| 摘要 |
A circuit arrangement for load limiting and overload protection of a hoist drive having two lifting speeds which can be switched via a main lifting contactor and a fine lifting contactor. The circuit arrangement comprises a plurality of switches, a timer and contacts, which are controlled by the switches, in the current paths of the main lifting contactor and the fine lifting contactor. The switches can be operated as a function of the cable force and hence as a function of the load. One of the switches opens, as a partial load switch, during the transition from the cable being slack to being loaded, and the other limiting load switch opens when a maximum permissible limiting load is exceeded. The circuit is designed such that the partial load switch controls a partial load relay and the limiting load switch controls a limiting load relay, and the timer has a timer relay which is controlled by contacts of the partial load relay and of the limiting load relay and has a timer contact. The limiting load relay which is without any delay when the partial load switch is open, the limiting load switch is open and the timer contact is open and in a delayed manner when the timer contact is closed, as a result of which the main lifting contactor can be switched off by means of a normally-open contact and the fine lifting contactor by means of a further normally-open contact. The timer relay has a pull-in delay which is controlled by the said contacts of the partial load relay and of the limiting load relay and whose pull-in delay time does not elapse until the partial load switch is open and the limiting load switch is closed. ...
<??>Original abstract incomplete.
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