| 摘要 |
PURPOSE:To make a blocking output effective immediately after a failure occurs and obtain a high speed operation by a method wherein the blocking output is made to be effective when failure detection signals are generated and the blocking output is memorized for a certain period. CONSTITUTION:When the value of a suppression function obtained by a suppression function calculating means 1 is larger than a predetermined relation with a differential function obtained by a differential function calculating means 2, a blocking output generating means 5 generates a blocking output Pl. The blocking output generating means 5 makes the blocking output Pl effective in accordance with the control of failure detection signals Sf1 and Sf2. Further, the blocking output generating means 5 memorizes the blocking output Pl obtained by data while the signals Sf1 and Sf2 are generated for a predetermined period. With this constitution, in the case of an external failure, even if a current transformer is saturated, a malfunction caused by the blocking output Pl can be avoided. Further, in the case of an internal failure, as the blocking output Pl is not generated, a high speed operation can be obtained. |
