Abstract: A method and device of determining a fault condition in a synchronous motor including a rotor provided with damper bars and an end ring to which the damper bars are mechanically connected thereby forming a damper cage, wherein the method includes: obtaining a first measurement of an end ring current from a first location along the end ring, processing the first measurement to thereby obtain a processing result, and determining whether a fault condition is present in the synchronous motor based on the processing result.

Abstract: There is provided mechanisms for monitoring substation equipment. A method is performed by a SCADA system. The method comprises obtaining data/signal values of parameters monitored in the substation equipment. The method comprises associating each data/signal value with at least one attention indicator. The method comprises determining one attention indicator value for each of the attention indicators by processing those data/signal values that are associated with the respective attention indicators. All attention indicators for all monitored parameters have one and the same nominal attention indicator value acting as a threshold for abnormal behavior of the substation equipment. The method comprises providing an alert indication to a human machine interface (HMI) when at least one of the attention indicator values is above the nominal attention indicator value.

Abstract: A method for preventing a frequency component of a voltage from occurring in an electrical machine including the steps of: obtaining, either by measuring a voltage signal or a current signal from the electrical machine in time domain and transforming the measured signal into frequency domain, by simulating or deducing a first frequency component present in the electrical machine in absence of a grounding, the first frequency component representing a first undesired frequency higher than a limit frequency of 500 Hz; and providing the electrical machine with a first grounding at a grounding location, the first grounding including a resonant circuit resonating at the first undesired frequency. In order to get rid of harmful shaft voltages in the form of sharp voltage peaks at high frequencies, it is first necessary to determine at which undesired frequency or frequencies these voltage peaks occur.

Abstract: A rotor bar fault in a rotor of an electrical machine having a plurality of rotor bars and an end ring configured to short circuit the rotor bars. The method includes the steps of measuring a first temperature at a first end ring location, and measuring a second temperature at a second end ring location, the second end ring location being different from the first end ring location. As broken rotor bars cause a non-uniform temperature distribution in the end ring, the detection of rotor bar faults can be based on monitored temperatures at different end ring locations.

Abstract: A rotor bar fault in a rotor of an electrical machine having a plurality of rotor bars and an end ring configured to short circuit the rotor bars. The method includes the steps of measuring a first temperature at a first end ring location, and measuring a second temperature at a second end ring location, the second end ring location being different from the first end ring location. As broken rotor bars cause a non-uniform temperature distribution in the end ring, the detection of rotor bar faults can be based on monitored temperatures at different end ring locations.

Abstract: A method and device of determining a fault condition in a synchronous motor including a rotor provided with damper bars and an end ring to which the damper bars are mechanically connected thereby forming a damper cage, wherein the method includes: obtaining a first measurement of an end ring current from a first location along the end ring, processing the first measurement to thereby obtain a processing result, and determining whether a fault condition is present in the synchronous motor based on the processing result.

Abstract: A method for preventing a frequency component of a voltage from occurring in an electrical machine including the steps of: obtaining, either by measuring a voltage signal or a current signal from the electrical machine in time domain and transforming the measured signal into frequency domain, by simulating or deducing a first frequency component present in the electrical machine in absence of a grounding, the first frequency component representing a first undesired frequency higher than a limit frequency of 500 Hz; and providing the electrical machine with a first grounding at a grounding location, the first grounding including a resonant circuit resonating at the first undesired frequency. In order to get rid of harmful shaft voltages in the form of sharp voltage peaks at high frequencies, it is first necessary to determine at which undesired frequency or frequencies these voltage peaks occur.

Abstract: A method and system of determining an electro-mechanical fault condition in a synchronous machine having a stator, a rotor, and exciter. The method includes: a) obtaining an exciter current signal which is a measurement of an exciter current through stationary windings of the exciter, b) transforming the exciter current signal to obtain an exciter current frequency spectrum, and c) determining whether an electro-mechanical fault condition is present, and a type of the electro-mechanical fault condition, based on harmonic content related to the frequency of the stator, of the exciter current frequency spectrum.

Abstract: A method of determining a fault condition in a synchronous machine. The method includes a) obtaining a field current signal and a shaft voltage signal of the synchronous machine, b) transforming the field current signal and the shaft voltage signal to obtain a field current frequency spectrum and a shaft voltage frequency spectrum, and c) determining whether a fault condition is present, and in case a fault condition is present identifying a type of the fault condition, based on harmonic content of the field current frequency spectrum and harmonic content of the shaft voltage frequency spectrum, wherein c) includes comparing the harmonic content of the field current frequency spectrum with fault condition field current signature spectra and comparing the harmonic content of the shaft voltage frequency spectrum with fault condition shaft voltage signature spectra.

Abstract: A method and system of determining an electro-mechanical fault condition in a synchronous machine having a stator, a rotor, and exciter. The method includes: a) obtaining an exciter current signal which is a measurement of an exciter current through stationary windings of the exciter, b) transforming the exciter current signal to obtain an exciter current frequency spectrum, and c) determining whether an electro-mechanical fault condition is present, and a type of the electro-mechanical fault condition, based on harmonic content related to the frequency of the stator, of the exciter current frequency spectrum.

Abstract: A method for determining an undesired condition in an electrical drive system including an electrical machine and an electrical drive, wherein the method includes a) obtaining a measured signal of an electrical or mechanical parameter, b) obtaining a frequency spectrum of the measured signal, that contains a measured frequency component, c) determining whether the measured frequency component is within a predetermined distance from a trend line, which trend line is associated with only one specific frequency component of the electrical or mechanical parameter present during a specific undesired condition, d) on the condition that the measured frequency component is within the predetermined distance from the trend line increasing a counter associated with the trend line, e) repeating steps a) to d), wherein in case the counter reaches a predetermined number determining that the electrical drive system is subjected to the undesired condition associated with the trend line.

Abstract: A method of determining a fault condition in a synchronous machine. The method includes a) obtaining a field current signal and a shaft voltage signal of the synchronous machine, b) transforming the field current signal and the shaft voltage signal to obtain a field current frequency spectrum and a shaft voltage frequency spectrum, and c) determining whether a fault condition is present, and in case a fault condition is present identifying a type of the fault condition, based on harmonic content of the field current frequency spectrum and harmonic content of the shaft voltage frequency spectrum, wherein c) includes comparing the harmonic content of the field current frequency spectrum with fault condition field current signature spectra and comparing the harmonic content of the shaft voltage frequency spectrum with fault condition shaft voltage signature spectra.

Abstract: A method for determining an undesired condition in an electrical drive system including an electrical machine and an electrical drive, wherein the method includes a) obtaining a measured signal of an electrical or mechanical parameter, b) obtaining a frequency spectrum of the measured signal, that contains a measured frequency component, c) determining whether the measured frequency component is within a predetermined distance from a trend line, which trend line is associated with only one specific frequency component of the electrical or mechanical parameter present during a specific undesired condition, d) on the condition that the measured frequency component is within the predetermined distance from the trend line increasing a counter associated with the trend line, e) repeating steps a) to d), wherein in case the counter reaches a predetermined number determining that the electrical drive system is subjected to the undesired condition associated with the trend line.