Patent ID: 7082374

Claim:
A measurement and evaluation method of energy consumption in an electrical drive, said electrical drive including a control unit and an AC motor, the method comprising the steps of: utilizing the data from the control unit related to the state of the AC motor so that at least in one predetermined measurement time period, at predetermined measurement intervals at the measurement points, the state data is read, and the measurement values of power and frequency are saved in the measurement register, calculating the energy consumption of the electrical drive at least in one predetermined measurement time period, defining the power value of a virtual AC motor that is fed by constant-frequency input current on the basis of the power and frequency values saved in the measurement register, calculating the energy consumption of the virtual electric motor fed by constant-frequency input current in said measurement time period, defining the energy consumption of an alternative control arrangement in said measurement time period, adding together the calculated energy consumptions of the virtual AC motor and the alternative control arrangement, and comparing the energy consumption of the electrical drive with the added total energy consumption of the virtual electric motor and the alternative control arrangement in order to evaluate the energy savings achieved by the electrical drive in the measurement time period in question.