Systems, methods, and apparatus for monitoring a machine

1. A method for monitoring a machine, the method comprising:

providing an electrical signal for transmission to and into a component of the machine;

monitoring a capacitance associated with the electrical signal in the component;

determining an increase in the monitored capacitance as the component of the machine moves towards another component of the machine;

determining that the increase in the monitored capacitance exceeds a threshold value;

detecting a potential rub condition for the component of the machine based at least in part on the determination that the increase in the monitored capacitance exceeds the threshold value; and

determining a severity associated with the potential rub condition based at least in part on a length of time for which the increase in the monitored capacitance exceeds the threshold value.

2. The method of claim 1 , wherein the machine comprises a turbine.

3. The method of claim 1 , wherein the electrical signal comprises an alternating current voltage signal comprising a voltage of approximately one to approximately two volts.

4. The method of claim 1 , further comprising:

monitoring an impedance associated with the electrical signal, and detecting a rub condition based at least in part on determining a decrease in the monitored impedance.

5. The method of claim 4 , further comprising determining a severity associated with the detected rub condition based at least in part on a length of time for which the monitored impedance falls outside of an expected range of impedance values.

6. The method of claim 1 , wherein the electrical signal comprises an electrical signal with a frequency of approximately one kilohertz to approximately 50 kilohertz.

7. The method of claim 1 , wherein monitoring the electrical signal in the component of the machine comprises monitoring the component for an electrical signal having a frequency that is within a predetermined frequency range.

8. A system for monitoring a machine, the system comprising:

a signal generator configured to provide an electrical signal that is transmitted to and into at least one component of the machine;

one or more detection devices configured to detect a capacitance associated with the electrical signal in the at least one component; and

at least one processor configured to:

detect an increase in the capacitance as the component of the machine moves toward another component of the machine;

determine that the increase in the capacitance exceeds a threshold value;

detect, based at least in part on the determination that the increase in the capacitance exceeds the threshold value comparison, the occurrence of a potential rub condition for the component; and

determining a severity associated with the potential rub condition based at least in part on a length of time for which the increase in capacitance exceeds the threshold value.

9. The system of claim 8 , wherein the machine comprises a turbine.

10. The system of claim 8 , wherein the electrical signal comprises an alternating current voltage signal comprising a voltage of approximately one to approximately two volts.

11. The system of claim 8 , wherein the at least one processor is further configured to:

monitor an impedance associated with the electrical signal; and

detect the occurrence of a rub condition based at least in part on detecting a decrease in the monitored impedance.

12. The system of claim 8 , wherein the at least one processor is further configured to determine a severity associated with the detected rub condition based at least in part on a length of time for which the monitored impedance falls outside of an expected range of impedance values.

13. The system of claim 8 , wherein the electrical signal comprises an electrical signal with a frequency of approximately one kilohertz to approximately 50 kilohertz.

14. The system of claim 8 , wherein the one or more detection devices are operable to detect electrical signals that fall within a predetermined frequency range.

15. A method for monitoring a machine, the method comprising:

transmitting an alternating current voltage signal to and into at least one component of the machine;

monitoring a capacitance associated with the signal;

detecting an increase in the monitored capacitance as the component of the machine moves towards another component of the machine;

determining that the increase in the monitored capacitance exceeds a threshold value;

detecting, based at least in part on the determination that the increase in the monitored capacitance exceeds the threshold value, the occurrence of a potential rub condition for the component; and

determining a severity associated with the potential rub condition based at least in part on a length of time for which the increase in the capacitance exceeds the threshold value.

16. The method of claim 15 , wherein the alternating current voltage signal comprises a voltage of approximately one to approximately two volts.

17. The method of claim 15 , further comprising:

monitoring an impedance associated with the signal, and

detecting a rub condition based at least in part on determining a decrease in the monitored impedance.

18. The method of claim 15 , further comprising determining a severity associated with the identified rub condition based at least in part on a length of time for which the determined impedance falls outside of an expected range of impedance values.