Abstract: A partial discharge coupler for detecting partial discharges in a conductor includes a frequency dependent network, a differential amplifier and a frequency selective coupling component. The frequency dependent network includes a first filter component, a fuse component and a load component, typically coupled together in series with reference to a first ground. The first filter component filters the high voltage, low frequency alternating current signal carried by the conductor from the load component and passes high frequency partial discharge pulse signals to the load component. The frequency selective coupling component couples in series between the differential amplifier and the load component. The output of the differential amplifier is configured to provide an output that is isolated from the ground connection for communicating detected partial discharge signals to partial discharge test equipment.

Abstract: The claimed invention provides a blade vibration measuring system comprising a blade, a transmitter, a target with non parallel edges located on the blade shroud and a receiver. The present invention also provides a blade adapted for measuring blade vibration. Furthermore, the claimed invention provides a method for monitoring blade vibration.

Abstract: A method and system for monitoring the operating conditions of an electric generator. The system includes a triad sensor array formed within a predetermined section of a fiber optic conductor. The triad sensor array is formed of a group of sensors including a first sensor including a Bragg grating for producing a first signal representative of strain in a stator bar of the generator, a second sensor including a Bragg grating for producing a second signal representative of temperature in the stator bar, and a third sensor including a Bragg grating for producing a third signal representative of vibration amplitude in the stator bar.

Abstract: A method of matching sensors in a multi-probe blade vibration monitor for a turbine. The method includes providing at least two probes mounted in a casing of the turbine adjacent to a rotating blade structure of the turbine. Targets are provided on radially outer portions of the blade structure. Each of the probes includes a sensor generating signals corresponding to target passing events, and a set of synchronous harmonics of the rotational speed of the rotor are produced for each sensor. The position of the sensors is adjusted such that the sets of harmonics of the sensors are substantially matched, indicating that the positions of the sensors are matched.

Abstract: A marker pulse discriminator monitor that enables filtering of partial discharge pulses for monitoring the condition of a generator in a power plant system. The monitor detects partial discharge pulses emanating from the generator and includes a plurality of first modules connected to respective isophase buses adjacent to the generator. Each of the first modules generate a marker pulse in response to a partial discharge pulse. The monitor also includes an analyzer unit connected to the isophase buses adjacent to a step-up transformer. The analyzer unit receives each partial discharge pulse and each marker pulse and determines a differential value corresponding to a difference between a time of arrival of a partial discharge pulse and a time of arrival of a corresponding marker pulse to identify partial discharge pulses originating at the generator and to identify the isophase bus associated with the corresponding partial discharge pulse.

Abstract: A method of matching sensors in a multi-probe blade vibration monitor for a turbine. The method includes providing at least two probes mounted in a casing of the turbine adjacent to a rotating blade structure of the turbine. Targets are provided on radially outer portions of the blade structure. Each of the probes includes a sensor generating signals corresponding to target passing events, and a set of synchronous harmonics of the rotational speed of the rotor are produced for each sensor. The position of the sensors is adjusted such that the sets of harmonics of the sensors are substantially matched, indicating that the positions of the sensors are matched.

Abstract: A method for identifying an unfolded non-synchronous blade vibration frequency in blades on a rotating rotor using a plurality of probes spaced from each other about the rotor. A set of data is acquired from the probes during a predetermined number of rotor revolutions and is processed using a Fourier analysis to generate an output representative of frequencies and phase shift angles corresponding to blade vibrations. The phase shift angles are used to identify a subharmonic for a blade vibration frequency to provide an output identifying the vibration frequency. A space dispersion and time dispersion of probes is described to increase the accuracy of the subharmonic determination using the phase shift angles.

Abstract: A method for predicting a blade structure failure within a coupled blade structure including a plurality of blades supported for rotation on a rotor and a shroud structure coupling the blades. The method includes the steps of determining displacements of a plurality of predetermined circumferential locations on the shroud structure during rotation of the blade row, where the displacements are provided as a function of time relative to the periodic rotation of the shroud structure for time intervals that are integer multiples of rotor rotation. A signal characteristic related to vibrational mode and a nodal diameter of the shroud structure is derived based on the displacements of the circumferential locations on the shroud structure.

Abstract: A method and apparatus for monitoring vibrations in a blade structure of a turbine including generating signals from a probe located adjacent to a radial outer edge of the blade structure to provide signals corresponding to vibrations at predetermined locations along the tips of the blades. A leading edge of a blade tip is detected during a blade tracking operation, and a known location along the length of the blade tips is monitored during a vibration measurement operation. The measurement operation may be performed simultaneously with the tracking operation to provide measurements as the axial location of the blades change during transitional modes of operation of the turbine.

Abstract: A method of monitoring vibrations in a blade structure of a turbine including generating signals from a sensor located adjacent to a radial outer edge of the blade structure to sense passage of targets located on the blade structure. The sensor is mounted eccentrically and the signals are obtained with the sensor located at different angular positions. In a first aspect of the invention, the signals from the sensor are used to determine a target slope angle of a target on a first turbine blade during operation of the turbine. In a second aspect of the invention, the signals from the sensor are used to position the sensor in response to a sensed variation in the axial position of the target on the first turbine blade.

Abstract: A method and apparatus for monitoring blade vibrations in a turbine engine having blade tip target portions associated with blades. An illumination conduit including a plurality of optical fibers conveys light from a light source to a transmission end of the optical fibers where the light is focused to define an axially elongated projected image. The blade tip target portions pass through the projected image and reflect light to a receptor array defined by receptor ends of a plurality of optical fibers forming an imaging conduit for conveying the reflected light to a sensor array. An imaging end of the imaging conduit radiates an image onto the sensor array that is identical to the reflected light image received at the receptor array to track tangential and axial movement of a predetermined point on the target portion.

Abstract: A method and apparatus for monitoring blade vibrations in a turbine engine having blade tip target portions associated with blades. An illumination conduit including a plurality of optical fibers conveys light from a light source to a transmission end of the optical fibers where the light is focused to define an axially elongated projected image. The blade tip target portions pass through the projected image and reflect light to receptor ends of a plurality of optical fibers defining a detection conduit for conveying the reflected light to a processor. The transmission ends and receptor ends of the optical fibers are configured as a narrow rectangle to define a probe end for receiving reflected light at different axial locations along the probe end, and to detect blade passing events defined by passage of either or both a blade leading edge and a blade trailing edge.

Abstract: A partial discharge coupler for detecting partial discharges in a conductor includes a frequency dependent network, a differential amplifier and a frequency selective coupling component. The frequency dependent network includes a first filter component, a fuse component and a load component, typically coupled together in series with reference to a first ground. The first filter component filters the high voltage, low frequency alternating current signal carried by the conductor from the load component and passes high frequency partial discharge pulse signals to the load component. The frequency selective coupling component couples in series between the differential amplifier and the load component. The output of the differential amplifier is configured to provide an output that is isolated from the ground connection for communicating detected partial discharge signals to partial discharge test equipment.

Abstract: A method and system for monitoring the operating conditions of an electric generator. The system includes a triad sensor array formed within a predetermined section of a fiber optic conductor. The triad sensor array is formed of a group of sensors including a first sensor including a Bragg grating for producing a first signal representative of strain in a stator bar of the generator, a second sensor including a Bragg grating for producing a second signal representative of temperature in the stator bar, and a third sensor including a Bragg grating for producing a third signal representative of vibration amplitude in the stator bar.

Abstract: A method of measuring vibration in a bladed rotor structure with a vibration monitor. The vibration monitor includes a sensor for sensing passage of the sensor targets on radially outer portions of the blade structure, and the sensor generates signals corresponding to target passing events. An excitation structure is provided including at least one air jet for providing an excitation force to the blade structure. The blade structure is rotated about an axis of rotation and the air jet is driven in a circular path about the axis of rotation at a different rotational speed to apply a non-synchronous excitation force to the blade structure.

Abstract: A method for measuring the differential emissivity between two sites on the surface of a body and the temperature of the two sites. The method includes a plurality of measurements of the infrared radiation arising from each of the two sites under a number of different conditions. Some of the measurements include irradiation by external infrared radiation at a known wavelength and intensity. The infrared radiation arising from each of the sites may include emitted radiation, reflected ambient radiation, and reflected external radiation. Additionally, the temperature determined using the method described can be used to calibrate infrared imaging devices used to inspect the entire body.

Abstract: A marker pulse discriminator monitor that enables filtering of partial discharge pulses for monitoring the condition of a generator in a power plant system. The monitor detects partial discharge pulses emanating from the generator and includes a plurality of first modules connected to respective isophase buses adjacent to the generator. Each of the first modules generate a marker pulse in response to a partial discharge pulse. The monitor also includes an analyzer unit connected to the isophase buses adjacent to a step-up transformer. The analyzer unit receives each partial discharge pulse and each marker pulse and determines a differential value corresponding to a difference between a time of arrival of a partial discharge pulse and a time of arrival of a corresponding marker pulse to identify partial discharge pulses originating at the generator and to identify the isophase bus associated with the corresponding partial discharge pulse.

Abstract: A method for identifying an unfolded non-synchronous blade vibration frequency in blades on a rotating rotor using a plurality of probes spaced from each other about the rotor. A set of data is acquired from the probes during a predetermined number of rotor revolutions and is processed using a Fourier analysis to generate an output representative of frequencies and phase shift angles corresponding to blade vibrations. The phase shift angles are used to identify a subharmonic for a blade vibration frequency to provide an output identifying the vibration frequency. A space dispersion and time dispersion of probes is described to increase the accuracy of the subharmonic determination using the phase shift angles.

Abstract: A method for measuring the differential emissivity between two sites on the surface of a body and the temperature of the two sites. The method includes a plurality of measurements of the infrared radiation arising from each of the two sites under a number of different conditions. Some of the measurements include irradiation by external infrared radiation at a known wavelength and intensity. The infrared radiation arising from each of the sites may include emitted radiation, reflected ambient radiation, and reflected external radiation. Additionally, the temperature determined using the method described can be used to calibrate infrared imaging devices used to inspect the entire body.

Abstract: Electrical generators used for power generation typically operate at high voltage. The High operating voltage results in a severe electrical stress environment for the generator conductor insulation system. The high electrical stress cal lead to a phenomena such as corona, partial discharge and arcing that can cause damage to the insulation and conductors. Disclosed is a novel method and system of detecting partial discharge activity within an electric generator. The method employs at least two Rogowski loops non-contactingly surrounding individual iso-phase bus conductors, where the loops are wired in differential mode to detect fast moving electrical pulses indicative of partial discharge.