One question per day (1130)

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This post was last edited by Wang Tianze on 2015-12-1 21:11. One question per day; since it involves electrical engineering knowledge, it was initially published on the dashboard version, and starting from 12.01, it will be published on the electrical engineering version. 54. The basis for determining the forward and reverse actions of a regulator in a control system is ( ). A. Achieve positive feedback in the closed-loop circuit B. Ensure an appropriate amplification factor for the system C. Guarantee production safety D. Achieve negative feedback in the closed-loop circuit. 55. What should be done when stopping a differential pressure transmitter? A. Open the balance valve first, then open the positive and negative valves. B. Open the balance valve first, then close the positive and negative valves. C. Close the balance valve first, then open the positive and negative valves. D. Close the balance valve first, then close the positive and negative valves. Regarding question 55: It concerns the sequence in which the valves are opened when stopping the meter, that is, regarding the operation and shutdown of the instrument. When stopping: the sequence should be turn off negative pressure, turn on balance, and turn off positive pressure. The operation of the three-valve assembly follows two principles: 1. It is not allowed for the condensate in the conduits or the isolation fluid in the isolation tanks to be lost ； 2. It must not be subjected to unidirectional compression or heating. Everyone might want to consider these steps for putting it into operation. After this post was published, several members pointed out that the answer to question 55 was incorrect, which is great! What we want is discussion; we’re not confined to the given results!