the armature is called back pitch and is designated as yb. Back pitch is approximately equal to number of coil sides per layer. Generally back pitch is an odd integer. Front Pitch: The distance between two coil sides connected to the same commutator segment is called the front pitch and is designated as yf. Winding Pitch: The distance between the starts of two consecutive coils measured in terms of coil sides is called winding pitch and is designated as Y. Y = yb – yf for lap winding Y = yb + yf for wave winding 4

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