System to provide low cost excitation to stator winding to generate impedance spectrum for use in stator diagnostics

• US 6,035,265 A
• Filed: 08/17/1998
• Issued: 03/07/2000
• Est. Priority Date: 10/08/1997
• Status: Expired due to Term

• Current Assignee: Baldor Electric Company (ABB Limited)
• Original Assignee: Reliance Electric Industrial Company (ABB Limited)
• Inventors: Dister, Carl J., DelVecchio, Perry A., Rogovin, Daniel N.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): MILLER, CRAIG S
• Application Number:
  US09/135,208
• Time in Patent Office: 568 Days
• Field of Search: 324/545, 324/546, 324/772, 338/823, 340/648, 702/57-59, 702/60, 702/64, 702/65, 702/76, 702/77, 702/81, 702/84, 702/182-183, 702/189-191
• US Class Current: 702/183
• CPC Class Codes: G01R 31/343 in operation

Abstract

A test procedure detects the onset of stator winding damage, identifies the failure mechanism, determines the winding'"'"'s susceptibility to further damage, and predicts stator winding failure. This is accomplished by introducing a high frequency signal onto power lines which feed the stator and monitoring a change in the capacitance between the individual windings during introduction of the high frequency signal. In order to monitor the change in capacitance, a current sensor and voltage sensor are used to measure the current and voltage on the power lines during introduction of the high frequency signal. Changes in the capacitance between the individual stator windings are reflected as changes in the broadband impedance response of the stator windings which can be calculated by dividing the measured voltage by the measured current.

Claims

1. A system for predicting stator winding damage in a motor during operation, comprising:

a signal generator coupled to a power line providing power to the motor, the signal generator introducing a high frequency signal on the power line so as to probe stator windings of the motor at frequencies substantially above a normal operating range of the motor; and

a sensor coupled to the power line, the sensor monitoring a broadband impedance response to facilitate determining changes in capacitance between individual stator windings which is indicative of at least one of dielectric breakdown and chances in winding geometry associated with insulation of the stator windings, the changes in capacitance being manifested in the broadband impedance response.

2. The system of claim 1, wherein the sensor includes a voltage sensor for sensing a voltage on the power line, and a current sensor for sensing a current on the power line.

3. The system of claim 2, further comprising a processor for calculating the broadband impedance of the power line based on the sensed voltage and the sensed current.

4. The system of claim 1, wherein the signal generator is an X-10 generator.

5. The system of claim 1, further including a low pass filter coupled to the power line, the low pass filter serving to filter out high frequency components of signals passed to the motor via the power line prior to the introduction of the high frequency signal from the signal generator.

6. The system of claim 1, wherein the high frequency signal is between 20 kHz and 1 MHz.

7. The system of claim 1, comprising three power lines providing power to the motor, wherein each of the three power lines provides a different phase of power.

8. The system of claim 7, wherein the sensor is coupled to each of the three power lines.

9. A device for detecting stator winding damage in a motor during operation, comprising:

a high frequency signal generator coupled to a power line providing power to the motor, the high frequency signal generator introducing a high frequency signal on the power line, the high frequency signal being substantially above a normal operating range frequency of the motor;

a current sensor coupled to the power line for sensing the current passing through the power line;

a voltage sensor coupled to the power line for sensing the voltage on the power line; and

a processor for determining changes in capacitance between stator windings of the motor, the changes in capacitance being indicative of at least one of dielectric breakdown and changes in winding geometry associated with insulation of the stator windings;

wherein the processor makes such determination by analyzing a broadband impedance of the power line based on the sensed current and the sensed voltage.

10. The device of claim 9, wherein the high frequency signal generator is an X-10 chip.

11. The device of claim 10, wherein the power to the motor is provided via three power lines, each of the three power lines providing a different phase of power.

12. The device of claim 11, wherein the signal generator introduces the high frequency signal on each of the three power lines.

13. The device of claim 9, further comprising a low pass filter coupled to the power line, the low pass filter serving to filter out high frequency components of signals passed to the motor via the power line prior to the introduction of the high frequency signal.

14. The device of claim 9, wherein the high frequency signal is substantially 20 kHz or above.

15. A system for predicting stator winding damage in a motor during operation, comprising:

means for introducing a high frequency signal to a power line providing power to the motor, the high frequency signal being substantially above a normal operating range frequency of the motor;

means for analyzing a broadband impedance of the power line during introduction of the high frequency signal; and

means for determining changes in capacitance between stator windings of the motor based on the analyzed broadband impedance, the changes in capacitance being indicative of at least one of dielectric breakdown and changes in winding geometry associated with insulation of the stator windings.

16. The system of claim 15, wherein the means for introducing a high frequency signal is an X-10 signal generator.

17. The system of claim 16, wherein the means for determining an impedance includes:

a current sensor coupled to the power line for sensing a current passing through the power line;

a voltage sensor coupled to the power line for sensing a voltage on the power line; and

a processor coupled to the current sensor and the voltage sensor for calculating an impedance of the power line based on the sensed current and the sensed voltage.

18. A dynamoelectric machine diagnostic module adapted to be integrally mounted to a dynamoelectric machine and to facilitate predicting stator winding damage in the dynamoelectric machine during operation, comprising:

means for receiving current information from a current sensor;

means for receiving voltage information from a voltage sensor; and

a microprocessor operatively coupled to the means for receiving current information and the means for receiving voltage information, the microprocessor processing the current information and the voltage information to facilitate analyzing a broadband impedance of the machine during introduction of a high frequency signal in order to determine changes in capacitance between stator windings of the motor, the high frequency signal being substantially above a normal operating range frequency of the motor, the changes in capacitance being indicative of at least one of dielectric breakdown and changes in winding geometry associated with insulation of the stator windings.

19. The module of claim 18 further including a communication device adapted to enable the microprocessor to communicate with other devices.

20. The module of claim 18, wherein the machine is one of a DC brush motor, a do brushless motor, a synchronous motor, a stepper motor, and a switch reluctance motor.

21. The module of claim 18, wherein the module is integrally mounted in a conduit box that is thermally isolated from heat generated from the an outer surface of the machine in order to protect the module from the heat.

22. The module of claim 18, wherein the microprocessor calculates impedance based on the current information and the voltage information.

23. The module of claim 22, wherein the microprocessor compares the calculated impedance with a predetermined value to determine an operating condition of the motor.

24. A system for determining an operating state of a dynamoelectric machine during operation, comprising:

a host computer operatively coupled to a network;

a high frequency signal generator for generating high frequency signals to be introduced to power lines feeding the machine, the high frequency signals being substantially above normal operating range frequencies of the motor;

a voltage sensor coupled to the power line for sensing voltage on the power line;

a current sensor coupled to the power line for sensing current passing through the power line;

a microprocessor operatively coupled to the voltage sensor and the current sensor, the microprocessor processing the sensed voltage and the sensed current to facilitate analyzing an impedance of the power line at frequencies above about 0.3×

F_res, wherein F_res =the resonant frequency of the stator windings, the microprocessor determining changes in capacitance between stator windings of the motor, the changes in capacitance being indicative of at least one of dielectric breakdown and changes in winding geometry associated with insulation of the stator windings; and

a communications system adapted to enable communication between the microprocessor and the host computer.

25. The system of claim 24, wherein the signal generator is an X-10 chip.

26. The system of claim 24, wherein the machine is a motor.

27. A method of determining stator winding damage in a motor during operation, comprising the steps of:

introducing a high frequency signal on a power line providing power to the motor, the high frequency signal being substantially above a normal operating range frequency of the motor;

analyzing an impedance of the power line in conjunction with introducing the high frequency signal; and

determining changes in capacitance between stator windings of the motor based on the analyzed impedance, the changes in capacitance being indicative of at least one of dielectric breakdown and changes in winding geometry associated with insulation of the stator windings.

28. The method of claim 27, further including the steps of:

sensing a voltage of the power line during introduction of the high frequency signal; and

sensing a current on the power line.

30. The method of claim 27, wherein the step of introducing a high frequency signal includes using an X-10 signal generator.

31. The method of claim 27, further comprising a step of filtering out high frequency signals from the power line prior to the step of introducing the high frequency signal.

29. The method of 28 further including the step of calculating the impedance by a processor based on the sensed voltage and sensed current.

32. The method of step 27, wherein the high frequency signal is substantially in the range of 80-150 kHz.