| 摘要 |
<p>The control circuit comprises a circuit consisting of a controlled plant (5) a meter (10) for the process variable, a controller (16) and a final control element (20). A signal transmitter (26) for the auxiliary process variable is provided near the input to the controlled plant (5). The output of transmitter (26) is connected to one input of a selector (30), the other input of which is connected to a function transmitter (32) in turn connected to the output of controller (16). The output of selector (30) acts on controller (16). A disturbance indicator (34) is also connected to the signal transmitter (26), and acts on the selector in such a manner that as soon as the output signal of the signal transmitter (26) falls below a bottom threshold or exceeds a top threshold at the disturbance indicator (34) the controller (16) is influenced by the function transmitter (32) instead of by the signal transmitter (26). (Fig. 1)</p> |
