| 摘要 |
The invention relates to an emergency call device for the roof car of an external lift, in which a 4- pin or 5- pin socket installation, which originates from a mains connecting switch and is laid on the building roof, is provided for the 3-phase AC supply of the roof car, which car is connected via a line to one of the sockets and has the devices required for the operating movements, including the electrical switches, upstream of which a main contactor is connected. In order to avoid having to provide more conductors for such an emergency call device that are necessary for the power supply to the roof car, it is proposed that a capacitor (C1) be connected as a reactive current source upstream from the main contactor (KO) between the conductors (L1 and L2), via an opening contact of the main contactor (KO), and that, to detect the currents, a differential current measurement relay (F2) be connected into the conductors (L1 and L3) between the mains connecting switch (F0, F1, Q0) and the socket installation (SA) and a voltage measurement relay (F4) be placed between one of the conductors (L1-L3) and the neutral conductor (N), the relays (F2 and F3) closing the emergency call device circuit (ZLT) in the case of a current difference in the 3-phase network, which is loaded symmetrically during operation, and the relay (F4) closing the emergency call device circuit (ZLT) in the case of a voltage drop, while correspondingly linking the individual relay contacts. <IMAGE>
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