Various embodiments include a DC switch for disconnecting a DC line. The switch may include: a power semiconductor switch arranged in a current path of the DC line; a first sensor for measuring the input and output voltages; a second sensor for measuring the current flowing through the DC line; and a controller for the power semiconductor switch. The control device is configured to: switch on the DC switch for a first time period; determine the input voltage present; determine the output voltage present at the end of the first time period; determine the current intensity present at the end of the first time period; and determine an inductance and/or capacitance from the determined values.