Monitoring method and apparatus using high-frequency carrier
AssigneeMartin Marietta Energy Systems, Inc.
InventorHoward D. Haynes
Life of this patent
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Abstract
A method and apparatus for monitoring an electrical-motor-driven device by injecting a high frequency carrier signal onto the power line current. The method is accomplished by injecting a high frequency carrier signal onto an AC power line current. The AC power line current supplies the electrical-motor-driven device with electrical energy. As a result, electrical and mechanical characteristics of the electrical-motor-driven device modulate the high frequency carrier signal and the AC power line current. The high frequency carrier signal is then monitored, conditioned and demodulated. Finally, the modulated high frequency carrier signal is analyzed to ascertain the operating condition of the electrical-motor-driven device.
Claims22
A method for monitoring a machine which generates a first electrical signal which varies in accordance with machine operation, comprising the steps of:
- injecting a second high frequency carrier electrical signal onto the first electrical signal to produce a third, modulated carrier electrical signal;
- demodulating the third carrier electrical signal;
- and
- correlating characteristics of the demodulated carrier signal to machine operating conditions.
An apparatus for monitoring a machine which generates a first electrical signal which varies in accordance with machine operation, comprising:
- means for injecting a second high frequency carrier electrical signal onto the first electrical signal to produce a third, modulated carrier electrical signal;
- means for demodulating the third carrier electrical signal;
- and
- means, coupled to the demodulating means, for correlating characteristics of the demodulated carrier signal to machine operating conditions.
A method for monitoring an electrical-motor-driven device powered by an AC power line current, comprising the steps of:
- injecting a high frequency carrier signal onto said AC power line current, wherein electrical and mechanical characteristics of said electrical-motor-driven device modulate said high frequency carrier signal and said AC power line current to produce a modulated resultant current signal;
- high pass filtering said modulated resultant current signal;
- demodulating said filtered, modulated resultant current signal;
- and
- analyzing said modulated resultant current signal to ascertain the operating condition of said electrical-motor-driven device.
A method for monitoring a machine which generates a first electrical signal which varies in accordance with machine operation, comprising the steps of:
- injecting a second high frequency carrier electrical signal onto the first electrical signal to produce a third, modulated carrier electrical signal to produce a third, modulated carrier electrical signal;
- and
- correlating characteristics of the third, modulated carrier electrical signal to machine operating conditions.
Dependencies are inferred from the claim text.