Testing device

A testing device for establishing the presence of high voltage at a component (1) which carries high voltage is provided with a coupling part (2) which has a coupling electrode (2.1) coupled capacitively to the component (1). The coupling electrode (2.1) delivers a measurement current which is evaluated by a signal-processing circuit (5). As long as the measurement current exceeds a maximum current value for display, the signal-processing circuit (5) generates a display signal as an indication of the presence of high voltage. In this case, the signal-processing circuit (5) is permanently connected to the coupling electrode (2). In order to test that the coupling circuit is capable of functioning properly, a testing circuit (7) is connected in parallel to the input (8) of the signal-processing circuit (5). If the display goes out, a fault in the coupling part (2) can be deduced.