General Electric Company

Accumetrics, Inc.

John M Reschovsky

Walter Whipple

John F Wolfinger

Abraham S Assa

Gerald P Hunt

Staci Jane Elaan

Walter Reisinger

A method and apparatus for fault detection of series diodes in rectifiers is disclosed, wherein the voltages across one or both of the individual diodes, and/or the voltage across the pair of diodes are measured to determine a ratio between two of those voltages. The ratio is then analyzed to determine if a fault (e.g., a short circuit or an open circuit) is present. In some embodiments, circuitry can be included to compensate for the normal variations in diode characteristics (e.g., reverse leakage current, reverse recovery charge) between the pair of series diodes to minimize the potential for erroneous fault detection.

Method and apparatus for fault detection of series diodes in rectifiers

An electrical conductor forming a grid only partially circumferentially surrounds the path of the outer portion of a rotatable member. The member has a magnet coupled thereto for influencing the grid to produce a signal indicative of vibration of the member whenever the magnet is within a predetermined distance of the grid. During the interval that the magnet does not influence the grid, a synthesis signal, indicative of vibration of the member during the previous influence portion of the revolution, is generated. The influence signal and the synthesis signal may be provided to processing apparatus for obtaining vibration information. Providing both an influence signal and a synthesis signal substantially simplifies processing apparatus that would otherwise be needed should only an essentially null signal be available during the interval in which the magnet does not influence the grid. In another embodiment, switching means coordinated with rotation of a plurality of members permits use of a plurality of partially circumferentially disposed grids for monitoring vibration of each of the plurality of members.

Apparatus and method for measuring vibration of a rotating member

An apparatus is provided for obtaining data from sensor measurements made on a body moving rotationally with respect to a stationary observer. Radio frequency energy is reactively coupled between an energy source fixed with respect to the observer and load varying means located on the moving body. The load variance is dependent upon measurement data provided by sensors located on the moving body. The variation in load is reflected back through the reactive coupler to a detector which is fixed with respect to the observer. The detector operates to provide signals indicative of the measurement data provided by the sensors. The apparatus of the present invention may be easily retrofitted to rotational devices such as turbines, motors and generators to provide relevant, continuous, on-line measurements of important parameters associated with such rotating systems. These parameters include such measurements as temperature, pressure, strain and torque. Because of the reflected load nature of the formation transmission, only a single coupling is provided and this coupling serves to carry both power and information signals.

Rotor measurement system using reflected load transmission

A multichannel data acquisition system for physical measurements on rotating members of operating machinery avoids slip rings and radio telemetry for data transfer by providing a capacitive coupling link between rotating and stationary members. Electronic circuitry mounted on the rotating member provides a pulse-code modulated signal containing the measured information for transmission through the capacitive coupling link. Power required to operate the rotating circuitry is inductively coupled from a stationary high-frequency source. The rotating circuitry includes a digital counter whose count is incremented by a momentary power interruption and whose digital output corresponds to a particular measuring range, allowing a range selection to be made during machinery operation.

Range selectable contactless data acquisition system for rotating

A self-calibrating subcarrier telemetry system for measuring strain on rotating members of a turbine under operating conditions. A rotor mounted portion of the system includes a strain gage transducer bridge excited by a subcarrier alternating current derived from an induced power source. The transducer bridge produces an output signal, amplitude modulated by the strain signal whereby the modulation shifts the strain signal into a higher frequency portion of the spectrum away from low-frequency noise related to the rotational speed of the turbine. A calibration signal is introduced by automatically unbalancing the bridge transducer periodically at a rate related to the subcarrier frequency. The strain signal is recovered in a stationary data reception portion of the system by a synchronous detector. A reference calibration signal is provided against which receiver gain is adjusted to achieve a null, leaving only the calibrated strain signal and achieving indpendence of variations in system gain. Nulling against the unipolar calibration reference further provides a means to distinguish tensile and compressive strain.

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Schenectady, NY, United States of America

John M Reschovsky