System and method for monitoring the status of one or more components of an electrical machine

Abstract

A monitoring apparatus configured for monitoring a carbon brush of a brush holder assembly of an electrical machine. The monitoring apparatus may include a flexible sensor and a signal processing circuit for processing a signal received from the flexible sensor. The flexible sensor may have an electrical resistance that varies based on a radius of curvature of the flexible sensor, wherein the radius of curvature of the flexible sensor may be associated with a deflection of a spring providing a force to engage the carbon brush with a rotating component of the electrical machine. The signal processing circuit may be coupled to the sensor and may be configured to determine a measure of a wear state of the carbon brush using information about the variable resistance of the flexible sensor.

What is claimed is: 
     
       1. A monitoring apparatus for monitoring a carbon brush of a brush holder assembly of an electrical machine, the apparatus comprising:
 a sensor configured to move with a spring of the brush holder assembly, the sensor having an output that varies as a shape of the sensor varies, wherein the shape of the sensor changes in response to movement of the carbon brush in relation to a rotating component of the electrical machine; and 
 a signal processing circuit coupled to the sensor to receive the output, the signal processing circuit configured for determining a measure of a wear state of the carbon brush using output of the sensor, 
 wherein the signal processing circuit is positionable within a coiled portion of the spring. 
 
     
     
       2. The monitoring apparatus of claim  1  21, wherein the sensor has a first shape upon initial installation of the carbon brush in the electrical machine and a second shape after a particular amount of wear to the carbon brush. 
     
     
       3. The monitoring apparatus of  claim 1 , wherein the movement of the carbon brush is indicative of the wear state of the carbon brush and the sensor may be aligned along a plane after a particular amount of wear to the carbon brush. 
     
     
       4. The monitoring apparatus of claim  1  21, wherein the shape of the sensor that varies is a radius of curvature of the sensor that changes in response to movement of the carbon brush in relation to a rotating component of the electrical machine. 
     
     
       5. The monitoring apparatus of  claim 4 , wherein the sensor has a first radius of curvature upon initial installation of the carbon brush in the electrical machine and a second radius of curvature after a particular amount of wear to the carbon brush. 
     
     
       6. The monitoring apparatus of  claim 4 , wherein the output is a voltage output. 
     
     
       7. The monitoring apparatus of  claim 6 , wherein the voltage output varies as the radius of curvature of the sensor varies. 
     
     
       8. The monitoring apparatus of claim  1  21, wherein the sensor includes a flexible resistor and the output of the sensor varies in response to an electrical resistance of the flexible resistor changing due, at least in part, to changes in the shape of the sensor. 
     
     
       9. The monitoring apparatus of  claim 1 , wherein the signal processing circuit determines the measure of the wear state of the carbon brush by comparing the output of the sensor to at least one predetermined threshold value. 
     
     
       10. The monitoring apparatus of  claim 9 , wherein the at least one predetermined threshold value corresponds to a steady state measure of the output of the sensor. 
     
     
       11. The monitoring apparatus of  claim 1 , wherein the signal processing circuit determines the measure of the wear state of the carbon brush by comparing the output of the sensor to a first threshold value and determines a measure of a wear state of the rotating component of the electrical machine by comparing the output of the sensor to a second threshold value. 
     
     
       12. A brush holder assembly, the assembly comprising:
 a brush holder for receiving and positioning a carbon brush in relation to a rotating component of an electrical machine; 
 a spring mounted to the brush holder, the spring for providing a force to a carbon brush received in the brush holder such that the carbon brush engages the rotating component of the electrical machine; 
 a sensor positioned between the spring and the brush holder, the sensor having an output that varies as a shape of the sensor varies, wherein the shape of the sensor is representative of based on a physical position and/or movement of a carbon brush received in the brush holder; and 
 a wear state monitor in electrical communication with the sensor, the wear state monitor positioned within a coiled portion of the spring, the wear state monitor for determining a measure of a wear state of the carbon brush using the output of the sensor. 
 
     
     
       13. The assembly of  claim 12 , wherein the brush holder includes a mounting beam and the sensor is positioned between the mounting beam and the spring. 
     
     
       14. The assembly of claim  12  22, wherein the shape of the sensor that varies is a radius of curvature of the sensor that changes in response to movement of the carbon brush in relation to a rotating component of the electrical machine. 
     
     
       15. The assembly of  claim 14 , wherein the output is a voltage output. 
     
     
       16. The assembly of  claim 15 , wherein the voltage output varies as the radius of curvature of the sensor varies. 
     
     
       17. The assembly of claim  12  22, wherein the sensor includes a flexible resistor and the output of the sensor varies in response to an electrical resistance of the flexible resistor changing due, at least in part, to changes in the shape of the sensor. 
     
     
       18. The assembly of  claim 12 , wherein the wear state monitor is further configured to determine a wear state of the rotating component of the electrical machine using the output of the sensor. 
     
     
       19. A brush holder assembly having an integral sensor for monitoring a wear state of a carbon brush or a rotating component of an electrical machine, the brush holder assembly comprising:
 a brush holder having a mounting beam; 
 a carbon brush positioned in the brush holder; 
 a spring coupled to the brush holder, the spring for providing a force to engage the carbon brush with a rotating component of the electrical machine; 
 a sensor positioned between the spring and the mounting beam, the sensor having an output that changes as a change in radius of curvature of the sensor changes; 
 an indicator for providing an indication of the wear state of at least one of the carbon brush and the rotating component of the electrical machine based, at least in part, on the output of the sensor. 
 
     
     
       20. The brush holder assembly of  claim 19 , further comprising:
 a communication circuit, the communication circuit configured communicate information about the wear state of at least one of the carbon brush and the rotating component of the electrical machine to a site monitor proximate to the electrical machine. 
 
     
     
       21. The monitoring apparatus of claim 1, wherein the output of the sensor varies as a shape of the sensor varies, wherein the shape of the sensor changes in response to movement of the carbon brush. 
     
     
       22. The brush holder assembly of claim 12, wherein the output of the sensor varies as a shape of the sensor varies, wherein the shape of the sensor changes in response to movement of the carbon brush. 
     
     
       23. A monitoring apparatus having a sensor for monitoring a wear state of a carbon brush of a brush holder assembly of an electrical machine, the monitoring apparatus comprising:
 a sensor attachable to a spring of the brush holder assembly, wherein the sensor is configured to move with the spring;   a wear state monitor positionable within a coiled portion of the spring, wherein the wear state monitor is communicatively coupled to the sensor to obtain information about the wear state of the carbon brush based on movement of the spring; and   a power source disposed within the coiled portion of the spring to provide power to the wear state monitor.   
     
     
       24. The monitoring apparatus of claim 23, wherein the wear state monitor includes a cylindrical body designed to be captured within the coiled portion of the spring. 
     
     
       25. The monitoring apparatus of claim 24, wherein the wear state monitor includes one or more ribs used to ensure the wear state monitor remains mounted within the coiled portion of the spring. 
     
     
       26. The monitoring apparatus of claim 23, wherein the wear state monitor includes a communication circuit, the communication circuit for communicating information about a wear state of the carbon brush. 
     
     
       27. The monitoring apparatus of claim 26, wherein the communication circuit is capable of communicating via one or more wireless technologies. 
     
     
       28. The monitoring apparatus of claim 27, wherein the communication circuit is configured to wirelessly communicate the wear state of the carbon brush to a site monitor proximate to the electrical machine. 
     
     
       29. The monitoring apparatus of claim 23, wherein the wear state monitor includes a temperature sensor. 
     
     
       30. The monitoring apparatus of claim 23, wherein the wear state monitor is configured to identify a characteristic of a vibration of the carbon brush. 
     
     
       31. The monitoring apparatus of claim 23, wherein the wear state monitor includes an energy harvester. 
     
     
       32. A system for monitoring a wear state of a carbon brush of a brush holder assembly mounted on an electrical machine, the system comprising:
 a wear state monitor positionable within a coiled portion of a spring urging the carbon brush into engagement with a rotating component of the electrical machine; and   a site monitor configured to receive a signal from the wear state monitor indicative of a wear state of the carbon brush;   wherein the wear state monitor includes a power source disposed within the coiled portion of the spring to provide power to the wear state monitor.   
     
     
       33. The system of claim 32, wherein the wear state monitor is communicatively coupled to a sensor to obtain information about the wear state of the carbon brush. 
     
     
       34. The system of claim 32, wherein the site monitor is configured to receive the signal from the wear state monitor wirelessly. 
     
     
       35. The system of claim 32, wherein the wear state monitor is configured to monitor a vibration of the carbon brush and the site monitor is configured to notify a user of excess vibration of the carbon brush. 
     
     
       36. The system of claim 32, wherein the wear state monitor includes a temperature sensor and the site monitor is configured to notify a user of excess heating of the brush holder assembly. 
     
     
       37. The system of claim 32, wherein the wear state monitor includes an energy harvester. 
     
     
       38. A method for monitoring a wear state of a carbon brush of a brush holder assembly mounted on an electrical machine, the method comprising:
 obtaining a signal from a sensor attached to a spring of the brush holder assembly, the spring urging the carbon brush into engagement with a rotating component of the electrical machine, wherein the signal is proportional to linear movement of the carbon brush relative to a brush holder of the brush holder assembly surrounding the carbon brush;   processing the signal with a wear state monitor positioned within the coiled portion of the spring to determine a wear state of the carbon brush, wherein the wear state monitor includes a power source disposed within the coiled portion of the spring to provide power to the wear state monitor; and   communicating the wear state of the carbon brush to a site monitor in proximity to the electrical machine.   
     
     
       39. The method of claim 38, further comprising:
 displaying an indication of the wear state of the carbon brush on a display of the site monitor.   
     
     
       40. The method of claim 38, further comprising:
 displaying a predicted life expectancy of the carbon brush on a display of the site monitor.   
     
     
       41. The method of claim 38, wherein the signal varies based on movement of the sensor with the spring. 
     
     
       42. The method of claim 38, further comprising:
 monitoring a vibration of the carbon brush with the wear state monitor.   
     
     
       43. The method of claim 38, wherein the wear state monitor includes an energy harvester. 
     
     
       44. A brush holder assembly for monitoring a wear state of a carbon brush of an electrical machine, the brush holder assembly comprising:
 a carbon brush;   a spring associated with the carbon brush, the spring applying a force to a top surface of the carbon brush to engage the carbon brush with a rotating component of the electrical machine; and   a wear state monitor positioned within a coiled portion of the spring;   wherein the wear state monitor includes a power source disposed within the coiled portion of the spring to provide power to the wear state monitor.   
     
     
       45. The brush holder assembly of claim 44, wherein the wear state monitor includes a cylindrical body designed to be captured within the coiled portion of the spring. 
     
     
       46. The brush holder assembly of claim 44, wherein the wear state monitor includes a communication circuit, the communication circuit for communicating information about a wear state of the carbon brush. 
     
     
       47. The brush holder assembly of claim 44, wherein the wear state monitor includes one or more environmental sensors, wherein the one or more environmental sensors includes a temperature sensor. 
     
     
       48. The brush holder assembly of claim 44, wherein the wear state monitor is configured to identify a characteristic of a vibration of the carbon brush. 
     
     
       49. The brush holder assembly of claim 44, wherein the wear state monitor includes an energy harvester.