Title:
EARTH DETECTING DEVICE
Document Type and Number:
Japanese Patent JP3266003
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To safely detect a zero-phase voltage in non-contact by measuring the field intensity of three-phase AC distribution lines, obtaining the potential difference, comparing the potential difference in this cycle with the potential difference preceding it by one or more cycles, and detecting the zero-phase voltage from its output.
SOLUTION: A measuring unit section 6 is formed so that electrodes 1, 2 measuring the field intensity formed around one phase of three-phase AC distribution lines 3 have set positional relations. The potential difference between the electrodes 1, 2 is inputted to a photoelectric potential sensor 5, it is converted into the light-modulated signal proportioned to the potential difference, and the signal is sent to an input/output conversion section 8 via an optical fiber cable 13. The light-modulated signal is converted into the potential difference signal proportional to it, a change quantity detection section 9 calculates the difference between this signal and the potential difference signal preceding it by one or more cycles during the healthy period, and a correction arithmetic section 11 detemines the correction arithmetic value based on the assembling state of the three-phase AC distribution lines 3 from an input section 10 and the correction parameters corresponding to the arranged positions of the electrodes 1, 2. A zero-phase voltage detection section 12 detects the zero-phase voltage based on the difference arithmetic value and the correction arithmetic value.
Inventors:
Koji Kasai
Application Number:
JP23633096A
Publication Date:
March 18, 2002
Filing Date:
September 06, 1996
Export Citation:
Assignee:
Matsushita Electric Industrial Co., Ltd
International Classes:
G01R31/02; G01R29/16; H01F38/24; H02H3/34; (IPC1-7): G01R29/16; G01R31/02
Domestic Patent References:
| JP296668A | ||||
| JP3105261A | ||||
| JP650995A | ||||
| JP59165912A | ||||
| JP220173U |
Attorney, Agent or Firm:
Fumio Iwahashi (2 others)