Abstract: A method and a photovoltaic inverter determines the system capacitance of a photovoltaic system relative to ground. The voltage required for the measurement can be provided by the intermediate circuit in the form of the intermediate circuit voltage, and the measuring device is designed to actuate an input short-circuit switch for short-circuiting the DC input with the AC disconnector open, as a result of which the intermediate circuit voltage can be applied to the DC input in the reverse direction, and the measuring device is configured to determine the system capacitance from the temporal waveform of the measured voltage after the switch of the voltage divider is closed.

Abstract: A method and a photovoltaic inverter for determining the insulation resistance of a photovoltaic system relative to ground are provided. The voltage required for the measurement can be provided by an intermediate circuit in the form of an intermediate circuit voltage and a measuring device is designed to actuate an input short-circuit switch for short-circuiting a DC input with an AC disconnector open, as a result of which the intermediate circuit voltage can be applied to the DC input in the reverse direction. The measuring device is configured to record measured voltages with a switch of a voltage divider open and closed, and to determine the insulation resistance from the measured values of the two measured voltages recorded with the switch of the voltage divider open and closed.

Abstract: The invention relates to a method and a photovoltaic inverter (2) for determining the insulation resistance (Riso) of a photovoltaic system (1) relative to ground (PE). According to the invention, the voltage required for the measurement can be provided by the intermediate circuit (6) in the form of the intermediate circuit voltage (UZk), and the measuring device (13) is designed to actuate an input short-circuit switch (SBoost) for short-circuiting the DC input (3) with the AC disconnector (8) open, as a result of which the intermediate circuit voltage (UZk) can be applied to the DC input (3) in the reverse direction, and the measuring device (13) is configured to record measured voltages (UM1, UM2) with the switch (Siso) of the voltage divider (14) open and closed, and to determine the insulation resistance (Riso) from the measured values of the two measured voltages (UM1, UM2) recorded with the switch (Siso) of the voltage divider (14) open and closed.

Abstract: A method and a photovoltaic inverter determines the system capacitance of a photovoltaic system relative to ground. The voltage required for the measurement can be provided by the intermediate circuit in the form of the intermediate circuit voltage, and the measuring device is designed to actuate an input short-circuit switch for short-circuiting the DC input with the AC disconnector open, as a result of which the intermediate circuit voltage can be applied to the DC input in the reverse direction, and the measuring device is configured to determine the system capacitance from the temporal waveform of the measured voltage after the switch of the voltage divider is closed.

Abstract: The invention relates to a method and to an apparatus for protecting transistors (S1, S3; S2, S4) arranged in at least one path, wherein transistors (S1, S3; S2, S4) connected in series to which an input voltage (Ue) is applied are arranged in a path (2), and the transistors (S1, S3; S2, S4) of a path are alternately switched between a conductive state and a blocking state in order to generate an output voltage (Ua) at the center of the path. In order to prevent both transistors (S1, S3; S2, S4) of a path from triggering, the blocking state of the second transistor (S3; S4) of the path is checked before switching a transistor (S1; S2) into the conductive state, and the switching is released by way of a signal generated during the check.