Abstract: A method and a corresponding appliance for measuring the output current of a frequency converter, the frequency converter including a network bridge that can be connected to an AC network, a controllable three-phase load bridge that can be connected to an AC load, and a DC intermediate circuit between them, the DC intermediate circuit including a filter capacitor that includes controllable semiconductor switches in each phase and that are controlled by pulse-width modulation, and in which the currents of the output phases are determined based on measured samples of the current of the filter capacitor of the DC intermediate circuit.

Abstract: A wiring arrangement and an appliance for limiting the harmonics of a current supplied to a frequency converter from an AC electricity supply network, which frequency converter can be connected to a three-phase AC electricity supply network, in which frequency converter is an uncontrolled network bridge (10) for rectifying the AC voltage of the AC electricity supply network, a DC intermediate circuit, in which is a filtering capacitor (CDC), and a load bridge (11) provided with power semiconductor switches for forming three-phase AC voltage (U, V, W), and which load bridge can be controlled with pulse-width modulation by means of a control unit, and in which DC intermediate circuit is a choke, in which is a choke part (L1, L2) arranged on both the positive and the negative pole, and in which wiring arrangement is an absorption circuit for limiting the harmonics of the current supplied from the AC electricity supply network, in which the absorption circuit is arranged in the DC intermediate voltage circuit,

Abstract: Method of and system for controlling the restart of an A.C. motor drive comprising an A.C. motor (4), a power converter (20, 21, 22) for stepless speed control of the A.C. motor and a load switch (3) arranged between the power converter and the A.C motor, wherein when the power converter (20, 21, 22) detects the output current to go below a predefined limit during the load switch opening it goes to a continuous output sensing mode, and when the output current goes above a predefined limit during the output sensing mode the power converter restarts automatically to a desired operating state.

Abstract: A wiring arrangement and an appliance for limiting the harmonics of a current supplied to a frequency converter from an AC electricity supply network, which frequency converter can be connected to a three-phase AC electricity supply network, in which frequency converter is an uncontrolled network bridge (10) for rectifying the AC voltage of the AC electricity supply network, a DC intermediate circuit, in which is a filtering capacitor (CDC), and a load bridge (11) provided with power semiconductor switches for forming three-phase AC voltage (U, V, W), and which load bridge can be controlled with pulse-width modulation by means of a control unit, and in which DC intermediate circuit is a choke, in which is a choke part (L1, L2) arranged on both the positive and the negative pole, and in which wiring arrangement is an absorption circuit for limiting the harmonics of the current supplied from the AC electricity supply network, in which the absorption circuit is arranged in the DC intermediate voltage circuit,

Abstract: Method and appliance for measuring the output current of a frequency converter, which frequency converter contains a network bridge (10) that can be connected to an AC network, a controllable three-phase load bridge (11) that can be connected to an AC load, and a DC intermediate circuit between them, which contains a filter capacitor, which load bridge contains controllable semiconductor switches in each phase, which are controlled by pulse-width modulation, and in which the currents of the output phases are determined by means of measured samples of the current of the filter capacitor of the DC intermediate circuit.