| 摘要 |
Device for generating a current (I) corresponding to the input quantity (A) of the device, for example for a digitally working process control system, comprises two parallel-working current-generating members (1, 2), each one connected to a current summation member (3). The current-generating members are each one adapted to generate a current (I1, I2) proportional to the quantity (A), the proportionality being determined by an influenceable proportionality factor (k1, k2). Further, each one of the current-generating members is adapted to supervise both its own function and that of the other member. Upon indication of a malfunction in one of the current-generating members, the function of the device is taken over by the other member alone. Each one of the current-generating members may preferably by adapted, by means of switching members (6, 7), to establish an alternative path for the generated current. The device is further adapted to sense whether an indicated malfunction in one of the current-generating members is caused by an internal fault in the current-generating member or by an external fault such as an interruption in the part of the circuit, which is connected to the current measuring member. <IMAGE> |
