| 摘要 |
In order to monitor the two possible drive limit positions, two current direction-sensitive indicators (PPU1, PPU2) are provided which are connected in parallel with one another via exclusion contacts (WL/5, WL/6) of a running-direction selector. A direct voltage monitoring source (60V = ) conducts control potential to the two indicators via the rotary current lines (L1 to L4), the motor windings (W1 to W3) of the drive and its limit-position contacts (AK1 to AK4) if the drive (A) assumes one of its limit positions. In this process, a pole-turning changing switch (WL/1 to WL/4) which is connected into the adjustment and monitoring circuit and has the purpose of prescribing the respective running direction of the drive ensures that the phase position of the control potentials fed to the inputs of the two direct current indicators is the same in both drive limit positions. If the contacts of the running-direction selector switch at the wrong time, the phase position of the control potentials fed to the direct current indicators changes, the fault which has occurred being detectable from the switching state of the indicators. <IMAGE>
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