Abstract: A Rogowski coil assembly (1) for measurement of high frequency electrical currents includes coil segments (3) disposed in series with retrospective impedance influence reduction coupling.

Abstract: In an excitation device for stators of generators for high-induction measurement, the greatest possible compensation of the reactive power requirement is achieved. Depending on the size and energy requirement of the generator, a number of individual excitation modules with a corresponding number of individual excitation windings are provided, wherein a minimum necessary total excitation current can be supplied by superimposing the individual currents of the excitation windings.

Abstract: A method and an apparatus are described for detection of interlaminar laminate shorts in the laminated stator core of electrical machines, in which the laminated stator core (4) is subjected to an externally applied field current (2) or field voltage (V), and the short-circuit magnetic field (Bshort) induced by short-circuit currents (5) is measured with the assistance of a sensor coil (S1) which is arranged in the gap in the machine and probes this gap. Improved identification of laminate shorts, in particular even of small laminate shorts with small short-circuit currents, is possible in that a field current (2) and a field voltage (V) are applied which have a waveform which differs significantly from a sinusoidal shape, in particular with a periodic character, and have significant harmonic components in the high frequency range. By way of example, a waveform in the form of a square-wave curve is proposed.

Abstract: A method is provided for monitoring and/or analysis of electrical machines during operation. An electrical machine has at least one generator with a shaft, an exciter system and drive device that drives the shaft. In this case, a first signal, which describes a voltage across a rotor winding, and a second signal, which describes a current flowing through the rotor winding, are measured simultaneously. The two signals are supplied to an analysis unit. The signals are split into individual frequency components in the analysis unit. The impedance of the rotor winding is then determined in order to identify fault states in the electrical machine.

Abstract: A method is disclosed for monitoring shaft current (Iw) and/or insulation of the shaft of an electrodynamic machine, wherein susceptibility to interference can be reduced. A shaft voltage (Uw) and associated shaft current (Iw) are measured, and a relationship is determined from measurement results for the shaft voltage (Uw) and the shaft current (Iw) for the electrodynamic machine. The shaft voltage (Uw) can be monitored to monitor the shaft current (Iw), the shaft current (Iw) being deduced from the monitored shaft voltage (Uw) based on a determined relationship between the shaft voltage (Uw) and the associated shaft current (Iw).

Abstract: A method for monitoring an electrodynamic machine a stator and a rotor arrangement mounted along a rotatable shaft. The rotor arrangement is disposed within the stator and forms an air gap between the rotor arrangement and the stator. At least one sensor is disposed in the air gap and/or within the stator. Measurement signals are detected that are dependent on a magnetic field produced by the electrodynamic machine. The measurement signals are used as a basis for detecting oscillations of the shaft.

Abstract: In an excitation device for stators of generators for high-induction measurement, the greatest possible compensation of the reactive power requirement is achieved. Depending on the size and energy requirement of the generator, a number of individual excitation modules with a corresponding number of individual excitation windings are provided, wherein a minimum necessary total excitation current can be supplied by superimposing the individual currents of the excitation windings.

Abstract: A worn brush monitoring system for monitoring a plurality of brushes of an electrical machine comprises a plurality of mounted flags configured to be in moveable communication relative to a wear of each of the plurality of brushes and an electrical recording circuit. The electrical recording circuit includes at least one impedance device configured to provide impedance data, at least one switch having a contact plate interactable with at least two of the plurality of mounted flags at different points along a length of the contact plate and an impedance dependent on the length of the contact plate, and a recording device configured to detect changes in electrical characteristics in the electrical recording circuit resulting from changes in a switch state, the switch state defined by the interaction between the mounted flags and the electrical recording circuit, as a result of brush wear.

Abstract: A switch for a brush wear monitoring recording circuit for monitoring wear of at least one brush, the switch having an open and a closed state, comprises a fixed part including a switch plate having a switch face and a moving part including a capacitive flag disposed on a brush so as to move the capacitive flag corresponding to a brush wear movement in a brush wear direction and a capacitive plate having a capacitive face, wherein the capacitive face and the switch face are disposed parallel to each other and provide capacitance to the switch, and further wherein the capacitive flag is disposed on the brush so as to bring the capacitive face and the switch face in proximity to each other so as to face each other and increase capacitance, thereby changing the switch state.

Abstract: An apparatus is disclosed for monitoring brushes, such as slipring or commutator brushes, on electrical machines. At least one electronic sensor is configured to be arranged in or on a brush apparatus of an electrical machine such that an electrical supply power can be locally drawn directly from an electromagnetic environment of the brush apparatus. The apparatus can transmit measurement data detected by it by electromagnetic radiation to an indication device.

Abstract: A method for detecting turn-to turn faults in a laminate stack of a stator of an electrical machine or a generator includes magnetizing the stator using an auxiliary coil and an auxiliary current so as to form a magnetic field. The magnetic field is measured using a pickup device including at least two detectors disposed in at least two respective different radial positions with respect to a rotor axis so as to provide at least two signals corresponding to the magnetic field at the respective radial positions. The method includes evaluating and comparing a magnitude and/or a phase angle of the signals so as to determine a relative magnitude and/or relative phase angle by subtraction in order to detect turn-to-turn faults. Relative differences in the at least two signals are recorded. Also a device for performing the method.

Abstract: A method is provided for monitoring and/or analysis of electrical machines during operation. An electrical machine has at least one generator with a shaft, an exciter system and drive device that drives the shaft. In this case, a first signal, which describes a voltage across a rotor winding, and a second signal, which describes a current flowing through the rotor winding, are measured simultaneously. The two signals are supplied to an analysis unit. The signals are split into individual frequency components in the analysis unit. The impedance of the rotor winding is then determined in order to identify fault states in the electrical machine.

Abstract: A method for monitoring an electrodynamic machine a stator and a rotor arrangement mounted along a rotatable shaft. The rotor arrangement is disposed within the stator and forms an air gap between the rotor arrangement and the stator. At least one sensor is disposed in the air gap and/or within the stator. Measurement signals are detected that are dependent on a magnetic field produced by the electrodynamic machine. The measurement signals are used as a basis for detecting oscillations of the shaft.

Abstract: A switch for a recording circuit used to determine brush wear of an electrical brush comprises a flag having a first end and a second end defining distal ends of the flag. The flag is mounted on the electrical brush at the first end so as to move in unison with brush wear while being in electrical communication with the electrical brush and has a piercing feature on the second end. The switch further comprises a contact plate arrange relative to the flag so as to bring the flag in contact with the contact plate at a predetermined brush wear and includes an inner conductive core encased by a cover forming an outer layer of the contact plate, wherein the piercing feature is configured to penetrate the cover and to contact the conductive core to cause electrically continuous contact between the flag and the contact plate and close the switch.

Abstract: A method and an apparatus are described for detection of interlaminar laminate shorts in the laminated stator core of electrical machines, in which the laminated stator core (4) is subjected to an externally applied field current (2) or field voltage (V), and the short-circuit magnetic field (Bshort) induced by short-circuit currents (5) is measured with the assistance of a sensor coil (S1) which is arranged in the gap in the machine and probes this gap. Improved identification of laminate shorts, in particular even of small laminate shorts with small short-circuit currents, is possible in that a field current (2) and a field voltage (V) are applied which have a waveform which differs significantly from a sinusoidal shape, in particular with a periodic character, and have significant harmonic components in the high frequency range. By way of example, a waveform in the form of a square-wave curve is proposed.

Abstract: A method is disclosed for monitoring shaft current (Iw) and/or insulation of the shaft of an electrodynamic machine, wherein susceptibility to interference can be reduced. A shaft voltage (Uw) and associated shaft current (Iw) are measured, and a relationship is determined from measurement results for the shaft voltage (Uw) and the shaft current (Iw) for the electrodynamic machine. The shaft voltage (Uw) can be monitored to monitor the shaft current (Iw), the shaft current (Iw) being deduced from the monitored shaft voltage (Uw) based on a determined relationship between the shaft voltage (Uw) and the associated shaft current (Iw).

Abstract: A method for determining a short circuit between at least two stator laminates in an electrical machine having a rotor mounted on a shaft and a stator, includes rotating the rotor on the shaft relative to the stator so to pass a magnetic stator flux, varying over time, through the stator, determining, during the rotation, a measurement variable sensitive to a short-circuit current caused by the magnetic stator flux between the at least two stator laminates, and determining the magnetic stator flux. In addition, a theoretical model is provided describing a relationship between the magnetic stator flux and the measurement value or an auxiliary variable derived from the measurement value, and the measurement variable or the auxiliary variable is compared with the theoretical model. A device for carrying out a method for determining a short circuit is also provided.

Abstract: A method and apparatus for detection of spark activity in an electrical machine having a shaft, wherein at least one of the shaft voltage and the shaft current is measured and analyzed for components which are characteristic of spark activity. The method uses the shaft voltages and/or shaft currents which are normally generally regarded only as being damaging has been found to be accurate and to be suitable for long-term monitoring of spark activities such as brush sparking, spark erosion, spark flashovers between parts of the shaft bearings and can be implemented physically very easily and in a reliable manner, since the existing grounding devices are used.

Abstract: A worn brush monitoring system for monitoring a plurality of brushes of an electrical machine comprises a plurality of mounted flags configured to be in moveable communication relative to a wear of each of the plurality of brushes and an electrical recording circuit. The electrical recording circuit includes at least one impedance device configured to provide impedance data, at least one switch having a contact plate interactable with at least two of the plurality of mounted flags at different points along a length of the contact plate and an impedance dependent on the length of the contact plate, and a recording device configured to detect changes in electrical characteristics in the electrical recording circuit resulting from changes in a switch state, the switch state defined by the interaction between the mounted flags and the electrical recording circuit, as a result of brush wear.

Abstract: A switch for a recording circuit used to determine brush wear of an electrical brush comprises a flag having a first end and a second end defining distal ends of the flag. The flag is mounted on the electrical brush at the first end so as to move in unison with brush wear while being in electrical communication with the electrical brush and has a piercing feature on the second end. The switch further comprises a contact plate arrange relative to the flag so as to bring the flag in contact with the contact plate at a predetermined brush wear and includes an inner conductive core encased by a cover forming an outer layer of the contact plate, wherein the piercing feature is configured to penetrate the cover and to contact the conductive core to cause electrically continuous contact between the flag and the contact plate and close the switch.