Measurement of Insulation Resistance and Absorption Ratio of Winding: measure the insulation resistance and absorption ratio (polarization index) of the high-voltage winding (three-phase short-circuiting) to the low-voltage winding (three-phase short-circuiting and grounding of low-voltage winding) and measure the insulation resistance and absorption ratio (polarization index) of the low-voltage winding (three-phase short-circuiting) to the high-voltage winding (three-phase short-circuiting and grounding of high-voltage winding) and measure the insulation resistance of the core to the ground. And note down the testing results and the environmental temperature