A method for evaluating a speed or a frequency of a motor controlled by a frequency converter, the method comprising: measuring (101, 102, 103), by a voting-based speed analysis unit, first, second and third phase currents of three-phase electric power fed from the frequency converter to the motor; forming, by the voting-based speed analysis unit, first, second and third current measurement pairs, wherein the first current measurement pair comprises the first phase current and the second phase current, the second current measurement pair comprises the second phase current and the third phase current and the third current measurement pair comprises the third phase current and the first phase current; estimating (104, 105, 106), by the voting-based speed analysis unit, the speed or frequency of the motor separately based on each pair of the first, second and third current measurement pairs to produce respective first, second and third estimates for the speed or frequency of the motor; applying, by the voting-based speed analysis unit, a voting logic to the first, second and third estimates for the speed or frequency of the motor, wherein the voting logic employs, in the voting, one or more pre-defined criteria for the speed or frequency of the motor and is based on one of the following: a one out of three, 1oo3, voting architecture, a two out of three, 2oo3, voting architecture, a three out of three, 3oo3, voting architecture, a one out of three diagnosed, 1oo3D, voting architecture, a two out of three diagnosed, 2oo3D, voting architecture and a three out of three diagnosed, 3oo3D, voting architecture; and feeding, by the voting-based speed analysis unit, an output of the voting logic to a safety logic for controlling triggering of at least one safety function of the frequency converter based on the output of the voting logic and on one or more pre-defined safety criteria, wherein the output of the voting logic comprises a final estimate for the speed or frequency of the motor and an indication whether or not said final estimate is valid according to the voting logic. measuring (101, 102, 103), by a voting-based speed analysis unit, first, second and third phase currents of three-phase electric power fed from the frequency converter to the motor; forming, by the voting-based speed analysis unit, first, second and third current measurement pairs, wherein the first current measurement pair comprises the first phase current and the second phase current, the second current measurement pair comprises the second phase current and the third phase current and the third current measurement pair comprises the third phase current and the first phase current; estimating (104, 105, 106), by the voting-based speed analysis unit, the speed or frequency of the motor separately based on each pair of the first, second and third current measurement pairs to produce respective first, second and third estimates for the speed or frequency of the motor; applying, by the voting-based speed analysis unit, a voting logic to the first, second and third estimates for the speed or frequency of the motor, wherein the voting logic employs, in the voting, one or more pre-defined criteria for the speed or frequency of the motor and is based on one of the following: a one out of three, 1oo3, voting architecture, a two out of three, 2oo3, voting architecture, a three out of three, 3oo3, voting architecture, a one out of three diagnosed, 1oo3D, voting architecture, a two out of three diagnosed, 2oo3D, voting architecture and a three out of three diagnosed, 3oo3D, voting architecture; and feeding, by the voting-based speed analysis unit, an output of the voting logic to a safety logic for controlling triggering of at least one safety function of the frequency converter based on the output of the voting logic and on one or more pre-defined safety criteria, wherein the output of the voting logic comprises a final estimate for the speed or frequency of the motor and an indication whether or not said final estimate is valid according to the voting logic. a one out of three, 1oo3, voting architecture, a two out of three, 2oo3, voting architecture, a three out of three, 3oo3, voting architecture, a one out of three diagnosed, 1oo3D, voting architecture, a two out of three diagnosed, 2oo3D, voting architecture and a three out of three diagnosed, 3oo3D, voting architecture; and feeding, by the voting-based speed analysis unit, an output of the voting logic to a safety logic for controlling triggering of at least one safety function of the frequency converter based on the output of the voting logic and on one or more pre-defined safety criteria, wherein the output of the voting logic comprises a final estimate for the speed or frequency of the motor and an indication whether or not said final estimate is valid according to the voting logic.