Abstract: A method and device for assessing damage to a rolling bearing caused by bearing currents, in particular high-frequency bearing currents, in an electric machine which is electrically connected to an inverter, in particular to an inverter having a DC voltage link circuit, is described. The rolling bearing has a lubrication gap between an inner bearing ring and a rolling body and between an outer bearing ring and the rolling body. The method includes detecting the energy of an electric discharge event in the lubrication gaps, searching for a coincident event having a frequency above one GHz indicative of a damaging bearing current event, detecting a frequency of occurrence of discharge events, and evaluating the discharge events by correlating the frequency of occurrence and the energy of the discharge events.

Abstract: Electric arc discharges between bearing rings in a roller bearing are analyzed by setting a defined operating state based on rotational speed of the roller bearing, temperature of the roller bearing, an imbalance of the roller bearing causing vibrations, lubricants, axial/radial/tilt loads, tilting of the bearing rings relative to each other, pulse shape and pulse repetition rate of an applied electrical voltage, bearing play, and pre-existing damage to the roller bearing. A pulse-shaped electrical voltage between inner and outer bearing ring generates electric arc discharges, wherein for each electric arc discharge a characteristic value representative of energy, power, voltage and/or current and duration of the electric arc discharge is determined. Only those electric arc discharges are evaluated that have a qualifying value determined in accordance with at least one of the characteristic values greater than a predefined limit value.

Abstract: In a method for determining and/or monitoring the state of a roller bearing wherein during the operation of the roller bearing a sensor signal in the form of a sound emission signal is detected in a frequency band in the ultrasonic range, according to an embodiment of the invention shock pulses in the sensor signal are determined. As a result, electrical bearing currents in the roller bearing can be detected and damage to the bearing can therefore be avoided early.

Abstract: A rotor for a synchronous machine has a rotor axis which defines a rotor shaft. The rotor has a winding support which is arranged on the rotor shaft such that they rotate together, in such a way that it surrounds the rotor shaft in a center section with respect to the rotor axis. The winding support is fitted with a superconducting rotor winding. The rotor has a sleeve which at least radially surrounds the winding support and the rotor winding with respect to the rotor axis. The sleeve is formed integrally from a metal alloy, which is non-magnetic, has an electrical conductivity of at least 60% of the electrical conductivity of copper at 20° C., has a mechanical tensile strength of at least 250 N/mm2 at 200° C. and has a 0.2% proof stress of at least 200 N/mm2 at 200° C.

Abstract: A method and device for assessing damage to a rolling bearing caused by bearing currents, in particular high-frequency bearing currents, in an electric machine which is electrically connected to an inverter, in particular to an inverter having a DC voltage link circuit, is described. The rolling bearing has a lubrication gap between an inner bearing ring and a rolling body and between an outer bearing ring and the rolling body. The method includes detecting the energy of an electric discharge event in the lubrication gaps, searching for a coincident event having a frequency above one GHz indicative of a damaging bearing current event, detecting a frequency of occurrence of discharge events, and evaluating the discharge events by correlating the frequency of occurrence and the energy of the discharge events.

Abstract: Electric arc discharges between bearing rings in a roller bearing are analyzed by setting a defined operating state based on rotational speed of the roller bearing, temperature of the roller bearing, an imbalance of the roller bearing causing vibrations, lubricants, axial/radial/tilt loads, tilting of the bearing rings relative to each other, pulse shape and pulse repetition rate of an applied electrical voltage, bearing play, and pre-existing damage to the roller bearing. A pulse-shaped electrical voltage between inner and outer bearing ring generates electric arc discharges, wherein for each electric arc discharge a characteristic value representative of energy, power, voltage and/or current and duration of the electric arc discharge is determined. Only those electric arc discharges are evaluated that have a qualifying value determined in accordance with at least one of the characteristic values greater than a predefined limit value.

Abstract: A rotor for an electrical machine, in particular a synchronous machine has a rotor axis which defines a rotor shaft. The rotor has a winding support which is arranged on the rotor shaft such that they rotate together, in such a way that it surrounds the rotor shaft in a centre section with respect to the rotor axis. The winding support is fitted with a superconducting rotor winding. The rotor has a sleeve which at least radially surrounds the winding support and the rotor winding with respect to the rotor axis. At least in the area, in which it radially surrounds the winding support and the superconducting rotor winding, the sleeve is formed integrally from a metal alloy, which is non-magnetic, has an electrical conductivity of at least 60% of the electrical conductivity of copper at 20° C., has a mechanical tensile strength of at least 250 N/mm2 at 200° C. and has a 0.2% proof stress of at least 200 N/mm2 at 200° C.