- Lap Winding Definition: A lap winding is defined as a winding where successive coils overlap and connect to the same commutator segment under the same magnetic pole.
- Simplex Lap Winding: In Simplex Lap Winding, the number of parallel paths between the brushes equals the number of poles.
- Duplex Lap Winding: In Duplex Lap Winding, the number of parallel paths between the brushes is twice the number of poles.
- Lap Winding Formula: Important formulae include Back pitch (YB), Front pitch (YF), Resultant pitch (YR), and Commutator pitch (YC).
- Lap Winding Diagrams: Diagrams illustrate the coil connections in both Simplex and Duplex Lap Windings.
Armature windings can be classified into two types – lap windings and wave windings. Here we are going to discuss lap windings and the two main types of lap windings in DC machines.
These are known as Simplex Lap Windings and Duplex Lap Windings.
What is a Lap Winding?
A lap winding is a winding in which successive coils overlap each other. It is named a “Lap” winding because it doubles or laps back with its succeeding coils. A diagram of a lap winding configuration is shown below.
In lap winding, the finishing end of one coil is connected to one commutator segment, and the starting end of the next coil under the same pole is connected to the same commutator segment.
Here we can see in the picture, the finishing end of coil – 1 and the starting end of coil – 2 are both connected to the commutator segment – 2 and both coils are under the same magnetic pole that is the N pole here.
There are two different types of Lap Windings:
- Simplex Lap Winding
- Duplex Lap Winding
Simplex Lap Winding
A winding where the number of parallel paths between the brushes equals the number of poles is called Simplex Lap Winding.
Duplex Lap Winding
A winding where the number of parallel paths between the brushes is twice the number of poles is called Duplex Lap Winding.
Some important points to remember while designing the Lap winding:
If,
- Z = the number of conductors
- P = number of poles
- YB = Back pitch
- YF = Front pitch
- YC = Commutator pitch
- YA = Average pole pitch
- YP = Pole pitch
- YR = Resultant pitch
Then, the back and front pitches are of opposite sign and they cannot be equal.
YB = YF ± 2m
- m = multiplicity of the winding.
- m = 1 for Simplex Lap winding
- m = 2 for Duplex Lap winding
When,
YB > YF, it is called progressive winding.
YB < YF, it is called retrogressive winding.
The back pitch and front pitch must be odd.
Resultant pitch (YR) = YB – YF = 2m
YR is even because it is the difference between two odd numbers.
Commutator pitch (YC) = ±m
Number of parallel path in the Lap winding = mP
Let us start from 1st conductor,
| Back connections | Front connections |
| 1 to (1+YB) = (1+5) = 6 | 6 to (6-YF) = (6 – 3) = 3 |
| 3 to (3+5) = 8 | 8 to (8-3) = 5 |
| 5 to (5+5) = 10 | 10 to (10-3) = 7 |
| 7 to (7+5) = 12 | 12 to (12-3) = 9 |
| 9 to (9+5) = 14 | 14 to (14-3) = 11 |
| 11 to (11+5) = 16 | 16 to (16-3) =13 |
| 13 to (13+5) = 18 = (18-16) = 2 | 2 to (18-3) = 15 |
| 15 to (15+5) = 20 = (20-16) = 4 | 4 to (20-3) = 17 = (17-16) = 1 |
Advantages of Lap Winding
The advantages of lap windings include:
- This winding is necessarily required for large current applications because it has more parallel paths.
- It is suitable for low voltage and high current generators.
Disadvantages of Lap Winding
The disadvantages of lap windings include:
- It produces less emf compared to wave winding. This winding needs more conductors to produce the same emf, leading to higher winding costs.
- It has less efficient utilization of space in the armature slots.
thank you sir ….easy to understand
No problem at all Hamza – happy to hear it helped!