Title:
LEAK DETECTOR
Document Type and Number:
Japanese Patent JP2017188986
Kind Code:
A
Abstract:
PROBLEM TO BE SOLVED: To suppress the false detection attributed to harmonics noise, surge or an abnormal waveform, and to enable the highly accurate detection for leak waveforms including a waveform subjected to rectification by a load.SOLUTION: A leak detector comprises: a Σ modulator 4 for performing the A/D conversion of a difference signal of positive and negative output signals of a zero-phase-sequence current transformer 2; a digital filter 5 for removing a high frequency component from an output signal of the ΔΣ modulator 4; a digital comparator 6 for comparing an output signal of the digital filter 5 with a positive-side threshold and a negative-side threshold to output detection signals 6a, 6b, 6c; a trip control signal generator 7 for outputting trip control signals 7a, 7b based on the detection signals 6a, 6b, 6c output by the digital comparator 6; a leak-determination device 8 for determining a leak state on an AC line based on the trip control signals 7a, 7b; a delay counter 9 which outputs a final trip control signal 9a if the leak-determination device 8 has output a leak determination signal 8a over a first given time; and a switch drive circuit 10 which cuts the AC line 1 by an earth leakage circuit breaker 15 when the delay counter 9 outputs the final trip control signal 9a.SELECTED DRAWING: Figure 1
Inventors:
ONISHI YU
Application Number:
JP2016074850A
Publication Date:
October 12, 2017
Filing Date:
April 04, 2016
Export Citation:
Assignee:
NEW JAPAN RADIO CO LTD
International Classes:
H02H3/16; H01H83/02; H02H3/027
Attorney, Agent or Firm:
Tsuneaki Nagao