Abstract: A method controls an UPS with a system having: first and second terminals, a switch having: first and second switch terminals respectively connected to the first and second terminals; first and second thyristors connected between the first and second switch terminals in anti-parallel; and an inverter connected to the second terminal and the energy store. Switch current and a first potential at the first terminal are detected. In a first fault, where the first potential drops past a first rule and the switch current rises above a second rule: a second potential at the second switch terminal is set using the inverter so the switch current becomes zero. Then the switch current is compared with a second threshold, and if it is exceeded, a first check result is positive, otherwise it's negative. When positive, the second potential is reversed.

Abstract: A method controls an UPS with a system having: first and second terminals, a switch having: first and second switch terminals respectively connected to the first and second terminals; first and second thyristors connected between the first and second switch terminals in anti-parallel; and an inverter connected to the second terminal and the energy store. Switch current and a first potential at the first terminal are detected. In a first fault, where the first potential drops past a first rule and the switch current rises above a second rule: a second potential at the second switch terminal is set using the inverter so the switch current becomes zero. Then the switch current is compared with a second threshold, and if it is exceeded, a first check result is positive, otherwise it's negative. When positive, the second potential is reversed.

Abstract: The invention relates to an on-load tap changer (1) for controlling voltage, comprising semiconductor switching elements (61, 62, 71, 72), and to a method for controlling voltage for a variable transformer (2). The on-load tap changer (1) has a first load branch (6) and a second load branch (7) arranged parallel thereto. A partial winding (8) is arranged between the first and second load branches (6, 7). In the first load branch (6), a first semiconductor switching element (61) is provided upstream of the partial winding (8) and a second semiconductor switching element (62) is provided downstream of the partial winding (8). In the second load branch (7), a first semiconductor switching element (71) is provided upstream of the partial winding (8) and a second semiconductor switching element (72) is provided downstream of the partial winding (8).

Abstract: The invention relates to an on-load tap changer (1) for controlling voltage, comprising semiconductor switching elements (61, 62, 71, 72), and to a method for controlling voltage for a variable transformer (2). The on-load tap changer (1) has a first load branch (6) and a second load branch (7) arranged parallel thereto. A partial winding (8) is arranged between the first and second load branches (6, 7). In the first load branch (6), a first semiconductor switching element (61) is provided upstream of the partial winding (8) and a second semiconductor switching element (62) is provided downstream of the partial winding (8). In the second load branch (7), a first semiconductor switching element (71) is provided upstream of the partial winding (8) and a second semiconductor switching element (72) is provided downstream of the partial winding (8).