| 摘要 |
PURPOSE:To make visible present situations and abnormality analyses by memorizing desired protective characteristic curves, input and output signal data, set data, and input signal data at the time when abnormal situation occurs and displaying them analogously or digital means. CONSTITUTION:A liquid crystal display 10, a mode selection switch 6, and ten-key 7 are installed as analogue data display means in the surface of a digital over current relay(DOCR) 5. The electric current to run in an apparatus to be protected is led to the DOCR 5 through a transformer and converted into a digital number. Meanwhile, a plurality of operation characteristic curves of the current and an operation time are set in a memory and a curve which is suitable for the apparatus to be protected is displayed on the display 10 by the switch 6 and keys 7 and a protective signal is put out when the put current is agreed with the curve. Further, the value of the input electric signal or the passing time at the time when value surpasses the rated value are memorized and displayed if necessary. |
