Research On3kV Less-resin VPI Insulation Structure

As the progress of new material and new technology of the large-and-middle-sized high-voltage electrical insulation structure, the insulation thickness has been thinning constantly. Reducing the center height of motor core can reduce both the material and cost. Although we has used3KV6895moderate-resin insulation structure for several decades, which is reliable, the structure is too thick. It can’t keep up with the demand of market when thinned less-resin insulation structure has been used by more and more manufactories. The research of3KV less-resin VPI insulation structure will be extremely urgent as the result of progress and maturation of less-resin insulation technology.In this paper, the thickness and the material of stator inter-turn and main insulation are determined, and the insulation structure of stator is designed. Whether the insulation structure is reliable is determined by testing the dielectric loss, dielectric strength, electrical aging and thermo stability of test bars. Finally we use a new insulation structure evaluation method of the isothermal relaxation current to research.Study has shown that the inter-turn thickness of3KV less-resin insulation structure can be reduced from0.40mm to0.30mm, and thickness of main insulation from1.1mm to0.78mm. Compared to moderate-resin insulation system, advanced less-resin insulation system contains more mica and has higher level field intensity and heat resistance. Instantaneous breakdown strength of insulation is7times greater than UN. The insulation structure has passed4UN+5KV lighting impulse voltage and0.65(4UN+5KV) inter-turn insulation impulse voltage. Voltage endurance test lasted longer than1200hours that is standard high-class grade. Decline rate of thermo stability test voltage is less than30%. These test proved that the insulation structure is stable and reliable.