METHOD FOR DETERMINING CHANGES IN THE LEVELS OF DISTRIBUTED LEAKAGE CURRENTS THROUGH THE INSULATION OF THE WINDING OF AN ELECTRIC MACHINE Russian patent published in 2021 - IPC G01R31/34 G01R31/52 

FIELD: measuring technology.

SUBSTANCE: invention relates to control and measuring equipment and can be used to determine changes in the levels of distributed leakage currents through the insulation of the winding to the body of an electric machine. Essence: an alternating voltage source is connected to the windings of two phases connected in series, and a measuring circuit containing a series-connected potentiometer with a graduated field, a microammeter, a two-position switch is connected to the beginning of the winding of the third phase and the body of an electric machine. In this case, the measuring circuit with the introduced potentiometer is connected to the beginning of the third phase winding and the housing by means of one of the switch positions, the potentiometer is output by moving the motor. At the moment of the appearance of a current reading on the microammeter that is different from the zero value, the value of the division on the field of the potentiometer corresponding to this moment is recorded. The output the potentiometer is continued, the current values of the microammeter and the corresponding values of the divisions on the field of the potentiometer are registered until the current value is stabilized. The function of the dependence of the current of the microammeter on the values of the divisions of the field of the potentiometer is obtained. The numbers of the winding turns corresponding to the values of the field divisions of the potentiometer based on their direct proportional dependence are determined. The function of the derivative of the function of the dependence of the current of the microammeter on the numbers of the winding turns corresponding to the values of the registered divisions of the field of the potentiometer is obtained. According to local changes in the ordinate levels of these functions on the winding turns, a local change in the levels of distributed leakage currents through the winding insulation to the housing on the turns from the beginning of the winding is estimated. The measuring circuit with the introduced potentiometer is connected to the end of the winding of the third phase and the body of the electric machine by means of another switch position, similarly local changes in the levels of distributed leakage currents through the insulation of the winding to the body on the turns from the end of the winding are determined. Further monitoring of changes in the levels of distributed leakage currents through the insulation of the winding on the housing is carried out. The trends of deterioration of the insulation condition, identify new areas with local changes in these currents are assessed. Similarly, changes in the levels of distributed leakage currents through the insulation to the housing of other windings of an electric machine are determined.

EFFECT: ability to detect sections of defective insulation and judge the trend of changes in the state of insulation.

1 cl, 2 dwg