Armature wire is a type of stranded, annealed copper wire with a soft cotton braid used primarily in rotor windings for low-voltage, high-current motors and generators.
Designed to carry significant current at low voltages, armature wire is typically made from soft-drawn, annealed copper to provide maximum conductivity and flexibility. Its stranded construction, paired with a straight lay configuration, allows for optimal formability within armature slots of rotating machinery. The soft white cotton braid serves as a non-conductive insulating layer, protecting the conductor while offering compressibility for tight motor windings.
In commercial and industrial environments, armature wire plays a critical role in the performance and longevity of motors and generators by ensuring efficient current transfer to the rotor. Its ability to flex and conform without breaking makes it ideal for repeated cycles and mechanical stress within motor windings.
Also referred to as rotor winding wire in some industrial contexts.
Often recognized under guidelines issued by the Institute of Electrical and Electronics Engineers (IEEE) and UL (Underwriters Laboratories) for its role in electrical rotating machinery.
The use of cotton-braided copper wire for armatures dates back to early electrical engineering practices in the late 19th and early 20th centuries, when natural fiber insulation was standard. While modern insulation materials are widely used today, cotton-braided versions remain relevant in specialized equipment where compressibility, temperature tolerance, or historical consistency is required.