Abstract: Systems and methods are disclosed for on-line monitoring of the condition of insulation in electrical devices employing a differential current sensor. In certain embodiments a monitor that can be fitted to existing electrical devices by attachment of the sensor to a pair of phase cables is provided. In other embodiments, an electrical device configured with an insulation monitor is provided.

Abstract: A system (100, 200) is presented. The system includes a fluid lifting device (102, 202) located inside a well (106, 206), and comprising an electrical motor (108, 208), a three phase cable (114, 214) for coupling the fluid lifting device to a power source (112, 212), at least one high sensitivity differential current transformer (104, 203, 204) for generating imbalance signals (128, 227) representative of an imbalance current in at least one of the electrical motor and the three phase cable, wherein the at least one high sensitivity differential current transformer is disposed such that the at least one high sensitivity differential current transformer surrounds at least a portion of the three phase cable, and a processing subsystem (136, 236) for monitoring the health of at least one of the fluid lifting device and the three phase cable based on the imbalance signals.

Abstract: Systems and methods are disclosed for calibration and compensation of on-line current transformers. In certain embodiments, a method to calibrate a single current transformer by use of an AC injected current is provided. In other embodiments, a method to calibrate and compensate multiple current transformers using a single AC injected current is provided. In further embodiments, a system for calibration and compensation of multiple current transformers is provided. The adequate frequency of the injected current as well as other characteristics for adequate use in some embodiments is provided.

Abstract: A fault detection system for a wind turbine includes a doubly-fed induction generator (DFIG). The DFIG includes a wye-ring configured for at least three electrical phases. The fault detection system includes a data acquisition system including at least three sensors. Each sensor of said at least three sensors is configured to electrically couple with and measure a respective voltage of each phase of the at least three electrical phases of the wye-ring. The fault detection system further includes an alert system coupled to said data acquisition system. The alert system is configured to apply a Fourier transform to the respective measured voltages of each phase of the at least three electrical phases of the wye-ring. The alert system is further configured to provide an indication of a condition of the wye-ring based upon the transformed measured voltages.

Abstract: A method implemented using a processor based device includes obtaining a measured electrical signal from an electrical device coupled to a mechanical device and generating a signal signature representative of a fault in the mechanical device based on the measured electrical signal. The method also includes determining a diagnostic parameter based on a harmonic frequency of the signal signature and determining the fault in the mechanical device based on the diagnostic parameter.

Abstract: A system and method for monitoring a motor of a vehicle system monitor operating conditions of the vehicle system and determine whether the operating conditions of the vehicle system match designated operating conditions. Responsive to determining that the operating conditions of the vehicle system that are monitored match the designated operating conditions, an electrical signature representative of an electric current supplied to the motor of the vehicle system is examined and damage to one or more of the motor of the vehicle system or a mechanical coupling of the motor to one or more of a wheel or axle of the vehicle system is identified based on the electrical signature that is examined.

Abstract: A method implemented using a controller based device includes receiving a measured electrical signal from an electrical device of an electromechanical device and receiving a measured vibration signal from a mechanical device of the electromechanical device, coupled to the electrical device. The method further includes determining a first signal signature based on the measured electrical signal and determining a second signal signature based on the measured vibration signal. The method also includes determining a diagnostic parameter based on the first signal signature and the second signal signature and determining a fault in the mechanical device based on the diagnostic parameter.

Abstract: A system including a non-intrusive capacitive voltage sensor configured to couple to an insulator surrounding a metal conductor, wherein the non-intrusive capacitive voltage sensor is configured to produce a voltage signal indicative of a voltage in the metal conductor, and a monitor-controller system configured to receive the voltage signal from the non-intrusive capacitive voltage sensor, wherein the monitor-controller system is configured to use the voltage signal to monitor or control a machine.

Abstract: A method for estimating a speed of an induction motor includes applying a voltage to the induction motor and measuring a current of the induction motor. A current fast fourier transform (FFT) of the current is then determined and a slip of the induction motor is calculated based on the current FFT. A speed of the induction motor is then estimated based on the slip of the induction motor.

Abstract: Systems and methods are disclosed for on-line monitoring of the condition of the stator insulation of an AC motor or an electric generator. In certain embodiments, the system includes a transformer surrounding each pair of input and output cables associated with a given phase of power provided to the AC motor or generated by the electric generator. In another embodiment, a transformer surrounds the three input cables (for an AC motor) or the three output cables (for an electric generator) that correspond to phases of the AC motor or electric generator. In both embodiments, the transformers generate voltages that may be used to monitor leakage currents associated with the cables. A microcontroller monitors the voltages generated by the transformers and determines the condition of the stator insulation of the AC motor or the electric generator based on the voltages.

Abstract: A method for estimating a speed of an induction motor includes applying a voltage to the induction motor and measuring a current of the induction motor. A current fast fourier transform (FFT) of the current is then determined and a slip of the induction motor is calculated based on the current FFT. A speed of the induction motor is then estimated based on the slip of the induction motor.

Abstract: A system configured to monitor an operating electrical device includes a testing channel coupled to the device. The device is coupled to an electric power source through at least one electric power transmission channel. The power source is configured to transmit electric power at a first frequency. The testing channel is coupled to the power transmission channel. The system also includes a signal generator coupled to the testing channel. The signal generator is configured to inject testing signals into the testing channel at a second frequency that is greater than the first frequency. The system further includes at least one apparatus magnetically coupled to the power transmission channel. The magnetically coupled apparatus is configured to present a first impedance to the electric power at the first frequency and present a second impedance to the test signals at the second frequency. The second impedance is greater than the first impedance.

Abstract: A method of detecting faults in a wind turbine generator based on current signature analysis is disclosed herein. The method includes acquiring a set of electrical signals representative of an operating condition of a generator. Further, the electrical signals are processed to generate a normalized spectrum of electrical signals. A fault related to a gearbox or bearing or any other component associated with the generator is detected based on analyzing the current spectrum.

Abstract: A system including a non-intrusive capacitive voltage sensor configured to couple to an insulator surrounding a metal conductor, wherein the non-intrusive capacitive voltage sensor is configured to produce a voltage signal indicative of a voltage in the metal conductor, and a monitor-controller system configured to receive the voltage signal from the non-intrusive capacitive voltage sensor, wherein the monitor-controller system is configured to use the voltage signal to monitor or control a machine.

Abstract: A method for detection of rotor bar faults in an electric machine is provided. The method includes acquiring electrical signals from the electric machine that are representative of the operative condition of the machine. The symmetrical components from the electrical signals are eliminated by squaring an instantaneous value of each data point from the electrical signals and summing the squared values. The method further includes the step of eliminating discontinuities in the electrical signals by applying a window function to compute weighted representation of the squared values. Furthermore, the method includes the step of normalizing the weighted representation to obtain spectral information. The faults in the rotor bar are detected by analyzing the spectral information obtained after normalization.

Abstract: A current transformer is provided. The current transformer comprises an inner magnetic core having a central opening, an outer sense core circumscribing the inner magnetic core, at least one pair of conductors extending through the central opening and positioned symmetrically with respect to a center point of the inner magnetic core, and one or more coils disposed on the inner magnetic core, the outer sense core, or both, in a magnetically balanced configuration relative to a magnetic neutral axis of the inner magnetic core.

Abstract: A method implemented using a controller based device includes receiving a measured electrical signal from an electrical device of an electromechanical device and receiving a measured vibration signal from a mechanical device of the electromechanical device, coupled to the electrical device. The method further includes determining a first signal signature based on the measured electrical signal and determining a second signal signature based on the measured vibration signal. The method also includes determining a diagnostic parameter based on the first signal signature and the second signal signature and determining a fault in the mechanical device based on the diagnostic parameter.

Abstract: A method implemented using a processor based device includes obtaining a measured electrical signal from an electrical device coupled to a mechanical device and generating a signal signature representative of a fault in the mechanical device based on the measured electrical signal. The method also includes determining a diagnostic parameter based on a harmonic frequency of the signal signature and determining the fault in the mechanical device based on the diagnostic parameter.

Abstract: Systems and methods are disclosed for on-line monitoring of the condition of the stator insulation of an AC motor or an electric generator. In certain embodiments, the system includes a transformer surrounding each pair of input and output cables associated with a given phase of power provided to the AC motor or generated by the electric generator. In another embodiment, a transformer surrounds the three input cables (for an AC motor) or the three output cables (for an electric generator) that correspond to phases of the AC motor or electric generator. In both embodiments, the transformers generate voltages that may be used to monitor leakage currents associated with the cables. A microcontroller monitors the voltages generated by the transformers and determines the condition of the stator insulation of the AC motor or the electric generator based on the voltages.

Abstract: A system configured to monitor an operating electrical device includes a testing channel coupled to the device. The device is coupled to an electric power source through at least one electric power transmission channel. The power source is configured to transmit electric power at a first frequency. The testing channel is coupled to the power transmission channel. The system also includes a signal generator coupled to the testing channel. The signal generator is configured to inject testing signals into the testing channel at a second frequency that is greater than the first frequency. The system further includes at least one apparatus magnetically coupled to the power transmission channel. The magnetically coupled apparatus is configured to present a first impedance to the electric power at the first frequency and present a second impedance to the test signals at the second frequency. The second impedance is greater than the first impedance.