| 摘要 |
PURPOSE:To prevent mistrip of a plant due to malfunction or expansion of accidents due to erroneous non-operation at a trouble time by judging the operation to be abnormal when only one of a blocking relay and an operation confirming relay is operated. CONSTITUTION:If a blocking relay 2 is operated naturally though a trouble contact 1 is not closed, (a)-side contacts 2-a1-2-a3 are closed, and a (b)-side contact 2-b1 is closed. A (a)-side contact 3-a of an operation confirming relay 3 is opened still, and therefore, a plant stop command is not generated. Meanwhile, if the blocking relay 2 is not operated though the trouble contact 1 is closed because of the occurrence of a trouble, a voltage is impressed to the operation confirming relay 3 when the trouble contact 1 is closed, and then, the (a)-side contact 3-a is closed, and a (b)-side contact 3-b is opened. (a)-side contacts 2-a1-2-a3 of the blocking relay 2 are not closed, and the (b)-side contact 2-b1 is not opened, and therefore, the plant stop command is not generated, and trip of the plant is not caused. |
