| 摘要 |
A device for closing a passageway, which device comprises a closing body that can be moved by means of a motor along a guiding from a closed position to an open position and vice versa, wherein the body is provided with a safety sensor interrupting the motor feed, is incorporated in a circuit with separate feed connected fixedly to the movable body and the circuit is provided with a conductor which extends in the direction of movement and which is guided slidably along at least one fixed coil disposed close to the guiding, which coil is a part of the control circuit for the motor, wherein the safety sensor comprises one or more break contacts connected in series, and further connected in series with a capacitor in the circuit so being able to measure the frequency change in the circuit, instead of operating on the usual measuring of a resistance or power change when the sensor is activated. <IMAGE> |
