Device for connecting a single-phase active load to a three-phase network

Abstract

The invention relates to the field of power engineering and can be used in cases where the load is active and single-phase, for example, an electric heater, and there is a symmetrical three-phase network that cannot be loaded with a single-phase load due to a violation of its symmetry.The device, according to the invention, comprises terminals for connecting a single-phase active load (5) and a resistor (7), connected in series, which, in turn, are connected to terminals for connecting phases A and C of a three-phase network (1). An inductor (3) and a first thyristor unit (2), connected in series, are connected between the terminals for connecting phases A and B of the three-phase network (1). A capacitor (4) and a second thyristor unit (6), connected in series, are connected between the terminals for connecting phases C and B of the three-phase network (1). To the resistor (7) is connected a rectifier with a filter (8), the output of which is connected to the first input of a comparator (9), and to its second input is connected a linearly varying voltage generator (10). The output of the comparator (9) is connected by means of a differentiating unit (11) to the first input of a trigger (12). The device further comprises a pulse generator (13), the output of which is connected via the first input of an electronic switch (14) to the first input of a pulse counter (16), the output of which is connected to the first input of a control unit (17), and its outputs are connected to the control inputs of the first (2) and second (6) thyristor units. The output of the trigger (12) is connected to the second input of the electronic switch (14). The output of the pulse generator (13) is also connected to a frequency divider (15), the output of which is connected to the second input of the trigger (12), the reset input of the linearly varying voltage generator (10), the second input of the pulse counter (16) and the second input of the control unit (17).