| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive arc discharge detecting apparatus with the function of precluding error detection in a D.C. electrical system subject to periodic disturbances. SOLUTION: Arc discharge in the D.C. electrical system 1 is detected by a current sensor 13, and a detected-current signal is filtered by a band-pass filter 17. A filtered-current signal 21 is integrated by a resettable integrator 27 every repetitive period. A microprocessor 25 samples an integrated/filtered- current signal 29 at a frequency lower than the frequency of a pass band, resets the integrator 27, computes a sample accumulated value attenuated with the passage of time, and generates an arc damage signal when the sample accumulated value 2 attenuated with the passage of time reaches a threshold value. The detected-current signal 15 is compared with a mean current signal 35 by a comparator 37 for precluding error detection. After the detected current signal exceeds the means current signal, only samples acquired during a set time are accumulated. An overload protection means is provided through the use of the mean current signal 35.
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