| 摘要 |
FIELD: electricity.SUBSTANCE: invention is related to the field of electric engineering, and namely to non-destructive quality control procedures for electrical products, in particular, to impregnation of windings of electrical machines. According to the suggested method for determination of impregnation coefficient for electrical machine windings impregnated by cured polymer composition capacitance values Cand Cin regard to the ground are measured for each electrical machine winding in the batch before and upon impregnation by the polymer composition and drying. Then, upon impregnation and drying of windings temperature of each winding Tis measured and through the wire of each tested winding stabilised direct current Iis passed and its values is selected depending on section area S of the winding wire strand within the range of maximum current density permitted for the material of the winding wire from jup to jwithin the range of values jS ?I?jS. At that the above selected current Iis passed through the winding during a certain period of time tand voltage drop is measured at the winding Uat the moment of stabilised current delivery to it and voltage drop at the winding Uat the above period of time t. Upon the above operations according to measurement results the impregnation coefficient Kis determined for each tested winding in the near-body cavities and impregnation coefficient Kof turn-to-turn cavities in the windings as per the following formulas:(4),(5), whereis equivalent capacity of in-series capacitance of enamel and frame insulation of the winding; p is a number of slots in the magnet core to which the tested part of the winding is placed; Sis an area of the slot surface; ?=8.854187·10is the electrical constant; ?is dielectric capacitivity of enamel film at the winding wire; ?is dielectric capacitivity of frame insulation; dis thickness of enamel insulation of the wire; dis thickness of frame insulation at the wire; cis specific heat capacity of the dried impregnation composition;is a limit mass of dry impregnation composition which can be placed in turn-to-turn cavities of the winding at 100% of their filling; dis density of dried impregnation composition; Sis cross-sectional area of the slot; lis length of the winding turn; Kis the slot filling coefficient; ? is temperature coefficient of the winding wire resistance; B= C+ Cis equivalent heat capacity of enameland frame insulation C= C× P × d× L × p × c; cis specific heat capacity of enamel; Dis the diameter of enamelled wire of the winding; Dis the diameter of the winding wire strand; lis rated length of the wire in the tested winding part; ?is enamel density; cis specific heat capacity of the frame insulation; P is the slot perimeter; dis thickness of the frame insulation; L is the slot length; ?is density of the frame insulation;is the constant rate; cis specific heat capacity of the material used for the winding wire strand; ?is specific resistivity of the material used for the winding wire at 20°C.EFFECT: simplification of the method due to avoidance of measuring capacity in regard to the ground for one random winding and self-capacitance before impregnation, dipping of the above winding into impregnating liquid with the known dielectric capacitivity and measuring of this winding capacity in regard to the ground and self-capacitance again with the winding placed in the impregnating liquid as well as die to avoidance of double measurements of self-capacitance for each of the tested winding before and upon impregnation, improvement of accuracy because the value of impregnation coefficient does not depend on relative position of turns in the slot, as well as increase in information content of control because this method allows to determine distribution of the impregnation composition inside the winding and impregnation coefficients for near-body and turn-to-turn cavities of windings.1 tbl, 2 dwg |
