Safety device for monitoring a movable element

Abstract

A safety device for monitoring a movable element, in particular, for elevators, is provided. The safety device includes a speed determination unit for determining the speed of the movable element, a comparator device for comparing a predetermined speed with the determined, actual value, a triggering unit for triggering a braking device, and a distance determination unit for determining the distance of the movable element in relation to a stationary or movable target. The comparator device comprises a memory for storing a maximum admissible speed and at least one nominal distance with an associated nominal speed. The comparator device compares a greatest stored nominal distance with an actual distance indicated by the distance determination unit. When the nominal distance is the same as the actual distance, the comparator device compares the nominal speed associated with the nominal distance with the actual speed registered by the speed determination unit at this point of time. When the nominal speed is exceeded the comparator device causes the triggering unit to emit an electronic triggering signal. The comparator device continuously compares the maximum admissible speed with the actual speed irrespective of nominal distances and when the maximum admissible speed is exceeded causes the triggering unit to emit the electronic triggering signal.