Diagnostics and protection of the winding insulation of asynchronous motors operating in aggressive environments

Asynchronous motors work under drastic dusty conditions at industrial enterprises. As a consequence dust and moisture work into the winding. The location where the winding gets out of the groove is subject to dynamic forces, it resulting in microcracks. As a result, conducting bridges are formed on the frontal end of the winding. The amount of current flowing through the dust layer depends on the material and its thickness. Studies of this issue have not been conducted in modern literature. The task of timely detection and diagnosis of the natural aging of insulation, its becoming dusty and wet is relevant. As a result of physical pheno-mena simulation the relationship curves of the surface resistance dependence on different materials and thicknesses of the dust layers have been obtained. An expression that makes it possible to define the current flowing through the layer of dust has been derived. The effect of moisture on the insulation resistance and the dust material has been defined. The corresponding curves have been obtained. The change in rate of surface conductance that makes it possible to diagnose the covering of the insulation surface with non-conductive dust has been defined. Based on the analysis and experimental modeling a method of timely detection of the winding becoming dusty and moist has been developed. This method is implemented in a device consisting of a low voltage source, an insulation resistance measuring unit, a surface state sensor, a signalling and switching unit, a microprocessor unit and a power supply unit