Specifications

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5. DEVELOPMENT OF WINDING - DC MACHINE
5.1 GENERAL PROCEDURE FOR DEVELOPMENT OF WINDING DIAGRAM
1. Calculate the number of coil sides for the main winding diagram.
2. Calculate the back pitch, Y
b
, the winding pitch, Y, and the front pitch, Y
f
, using equations
3.17, 3.18, and 3.20 respectively.
3. Form a winding table using the back pitch, Y
b
, and the front pitch, Y
f
.
4. For drawing the main winding diagram, draw solid vertical lines of equal length at equal
distance equal to number of coils. These solid lines indicate the top layer coil sides.
5. Draw dotted vertical lines of same length and distance close to the solid vertical lines
(equal to number of coils). These dotted lines indicate bottom layer coil sides.
6. Assign odd numbers to the top left side of the solid lines and even number to the
bottom right side of the dotted lines.
7. Complete the connection to the coil sides using the winding table, with solid lines for
top layer coil sides and dotted lines for bottom layer coil sides.
8. Using the main winding diagram, draw solid vertical lines (equal to number of coils)
from the top mid-point of each front end connections.
9. Represent commutator segments (equal to no. of coils) by rectangular boxes below
the front end connections.
10. Divide the coils by the number of poles. This gives the allocation of coil sides to pole
regions.
11. Find the current direction by applying Fleming’s right hand rule, when the mode of
operation is a generator and Fleming’s left hand rule, when the mode of operation is a
motor. Or the current direction to all coil sides can be arbitrarily assumed. Mark
downward current direction for the coil sides under the north pole regions and upward
current direction under south pole regions.
12. To fix the brush arm positions and to find the number of parallel paths offered by the
armature winding, draw the commutator ring diagram or equivalent end ring diagram.
13. To draw the commutator ring diagram or equivalent end ring diagram, draw vertical
solid lines equal to number of coil sides and join them with reference to winding table.
14. Also mark the current direction through the coil sides with reference to main winding
diagram.
5.2 DOUBLE LAYER SIMPLEX LAP WINDING DIAGRAM
Draw the winding diagram for a 2 pole, 6 slot simplex lap connected dc machine with
commutator having 6 segments. Indicate the position of brushes.
Solution : Slots per pole = = = 3; Number of coils, C=number of commutator segments=6
Number of coil sides = 2C = 12 ; Therefore, coil sides per slot = = 2
From equation 3.2, the back pitch, (odd integer)
s
p
6
2
2 C
P
12
2
Y
b
= + K = + K = 6 + 1 = 7
12
6