JPS6027818A - Oil level monitoring device for oil containing bushing - Google Patents

Abstract

PURPOSE:To ensure the monitoring of the lowering of oil level, by providing an optical fiber, whose core is partially exposed, in an expanding chamber, and utilizing the change in light transmittance. CONSTITUTION:In an expanding chamber 3, an optical fiber 91, whose core is partially exposed by stripping a part of a clad layer, is provided. The fiber 91 is taken out through an arm part 95 of an oil containing bushing. An light transmitter 97 is connected to one end of the fiber 91, and a light receiver 98 is connected to the other end. When an oil level is lowered, a material, i.e., an insulating oil 2, which is contacted with an exposed core 92 of the fiber 91 is transformed into a gas, e.g., nitrogen, on the oil surface. Therefore, light transmittance is changed, and the amount of light transmission at the exposed part 92 is changed. Since the amount of the received light of the light receiver 98 is changed, the lowering of the oil level can be always monitored positively by the change in the amount of the received light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil level monitoring device for an oil-filled bushing that has insulating oil sealed inside and has an expansion chamber in its upper portion, and particularly relates to a device that monitors a drop in oil level due to oil leakage or the like.

An example of a conventional oil-filled bushing equipped with this type of oil level monitoring device is shown in FIG. In Figure 1, (1)
is an oil-filled bushing, (2) is an insulating oil sealed in the oil-filled bushing, (3) is an upper expansion chamber, (4) is a center conductor,
(5) is the upper insulator, (6) is the capacitor cone, (7)
is the lower insulator, and (8) is the oil level gauge.

As the oil level gauge (8), as shown in the figure, a type that visually monitors the oil level through a glass window, or a dial type oil level gauge that has a float installed inside an expansion chamber and transmits its movement to a pointer is used.

However, in order to monitor the oil level with such conventional oil level gauges, an inspection worker must come to the location where the oil-filled bushing is used and visually check the oil level gauge. It is virtually impossible to monitor, and if the oil level gauge is difficult to see, such as when it is installed in a high place, it can be viewed using binoculars, making monitoring difficult and never satisfactory. . To solve these problems, it would be possible to install an alarm contact on the oil level gauge and pull it out to the outside, but since the upper part of the bushing is at high voltage, it is difficult to pull out the electrical contact to the outside due to insulation reasons. This invention utilizes an optical fiber, peels off a part of its cladding layer inside the lung chamber to expose the core, and guides the optical fiber to the outside from the ground part through the insulating tube of the oil-filled bushing. The change in the light transmittance in the exposed core part due to the change of the substance in contact with the exposed core part in accordance with the fluctuation is detected as a change in the amount of light received by the optical receiver provided at one end of the optical fiber, and the above-mentioned insulation The object of the present invention is to provide an oil level monitoring device that can constantly monitor the oil level without any problems.

The present invention will be explained below with reference to the embodiments shown in FIGS. 2 and 3. In Figures 2 and 3, (1
) to (8) are the same as those in FIG. (9) generally shows the oil level monitoring device according to the present invention.0 (91) is an optical fiber whose cladding layer is partially peeled off at a predetermined position in the expansion chamber (3) to expose the core (92). It is formed.

(93) is a mounting base for the optical fiber (91), and the optical fiber (91) is folded back inside the expansion chamber (3) and the upper insulator tube (
5) and the condenser cone (6) to reach the grounding part (94) of the oil-filled bushing (1), and from the grounding (94), the through connector (95) and the optical fiber Both ends of the cable (96) are led out to the outside. (97) is optical fiber (91)
A light emitting diode, for example, can be used as an optical transmitter that sends light into one end of the light emitting diode. (98) is an optical fiber (9
1) An optical receiver provided at the other end uses a photodiode, for example, and converts the received light into a corresponding electrical signal. (99) is a signal processing device connected to the optical receiver (98), which can be, for example, an alarm generating device or a voltmeter. In addition, the arrow (90A).

(90B) indicates the direction of light passing through the optical fiber (91).

FIG. 4 shows the structure of the optical fiber, with (911) the cladding layer, (912) the core, and (913) the transmitted light. It is known that when a part of the cladding layer (911) of an optical fiber is peeled off, the light transmittance changes depending on the refractive index of the material that comes into contact with the exposed core part, and this invention utilizes this principle. .

Next, the operation of the embodiment shown in FIGS. 2 and 3 will be explained. The core exposed portion (92) from which the cladding layer has been peeled off is provided at a predetermined position corresponding to the level of abnormal decrease in the curved surface (21) to be detected.

The exposed core portion (92) is completely immersed in the oil (2) when the oil level (21) is in the proper position. However, the oil level (
21) abnormally decreases due to some reason such as oil leakage, and when it decreases to the core exposed part (92), the substance that comes into contact with the core changes from the insulating oil (2) to a gas on the oil surface, such as nitrogen. ,
Because the refractive index of the insulating oil and the gas body are different, the exposed core part (9
In 2), the transmission of light changes. Therefore, the optical receiver (
The amount of light received by (98) also changes, and the signal processing device f! (99) can issue an alarm or visually display an alarm when the oil level is abnormally low.

In the above embodiment, it was described that the exposed core part (92) of the optical fiber is used as an alarm contact when the oil level is abnormally low. For example, as the oil level (21) decreases, the amount of the core exposed portion (92) coming out from the insulating oil (2) to the oil level (21) increases, and as a result, the amount of transmitted light changes continuously. By taking advantage of this change, the device of the present invention can also be used as an oil level gauge that monitors the oil level over a wide range of areas. In that case, if the influence of temperature on the amount of transmitted light becomes a problem, two optical fibers are installed along the same path, one with an exposed core and the other without an exposed core. By transmitting the same amount of light to these two optical fibers using an optical splitter, etc., and detecting the difference in the light-receiving layers from these optical fibers, errors due to temperature can be improved (6). .

As can be understood from the above, the upper limit position and lower limit position of the core exposed portion (92) may be set in accordance with a specific point such as the monitoring range of the curved surface level or an abnormal decrease.

As described above, according to the present invention, the optical fiber whose core is exposed by peeling off a part of the cladding layer in the expansion chamber of the oil-filled bushing is passed through the insulator tube of the oil-filled bushing, and both ends are led out from the ground part, Since an optical transmitter is provided at one end and an optical receiver is provided at the other end, it is possible to constantly monitor a drop in the oil level such as an abnormal drop in the curved surface of a bushing that is at a high potential without causing insulation problems.

Note that the transmission of light from the optical transmitter to the optical fiber may be performed continuously or intermittently at appropriate intervals.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional side view of an oil-filled bushing equipped with a conventional oil level gauge, FIG. 2 is a partial cross-sectional side view of an oil-filled bushing equipped with an oil level monitoring device according to the present invention, and FIG. FIG. 4 is a sectional view showing the main parts of the oil level monitoring device shown in the figure, and is a diagram for explaining the basic principle of the present invention, and the same reference numerals in the figures indicate the same or equivalent parts. In the figure, (1) is oil-filled bushing, (2) is insulating oil, (3) is expansion chamber, (5) is insulator pipe,
(91) is an optical fiber, (92) is a core exposed portion, (
94) is a grounding part, (97) is an optical transmitter, and (98) is an optical receiver. Agent Patent Attorney Masuo Oiwa Figure 1 Figure 3 Figure 4 Figure 1 Procedural amendment (spontaneous) 1. Indication of the case Japanese Patent Application No. 137107/1982 2. Name of the invention Oil level monitoring device for oil-filled bushings 3 , To the representative of the person making the amendment, Hitoshi Katayama, Department 4, Agent 5, "Detailed explanation of the invention" column 6 of the specification subject to amendment, Self-answer for amendment (1) Middle East page 2, line 7 of the specification "Upper insulator" has been corrected to "upper insulator tube." (2) Corrected "lower insulator" in line 8 of page 2 to "lower insulator". that's all

Claims (1)

[Claims] 1. In an oil level monitoring device for an oil-filled bushing that has insulating oil sealed inside and an expansion chamber at the top, an optical fiber whose core is exposed by peeling off a part of the cladding layer in the expansion chamber is inserted into the oil-filled bushing. Both ends of the oil-filled bushing are guided outside from the ground part of the oil-filled bushing through the inside of the insulator pipe, and the oil-filled bushing is equipped with an optical transmitter that sends light to one end of the optical fiber, and an optical receiver provided at the other end of the optical fiber. 2. A curved surface monitoring device for an oil-filled bushing according to claim 1, wherein a part of the cladding layer of the optical fiber is peeled off at a predetermined position corresponding to an abnormal drop in the oil level in the expansion chamber.