The armature winding is a critical component of rotating machines, as it is responsible for the energy conversion process. This process involves the conversion of mechanical energy into electrical energy, and vice versa. Armature windings come in two main types: lap winding and wave winding. Lap winding involves passing the wire around a central core multiple times before connecting it, while wave winding involves passing the wire around the core once, then connecting it before passing it around again. Both of these winding types are important for the efficient functioning of a rotating machine.
Lap Winding
In lap winding, the armature coils are arranged in such a way that the parallel paths and poles are equal in number. Each end of an armature coil is connected to the adjacent segment on the commutator. To facilitate current flow, the same number of brushes are used as the number of parallel paths, and these brushes are divided into two groups of positive and negative polarity. This type of winding is mainly used in electrical motors that require low voltage and high current.
Type of lap winding
Simplex Lap Winding
Simplex lap winding is a winding technique in which the terminating end of one coil is joined to the commutator segment and the starting end of the next coil is placed under the same pole. This winding technique is used for applications requiring a similar number of parallel paths as the number of poles of the windings.
Duplex Winding
Duplex winding is a winding technique used in applications requiring heavy current. In this winding technique, the number of parallel paths between the pole is twice the number of poles. This is achieved by placing two similar windings on the same armature and connecting the even number commutator bars to one winding and the odd number to the second winding.
Triplex Lap Winding
Triplex lap winding is a winding technique in which the windings are connected to one-third of the commutator bars. This winding technique is used for applications requiring a large number of paths, although it requires many conductors which increases the overall cost of the winding.
Wave Winding
In wave winding, two parallel paths are provided between the positive and negative brushes. The parallel paths are connected through the armature coils by connecting the finishing end of one armature coil to the starting end of the other armature coil commutator segment at some distance apart. This winding style is mainly used in machines that require a high voltage but low current, and the number of brushes is equal to the number of parallel paths.
The armature winding of an electrical motor is said to be retrogressive if, after passing through one electrical cycle, the winding is found to have been displaced to a slot to the left of its initial starting point. This displacement of the winding is a consequence of the rotating magnetic field produced by the stator and is a unique characteristic of the motor’s design.
A progressive winding occurs when the armature windings are displaced one slot to the right. This type of winding allows for a smoother transition between the poles of the motor and can reduce the noise caused by the motor running.
The two layers of winding must be assumed, with conductor AB located at the upper layer half of the slot on either the left or right side. The YB is the back pitch, while YF is the front pitch. These two pitches together are nearly equal to the pole pitch of the winding.
The equation gives the average pitch of the winding.
The average pitch can be calculated by dividing the total number of conductors or coils (ZA) by the number of sides.
Z = PYA ± 2, is always an even integer.
“P” is number of poles
And “p” is always even