What is the function of the bands when they are distributed along the axial length of armature?

The bands distributed along the axial length of an armature in electrical machines (such as generators and motors) have the primary function of securing the armature windings in place against centrifugal forces. When an electrical machine operates, the armature rotates at high speeds, and the windings experience significant centrifugal forces that can cause them to move or even come loose. If the windings were to move, it could lead to electrical short circuits, reduced efficiency, or even catastrophic failure of the machine. The bands, which are typically made of non-magnetic materials like steel or sometimes high-strength composites, are tightly fitted around the armature windings.

These bands must be properly sized and tensioned to ensure they can effectively counteract the forces acting on the windings throughout the operating range of the machine. They also help to maintain the structural integrity of the armature and improve the overall reliability and lifespan of the device. In addition to mechanical securement, these bands can also aid in heat dissipation by providing additional surface area for heat transfer to the surrounding environment, although this is a secondary function compared to their primary role of mechanical reinforcement.