Abstract: A method and system for the measurement of energy in an alternating-current motor drive containing a frequency converter or an equivalent stepless rotational speed regulator provided with semiconductor switches. In this regulator, the power taken by the motor drive from the mains is determined, and based on the power taken by the motor drive from the mains, the energy taken from the supply mains, especially the accumulated energy consumption after a given instant is determined.

Abstract: A method of arranging frequency converters in a cabinet including placing the frequency converters one above the other in a first section of the cabinet, and passing a cooled medium from a second section to a third section of the cabinet such that the cooled medium flows substantially across parts included in the respective frequency converters. Further, the second and third sections are on adjacent sides of the first section. The method also includes arranging supply voltage and load cabling connected to the frequency converters in at least one of the second or third sections of the cabinet.

Abstract: A method and an apparatus for compensating reactive power and/or harmonic currents in an alternating-current network by means of a frequency converter (1) feeding an alternating-current load (3), which frequency converter has a mains bridge (10) and at least one load bridge (11), said bridges being provided with controllable semiconductor switches. In the method, the reactive power and/or harmonic currents in the alternating-current network are measured, the load of the mains bridge of the frequency converter is measured, and the reactive power and/or harmonic currents in the alternating-current network are compensated by means of the frequency converter when the mains bridge is running at less than full capacity or has no load.

Abstract: A method and system for the measurement of energy in an alternating-current motor drive containing a frequency converter (10, 11) or an equivalent stepless rotational speed regulator provided with semiconductor switches, in which regulator the power taken by the electric drive from the mains is determined, and in which, based on the power taken by the electric drive from the mains, the energy taken from the supply mains, especially the accumulated energy consumption after a given instant is determined.

Abstract: Placement of the units of frequency converters, especially the power units (PU#21-PU #24, PU#31-PU#34) of frequency converters in a switch cabinet (21-23, 31-33) or equivalent, wherein the power units are placed one above the other in at least one section (22, 32) of the switch cabinet or equivalent, and wherein the cooling air or liquid circulation of the power units has been directed to flow substantially horizontally through their parts requiring cooling, in such manner that on at least one side of the section (22, 32) housing the power units is provided a section, such as a bay or an otherwise protected space, through which space/spaces cooling air or liquid is passed into the power units and likewise passed out.

Abstract: A method and an apparatus for compensating reactive power and/or harmonic currents in an alternating-current network by means of a frequency converter (1) feeding an alternating-current load (3), which frequency converter has a mains bridge (10) and at least one load bridge (11), said bridges being provided with controllable semiconductor switches. In the method, the reactive power and/or harmonic currents in the alternating-current network are measured, the load of the mains bridge of the frequency converter is measured, and the reactive power and/or harmonic currents in the alternating-current network are compensated by means of the frequency converter when the mains bridge is running at less than full capacity or has no load.