Abstract: The present invention is concerned with a method for diagnosing the state of electromechanical systems in which electrical rotating machinery is used on the basis of analysis of impedance estimated from at least two currents and two voltages, measured during an operation of the electromechanical system. The method may be especially useful in the condition monitoring of electric motors and generators. The invention combines the information from both the voltage and current signals measurable at the motor terminals. Specifically, the measurements of voltage and current from two or more phases of a polyphase electrical machine are combined to estimate the impedance of the machine, impedance being the resistance to the flow of current that a circuit exhibits when a voltage is applied to it.

Abstract: An electric machine including a closed chamber with a wall and enclosing a stator, a rotor and a first fluid and a heat exchanging unit stretching from the chamber through the wall to a fluid transporting passage. The heat exchanging unit includes conduits provided in a loop, containing a working fluid and equipped with evaporator channels and condenser channels, first heat transfer elements inside the chamber for transferring heat from the first fluid to the working fluid via the evaporator channels and second heat transfer elements in the passage for transferring heat out of the working fluid via the condenser channels to a second fluid, a first fluid propagating unit inside the chamber forcing the first fluid to circulate and a second fluid propagating unit in the passage forcing the second fluid to flow past the second heat transfer element.

Abstract: A method for identifying a fault condition in an electrical machine in which at least a stator or a rotor has parallel winding branches is disclosed. A measurement is carried out for obtaining a set of circulating current values between two parallel winding branches of which each winding branch includes a single coil. A frequency analysis is applied on the set of circulating current values to obtain at least one frequency component. A fault condition of the electrical machine is determined on the basis of the at least one frequency component.

Abstract: A device for installing a modular crawler into an air gap of rotating electrical machinery and removing the crawler from the air gap has a reconfigurable handle attached to a curved head made from metallic material. The crawler is magnetically attached to the curved head when it is desired to insert the crawler into the air gap or remove the crawler from the air gap. The head can be rolled in the field into the curvature needed to match the stator's inner surface so that the installation device can easily be inserted in the air gap. The handle has several joints that can be adjusted in the field as needed for the best reachability. A camera is mounted on the curved head so that an operator can see the interface region between the curved head, crawler and air gap.

Abstract: A missing stator slot wedge in an electrical machine can be detected by analyzing a current spectrum of the machine in a high frequency area. A current spectrum is provided from a current measurement, and values of the current spectrum in the high frequency area used to determine whether a stator slot wedge is missing or not. The conclusion can be based on values of a relative current amplitude IdB or on presence of certain harmonics in the high frequency area.

Abstract: An electric machine including a closed chamber with a wall and enclosing a stator, a rotor and a first fluid and a heat exchanging unit stretching from the chamber through the wall to a fluid transporting passage. The heat exchanging unit includes conduits provided in a loop, containing a working fluid and equipped with evaporator channels and condenser channels, first heat transfer elements inside the chamber for transferring heat from the first fluid to the working fluid via the evaporator channels and second heat transfer elements in the passage for transferring heat out of the working fluid via the condenser channels to a second fluid, a first fluid propagating unit inside the chamber forcing the first fluid to circulate and a second fluid propagating unit in the passage forcing the second fluid to flow past the second heat transfer element.

Abstract: A missing stator slot wedge in an electrical machine can be detected by analysing a current spectrum of the machine in a high frequency area. A current spectrum is provided from a current measurement, and values of the current spectrum in the high frequency area used to determine whether a stator slot wedge is missing or not. The conclusion can be based on values of a relative current amplitude IdB or on presence of certain harmonics in the high frequency area.