A Thermal Model of an Electric Rolling-Mill Machine

This paper presents a thermal model of the armature winding, which incorporates the thermal characteristics of three main armature components in the transient processes—namely, a winding, its insulation, and an armature core. The transfer factors of the insulation gap are experimentally determined. This enables us to sufficiently accurately describe the change of the insulation overtemperature in the early stage of the transient process. The graphs of permissible overload time of a rolling-mill motor depending on the overload ratio are obtained. Recommendations are made on a load of a rolling-mill motor. They are represented as a graph that takes into account the heating inhomogeneity of different surface areas of the armature-winding section in the transient processes.