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 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 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 detecting vibrations of a shaft of an electrical machine includes measuring at least one of a shaft voltage and a shaft current and analyzing the measured at least one of the shaft voltage and the shaft current so as to determine the vibrations. In addition, an apparatus for detecting vibrations of a shaft of an electrical machine includes a first grounding device disposed at a first point on the shaft on a first side of the electrical machine and a second grounding device disposed at a second point of the shaft on a second side of the electrical machine. The second grounding device is configured to measure at least one of a shaft voltage and a shaft current.

Abstract: An apparatus and a method for monitoring and/or analysis of electrical machines during operation, wherein the electrical machine has at least one generator with a shaft and drive means for driving this shaft, wherein the shaft is grounded at the first end of the generator, and wherein a measurement unit for measurement of shaft voltage and/or shaft current as a function of time is provided on the shaft at the second end of the generator. An apparatus such as this allows the combined and simultaneous measurement of various fault states by supplying signals for the shaft voltage and/or the shaft current to an analysis unit, wherein the analysis unit allows combined and simultaneous analysis of at least two potential fault states of the electrical machine. Simultaneous cross-relationships between the individual measurement results of individual fault states may be provided so as to allow a clearer and more reliable diagnosis of critical states, not possible when individual phenomena are considered separately.

Abstract: An apparatus and a method for monitoring and/or analysis of electrical machines during operation, wherein the electrical machine has at least one generator with a shaft and drive means for driving this shaft, wherein the shaft is grounded at the first end of the generator, and wherein a measurement unit for measurement of shaft voltage and/or shaft current as a function of time is provided on the shaft at the second end of the generator. An apparatus such as this allows the combined and simultaneous measurement of various fault states by supplying signals for the shaft voltage and/or the shaft current to an analysis unit, wherein the analysis unit allows combined and simultaneous analysis of at least two potential fault states of the electrical machine. Simultaneous cross-relationships between the individual measurement results of individual fault states may be provided so as to allow a clearer and more reliable diagnosis of critical states, not possible when individual phenomena are considered separately.

Abstract: A method for detecting vibrations of a shaft of an electrical machine includes measuring at least one of a shaft voltage and a shaft current and analyzing the measured at least one of the shaft voltage and the shaft current so as to determine the vibrations. In addition, an apparatus for detecting vibrations of a shaft of an electrical machine includes a first grounding device disposed at a first point on the shaft on a first side of the electrical machine and a second grounding device disposed at a second point of the shaft on a second side of the electrical machine. The second grounding device is configured to measure at least one of a shaft voltage and a shaft current.

Abstract: The present invention relates to a method, an apparatus and a computer program for inspecting laminated iron cores (1) of electrical machines for interlamination shorts, in which the laminated iron core (1) is magnetized by means of an auxiliary winding, and the iron surface is scanned by means of at least one measurement coil arrangement (2) with a downstream measurement device. In this case, unique and quantifiable localization of interlamination shorts is achieved by using both the phase (8) and the amplitude (7) of the electrical signal which is induced in the at least one measurement coil arrangement (2), in combined form.

Abstract: A protective and monitoring apparatus (20, 23) for monitoring and reducing shaft currents and shaft voltages on the generator shaft (19) of a generator (16) which produces electrical power, which protective and monitoring device (20, 23) is connected between a contact apparatus (21, 24), which makes contact with the generator shaft (19), and a grounding connection (22, 25) and comprises a parallel circuit formed by a resistance and a capacitance, with one end of the parallel circuit (26, 27) being connected to the contact apparatus (21, 24) and its other end being connected to the grounding connection (22, 25), said parallel circuit being protected against overvoltages on the generator shaft (19) and means (31) being provided for bridging the parallel circuit (26, 27) when an overvoltage occurs.

Abstract: The present invention relates to a method, an apparatus and a computer program for inspecting laminated iron cores (1) of electrical machines for interlamination shorts, in which the laminated iron core (1) is magnetized by means of an auxiliary winding, and the iron surface is scanned by means of at least one measurement coil arrangement (2) with a downstream measurement device. In this case, unique and quantifiable localization of interlamination shorts is achieved by using both the phase (8) and the amplitude (7) of the electrical signal which is induced in the at least one measurement coil arrangement (2), in combined form.

Abstract: A protective and monitoring apparatus (20, 23) for monitoring and reducing shaft currents and shaft voltages on the generator shaft (19) of a generator (16) which produces electrical power, which protective and monitoring device (20, 23) is connected between a contact apparatus (21, 24), which makes contact with the generator shaft (19), and a grounding connection (22, 25) and comprises a parallel circuit formed by a resistance and a capacitance, with one end of the parallel circuit (26, 27) being connected to the contact apparatus (21, 24) and its other end being connected to the grounding connection (22, 25), said parallel circuit being protected against overvoltages on the generator shaft (19) and means (31) being provided for bridging the parallel circuit (26, 27) when an overvoltage occurs.

Abstract: An arrangement for detecting winding shorts in a rotor winding of an electrical machine having a drive shaft with a drive end directly connected to ground and a measuring element provided at the non-drive end of the drive shaft for recording the shaft voltage between the machine shaft and ground. The voltage measuring element produces an output corresponding to the shaft voltage, which is applied to an analysis unit. The analysis unit evaluates the even or fractional harmonic content of the shaft voltage and outputs an alarm signal in the event that the even or fractional harmonic content exceeds a predetermined value.

Abstract: In order to detect interlamination shorts (8 ) in the case of laminated core stacks, the core stack (1) is magnetized with an auxiliary winding. The iron surface (15) is scanned with a measuring coil arrangement (5) comprising two electrically separated, mechanically interlinked coils (6, 7). The output signals from the coils are compared with each other in a downstream measuring instrument (9); in the case of an interlamination short, the fault current through the short-circuited laminations will induce in the coils different, phase-shifted voltages which make it possible to infer the position and size of the interlamination shorts.

Abstract: An arrangement for reducing voltages appearing in turbosets, wherein in addition to a grounding brush (7) on the drive end (DE), another (18) grounding brush is provided on the nondrive end (NDE) and is connected to ground (5) by an RC element (19,20). In this way, when grounding brush (7) on the drive end malfunctions, static charges and alternating frequency currents are reliably discharged.The currents flowing on the nondrive end and the voltages appearing between grounding brush (18) and ground (5) further allow reliable statements to be made about the operational capability and operational safety of the shaft grounding.