Insulation defect detection of high voltage generator stator core
First Claim
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1. A method for detecting an insulation defect in a generator core, comprising:
- flowing an alternating excitation current at a first excitation frequency through an excitation winding adjacent the generator core to induce first eddy currents between laminations at the defect;
measuring a first potentiometer voltage indicating magnetic flux caused by the first eddy currents induced at the first excitation frequency;
flowing an alternating excitation current at a second excitation frequency through the excitation winding adjacent the generator core to induce second eddy currents between the laminations at the defect;
measuring a second potentiometer voltage indicating magnetic flux caused by the second eddy currents induced at the second excitation frequency; and
determining a severity of the defect and a depth of the defect using a response voltage relationship among the potentiometer voltages, the excitation frequencies, the severity of the defect, and the depth of the defect,wherein the response voltage relationship comprises fitting parameters and a term wherein the excitation frequency is raised to a function of a fitting parameter.
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Abstract
In a general methodology for insulation defect identification in a generator core, a Chattock coil is used to measure magnetic potential difference between teeth. Physical knowledge and empirical knowledge is combined in a model to predict insulation damage location and severity. Measurements are taken at multiple excitation frequencies to solve for multiple characteristics of the defect.
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Citations
19 Claims
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1. A method for detecting an insulation defect in a generator core, comprising:
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flowing an alternating excitation current at a first excitation frequency through an excitation winding adjacent the generator core to induce first eddy currents between laminations at the defect; measuring a first potentiometer voltage indicating magnetic flux caused by the first eddy currents induced at the first excitation frequency; flowing an alternating excitation current at a second excitation frequency through the excitation winding adjacent the generator core to induce second eddy currents between the laminations at the defect; measuring a second potentiometer voltage indicating magnetic flux caused by the second eddy currents induced at the second excitation frequency; and determining a severity of the defect and a depth of the defect using a response voltage relationship among the potentiometer voltages, the excitation frequencies, the severity of the defect, and the depth of the defect, wherein the response voltage relationship comprises fitting parameters and a term wherein the excitation frequency is raised to a function of a fitting parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A non-transitory computer-readable medium having stored thereon computer readable instructions for detecting an insulation defect in a generator core, wherein execution of the computer readable instructions by a processor causes the processor to perform operations comprising:
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receiving a measurement of a first potentiometer voltage indicating magnetic flux caused by first eddy currents induced between laminations at the defect by flowing an alternating excitation current at a first excitation frequency through an excitation winding adjacent the generator core; receiving a measurement of a second potentiometer voltage indicating magnetic flux caused by second eddy currents induced between laminations at the defect by flowing an alternating excitation current at a second excitation frequency through the excitation winding adjacent the generator core; and determining a severity of the defect and a depth of the defect using a response voltage relationship among the potentiometer voltages, the excitation frequencies, the severity of the defect, and the depth of the defect, wherein the response voltage relationship comprises fitting parameters and a term wherein the excitation frequency is raised to a function of a fitting parameter. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for detecting an insulation defect in a generator core, comprising:
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flowing an alternating excitation current at a first excitation frequency through an excitation winding adjacent the generator core to induce first eddy currents between laminations at the defect; measuring a first potentiometer voltage indicating magnetic flux caused by the first eddy currents induced at the first excitation frequency; flowing an alternating excitation current at a second excitation frequency through the excitation winding adjacent the generator core to induce second eddy currents between the laminations at the defect; measuring a second potentiometer voltage indicating magnetic flux caused by the second eddy currents induced at the second excitation frequency; and determining a severity of the defect and a depth of the defect using a response voltage relationship among the potentiometer voltages, the excitation frequencies, the severity of the defect, and the depth of the defect, wherein the response voltage relationship comprises fitting parameters and an exponential function of the depth of the defect, wherein an operand of the exponential function is a logarithmic function of the excitation frequency.
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Specification