Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Polyphase
Patent
1987-05-26
1990-01-16
Karlsen, Ernest F.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Polyphase
324 96, 324142, G01R 1900, G01R 3100, G01R 2100
Patent
active
048946095
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD TO WHICH THE INVENTION RELATES
This invention relates to a porcelain insulator having at least one optical transmission medium embedded therein, which insulator is suitable for supporting a power line conductor while allowing optical connection to an optical sensor for the measurement of the current and voltage of the power line conductor.
This invention also relates to an insulator suitable for the use of converting electric signals on a power line into optical signals to be transmitted to a measuring unit, which insulator can be connected to a light-emitter means and a light-detector means through optical fiber cables.
Further, the invention relates to an electric measuring device with optical sensors for detection and measurement of the zero-phase-sequence current or zero-phase-sequence voltage of a three-phase power line as well as the currents and voltages of individual phases thereof.
BACKGROUND ART
The demand for electric power has been diversified these years, and the need for reliable power supply and quick response to any changes is ever increasing. To meet this need, information on the conditions of power supply, such as line voltages and line currents, must be collected at a high speed through accurate measurement over a wide service area at as many locations as possible. The inventors noted that optical sensors, such as electro-optic elements, are suitable not only for accurate measurement but also for communication of a large amount of data at a high speed through the optical fiber communication systems.
Support insulators of electric apparatus which allow the use of optical are known, for example, Japanese Patent Laid-open Publication No. 143,619/1982 discloses an insulator having communication optical fiber disposed therein.
FIG. 16 shows an example of an insulator with an optical fiber as shown in to the prior art. An insulator body 81 has a hole 81a extending therethrough, and an optical fiber 84 with optical connectors 82, 83 mounted at opposite ends thereof is disposed in the hole 81a. For protection against moisture and dust particles, the hole 81a is sealed, for instance, by an O-ring 85 and filler 86.
The above referred insulator has a shortcoming in that the sealed portion, such as the O-ring 85 and the filler 86, is susceptible to deterioration due to external forces, temperature variations, moisture and aging. It has been difficult to keep the sealed portion intact over a long period of time in a stable manner. Thus, optical sensors connected to the optical fibers 84 in the insulator body 81 have experienced troubles due to insulation deterioration in the hole 81a or deterioration of the optical fiber 84 itself caused by moisture absorption or water infiltration. Further, the operation of inserting the optical fiber 84 in the hole 81 is cumbersome, and it has been a stumbling block for the quality control and mass production of the insulator.
Therefore, an object of the present invention is to provide a porcelain insulator with one or more optical transmission media, e.g., optical fibers, embedded therein, which insulator maintains excellent insulation and optical transmission over a long service life in a stable fashion, while eliminating the above-mentioned shortcomings of the prior art under certain external conditions and aging.
FIG. 17 shows a circuit diagram of a conventional device for detecting and measuring the zero-phase-sequence current of a three-phase power line, and FIG. 18 shows a similar circuit diagram of the prior art for detecting and measuring the zero-phase-sequence voltage of the three-phase power line.
For zero-phase-sequence current measurement, secondary windings of three current transformers 92 mounted on the three power line conductors 91 are connected in series by lead wires 93 and the serial circuit is closed by a resistor 94 as shown in FIG. 17. Voltage across the output terminals 95, 95 represents the sum of the zero-phase-sequence currents in the three phase line conductors 91.
Under normal conditions, the currents in the three-p
REFERENCES:
patent: 3312898 (1967-04-01), Browne et al.
patent: 3324393 (1967-06-01), Casey et al.
patent: 3506833 (1970-04-01), Von Willisen
patent: 3662263 (1972-05-01), Besel
patent: 3679974 (1972-07-01), Mollenbeck
patent: 4269483 (1981-05-01), Feldtkeller
Fujiki Toshisada
Furukawa Yoshinari
Kato Kazuaki
Kondo Taikichi
Okimoto Akimichi
Karlsen Ernest F.
NGK Insulators Ltd.
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