In order to provide a method for regulating a reactive power compensator, which is connected to an alternating current line having multiple phases, wherein for each phase an actual voltage V12, V23 and V31 present thereon is detected and from the actual voltages V12, V23 and V31 a counter system actual fraction is calculated. The door cable pulley system includes a first tension pulley, a second tension pulley, a cable drum driven by a motor, and a pair of drive cables. The coactive members may be in the form of chains, rods, cables, wires, granular inert materials such as gravel or metal balls or other impact means. In one example, the service device is a crane.