Assessment of factors influencing electroosmotic drying of moistened insulation in locomotive traction electric motors

Objective: to assess the factors influencing the electroosmotic drying rate of moistened insulation of windings in a traction DC motor. Methods: experimental study with processing of results using mathematical statistics methods. Results: two series of experiments on electroosmotic drying of moistened insulation in a traction DC motor were carried out at different applied voltages and C-filter capacitances. A sample comprising 60 insulation resistance measurements of the TEM main poles, 30 per series, was obtained. Regression analysis was performed, yielding coefficients of determination of 0.996 with respect to voltage and 0.804 with respect to C-filter capacitance. The consistency of the experimental data was confirmed by the Wilcoxon test. A two-factor analysis of variance for related samples was also carried out. The applied voltage and the C-filter capacitance each exerted a significant effect on the electroosmotic drying rate. The individual-difference and the sample-difference factors were determined as insignificant. Increasing the electroosmotic drying voltage from 500 to 2500 V have produced a quadratic rise in the insulation resistance of the main poles amounting to 210%, whereas lowering the ripple coefficient from 0.2 to 0.04 yielded a 45% reduction in insulation resistance. Practical significance: the data obtained can be employed to develop an electroosmotic drying technology for TEM in depot service during subzero temperatures periods.