Abstract: A method for obtaining an estimate for a process quantity of a turbomachine comprises measuring (301) first process quantities and calculating (302) an estimate for a second process quantity, for example mass flow, on the basis of the measured first process quantities and a reference table of interrelations between process quantities prevailing in reference inlet conditions corresponding to a pre-defined inlet fluid temperature, a pre-defined inlet fluid pressure, and pre-defined fluid properties at the inlet. The reference table and the measured first process quantities represent such a set of data values that the estimate is obtainable on the basis of different sub-sets of the data values. Hence, the estimation task is over-posed in the sense that there is more data than necessary for obtaining the estimate. In the calculation of the estimate, more weight is given to such a part of the data which has a smaller error contribution.

Abstract: A machine comprises a rotor (101), a stator (102), main bearings (103), and safety bearings (104) for supporting the rotor in a situation where the main bearings are non-operating. When the rotor is supported by the main bearings, there are radial and axial clearances between the rotor and the safety bearings. A contact surface (107) of the rotor contacting the safety bearing in response to closure of the axial clearance is oblique with respect to a spatial plane perpendicular to a rotational axis of the rotor so that an angle (?) between the rotational axis and a normal of the contact surface at a point of contact between the rotor and the safety bearing is greater than zero and at most 10 degrees. The obliqueness of the contact surface eliminates at least partly an excitation for whirling motion when the rotor is supported by the safety bearings.

Abstract: A method for obtaining an estimate for a process quantity of a turbomachine comprises measuring (301) first process quantities and calculating (302) an estimate for a second process quantity, for example mass flow, on the basis of the measured first process quantities and a reference table of interrelations between process quantities prevailing in reference inlet conditions corresponding to a pre-defined inlet fluid temperature, a pre-defined inlet fluid pressure, and pre-defined fluid properties at the inlet. The reference table and the measured first process quantities represent such a set of data values that the estimate is obtainable on the basis of different sub-sets of the data values. Hence, the estimation task is over-posed in the sense that there is more data than necessary for obtaining the estimate. In the calculation of the estimate, more weight is given to such a part of the data which has a smaller error contribution.

Abstract: A rotor structure of a permanent magnet electrical machine and a method for manufacture of the rotor structure. The rotor structure has a shaft. An outer surface of the shaft is provided with a permanent magnet. A support collar encircles the permanent magnet. A protective piece is located between the outer surface of the shaft and an inner surface of the support collar and is arranged as an axial mechanical extension for the permanent magnet. The protective piece reduces local maximum values of forces forming between the support collar and the permanent magnet during rotation of the rotor.

Abstract: A rotor structure of a permanent magnet electrical machine and a method for manufacture of the rotor structure. The rotor structure has a shaft. An outer surface of the shaft is provided with a permanent magnet. A support collar encircles the permanent magnet. A protective piece is located between the outer surface of the shaft and an inner surface of the support collar and is arranged as an axial mechanical extension for the permanent magnet. The protective piece reduces local maximum values of forces forming between the support collar and the permanent magnet during rotation of the rotor.

Abstract: The invention is a compensator for minimizing circulatory current losses generated in a winding of an electric machine, the compensator comprising a frame part made of a magnetically conductive material and a winding formed in the frame part, the winding comprising at least one conductor having at least two sub-conductors; and at least one opening in said frame part. Said at least two sub-conductors extend through said at least one opening in such a way that the total current flowing through the opening is substantially zero, when a substantially equal current is led to the sub-conductors; and that at least two different sub-conductors are placed to extend through at least one opening. There is also disclosed an electric machine, the compensator being used in connection with the stator of the electric machine; and a method for forming a compensator to be used for minimizing circulatory current losses generated in a winding of an electric machine.

Abstract: The invention is a compensator for minimizing circulatory current losses generated in a winding of an electric machine, the compensator comprising a frame part made of a magnetically conductive material and a winding formed in the frame part, the winding comprising at least one conductor having at least two sub-conductors; and at least one opening in said frame part. Said at least two sub-conductors extend through said at least one opening in such a way that the total current flowing through the opening is substantially zero, when a substantially equal current is led to the sub-conductors; and that at least two different sub-conductors are placed to extend through at least one opening. There is also disclosed an electric machine, the compensator being used in connection with the stator of the electric machine; and a method for forming a compensator to be used for minimizing circulatory current losses generated in a winding of an electric machine.