A control unit for an elevator installation, said control unit having an elevator car movable between floors along an elevator shaft and a drive unit for moving the elevator car between the floors, the control unit being realized for interacting with a safety circuit which is in particular laid through the elevator shaft and which is realized by a plurality of safety switches which are interconnected in series and which are switchable between an open state interrupting the travel operation and a closed state enabling the travel operation as a function of safety-related operating conditions of the elevator installation, the safety circuit, in particular at least one safety switch (4, 18), being capable of being bypassed sectionally by contacting a maintenance bridge, having intermediate taps (6, 21, 22, 23, 24, 25) for tapping an intermediate voltage, said intermediate taps being disposed in the safety circuit, having a safety element, in particular a main contactor or a functional unit of the drive unit, said safety element being actuable by the safety circuit to the effect that, in the case of the interrupted safety circuit, a fault state of the safety element is activated in order to switch off the drive unit, in particular in order to disconnect the supply voltage from the drive unit, and that, in the case of the closed safety circuit, an active state of the safety element is activated in order to operate the drive unit for realizing the travel operation, in particular in order to connect the drive unit to the supply voltage, having monitoring devices for measuring and evaluating intermediate voltages and intervention devices being in an active connection with the safety circuit to the effect that the safety circuit is interruptible and/or at least one safety switch is capable of being bypassed by means of at least one disconnecting element (12, 31, 32, 33, 34, 35) which is switchable between a closed and an open switch position, the monitoring devices and the intervention devices being configured and realized to perform a test action in order to record at least one intermediate voltage as a function of a switch position of the at least one disconnecting element (12, 31, 32, 33, 34, 35), characterized in that the at least one disconnecting element (12, 31, 32, 33, 34, 35) is realized to the effect that the safety circuit is interruptible for less than 5 msec, preferably less than 2.5 msec, further preferably less than 1.3 msec, in order to detect the regular operating state of the elevator installation, in particular a maintenance bridge contacted in the safety circuit and/or a short circuit due to a fault, in the active state of the safety element, in particular the main contactor or the functional unit of the drive unit, by means of at least one test action. said control unit having an elevator car movable between floors along an elevator shaft and a drive unit for moving the elevator car between the floors, the control unit being realized for interacting with a safety circuit which is in particular laid through the elevator shaft and which is realized by a plurality of safety switches which are interconnected in series and which are switchable between an open state interrupting the travel operation and a closed state enabling the travel operation as a function of safety-related operating conditions of the elevator installation, the safety circuit, in particular at least one safety switch (4, 18), being capable of being bypassed sectionally by contacting a maintenance bridge, having intermediate taps (6, 21, 22, 23, 24, 25) for tapping an intermediate voltage, said intermediate taps being disposed in the safety circuit, having a safety element, in particular a main contactor or a functional unit of the drive unit, said safety element being actuable by the safety circuit to the effect that, in the case of the interrupted safety circuit, a fault state of the safety element is activated in order to switch off the drive unit, in particular in order to disconnect the supply voltage from the drive unit, and that, in the case of the closed safety circuit, an active state of the safety element is activated in order to operate the drive unit for realizing the travel operation, in particular in order to connect the drive unit to the supply voltage, having monitoring devices for measuring and evaluating intermediate voltages and intervention devices being in an active connection with the safety circuit to the effect that the safety circuit is interruptible and/or at least one safety switch is capable of being bypassed by means of at least one disconnecting element (12, 31, 32, 33, 34, 35) which is switchable between a closed and an open switch position, the monitoring devices and the intervention devices being configured and realized to perform a test action in order to record at least one intermediate voltage as a function of a switch position of the at least one disconnecting element (12, 31, 32, 33, 34, 35), characterized in that the at least one disconnecting element (12, 31, 32, 33, 34, 35) is realized to the effect that the safety circuit is interruptible for less than 5 msec, preferably less than 2.5 msec, further preferably less than 1.3 msec, in order to detect the regular operating state of the elevator installation, in particular a maintenance bridge contacted in the safety circuit and/or a short circuit due to a fault, in the active state of the safety element, in particular the main contactor or the functional unit of the drive unit, by means of at least one test action.