JPS6363923A - Oil-filled bushing - Google Patents

Abstract

PURPOSE:To achieve a high reliability, by mounting inside an oil-filed bushing a detector built by fastening a refractive index distribution type rod lens at both ends of a pipe having an opening on the side thereof. CONSTITUTION:Normally, as an oil surface of an insulating oil 7 is positioned in an expansion cylinder 3, a detector 10 is immersed into the insulating oil 7. Light reaches the detector 10 through an optical fiber 13 for transmitting light and is made incident on a rod lens 15. As the oil surface falls below the detector 10 in case of a oil leakage, light transmitted from the rod lens 15 reaches the rod lens 16 because a space in a pipe 18 is filled with a gas. The light incident on the rod lens 16 is focused at a spot with an action opposite to that on the light transmitting side to be incident on an optical fiber 14 for receiving light. The light is transmitted to a light receiver 12 through the light receiving optical fiber 14 to be used as abnormality detection signal. That is, normally, light is not detected with the light receiver 12 while light is detected in case of abnormality. Thus, constant monitoring is possible from a remote point by placing a light transmitter 11 and the light receiver 12 at an operation chamber or the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an oil-filled bushing used as an outlet of electrical equipment, and particularly to an oil-filled bushing that uses light to monitor a drop in oil level due to oil leakage. This invention relates to an oil-filled bushing equipped with an oil level monitoring device suitable for.

[Conventional technology]

Conventionally, the oil level of oil-filled bushings has been monitored by installing a glass window on the expansion cylinder attached to the insulator tube head of the oil-filled bushing and visually checking the oil level in the glass window of the piece and the movement of the pointer. It was

This type of oil level monitoring requires an inspection worker to come to the location where the electrical equipment is installed and check it, which requires a lot of manpower and is difficult to monitor at all times. Furthermore, depending on the position of the oil-filled bushing, it may be difficult to visually inspect it.

On the other hand, since the upper part of the bushing is at high voltage, it is difficult to directly extract the movement of the oil level to the outside as an electrical signal due to insulation reasons. Therefore, as described in Japanese Patent Application Laid-open No. 60-27817, a system has been proposed in which an optical fiber is used and a light shielding plate attached to a float blocks the optical path of the optical fiber when the oil level is low. Also, JP-A-60-278
Publication No. 18 discloses that the cladding layer of an optical fiber is peeled off to expose the core, and the part is immersed in oil in an expansion tube, and when the exposed core part comes into contact with the gas space when the oil level drops, loss of the optical fiber occurs. A method of changing the amount of light received has also been proposed.

[Problem that the invention seeks to solve]

Since these methods use optical fibers, there are no problems with insulation, and the oil level drop can be constantly monitored with a simple configuration. There was a problem of lack of reliability as no consideration was taken.

SUMMARY OF THE INVENTION An object of the present invention is to provide an oil-filled bushing that has a simple configuration and is equipped with a highly reliable oil level monitoring device.

[Means for solving problems] The above purpose is to install a detector consisting of a gradient index rod lens fixed to both ends of a pipe with an opening on the side inside an oil-filled bushing, and to detect the problem. This is achieved by connecting the fluorescent lamp and the fluorescent device with an optical fiber.

[Effect]

With the above configuration, the pipe-equipped detector with the opening is installed at the lower limit level of the oil level. Under normal conditions, the opening of the pipe contains oil, and the light sent from the light transmission fiber through the transmission-side gradient index rod lens is scattered by the oil and greatly attenuated while being transmitted through the pipe. Therefore, the amount of light received through the gradient index rod lens on the light receiving side is small.

On the other hand, if the oil level drops due to an oil leak or the like, the opening of the pipe becomes a gas space and the amount of transmitted light is received with almost no attenuation, so the amount of received light increases and abnormalities such as a drop in the oil level can be detected.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.

In FIG. 1, an oil-filled bushing 1 includes an expansion tube 3. A ground portion 4 fixed to the lower part of the upper plate Iv12. It is composed of a lower insulator tube 5 fixed to the lower part of the earth part 4 and a center conductor 6 penetrating through the oil-filled bushing 1. Insulating oil 7 is sealed inside the oil-filled bushing 1, and the oil level is within the expansion cylinder 2 under normal conditions.

A detector 10 is attached to the lower part of the expansion tube 2 . Detector 10 and light emitting device 1 provided outside the oil-filled bushing
1 and the light receiving device 1112 are connected through an oil-tight terminal 19 by a light transmitting optical fiber 13 and a light receiving optical fiber 14, respectively.

FIGS. 2 and 3 show a plan view and a front sectional view of the detector 10, respectively. The detector 10 is a transmission-side gradient index rod lens fixed to both ends of a pipe 18 having an opening 17 on the side. 13 and a gradient index rod lens 16 on the light receiving side. Light transmitting side gradient index rod lens 15
And on the end surface of the gradient index rod lens 16 on the light receiving side,
Optical fiber 13 for transmitting light and optical fiber 1 for receiving light, respectively.
4 are connected, and these optical components are enclosed in a case 21 via a cushioning material 22.

The effect will be explained. Under normal conditions, the curved surface of the insulating oil 7 is located within the expansion cylinder 3, so the detector 1o is immersed in the insulating oil 7. Therefore, the space in the pipe 18 between the light transmitting side gradient index rod lens 15 and the light receiving side gradient index rod lens 16 is filled with the insulating oil 7 entering from the opening 17.

On the other hand, to explain the propagation of light, the light sent from the light emitting device 11 passes through the light transmission optical fiber 13 to the detector 10.
, and enters the light transmitting side gradient index rod lens 15 as shown by the arrow. The refractive index gradient type Ronde lens can create parallel light as shown in the optical path 23 shown in Fig. 3 of the refractive index in the radial direction. The parallel light propagates through the space inside the pipe 18 along the optical path 23, but since the space inside the pipe 18 is filled with insulating oil 7, the light is scattered and almost never reaches the gradient index rod lens 16 on the receiving side. Therefore, no light is detected by the light receiving device 12.

When an oil leak occurs and the oil level falls below the detector 1o, pipe 1
8 is filled with gas, most of the light sent from the light transmitting side gradient index rod lens 15 reaches the light receiving side gradient index rod lens 16. The light incident on the gradient index rod lens 16 on the light receiving side is concentrated at one point by an effect opposite to that on the light transmitting side, and is made to enter the light receiving optical fiber 14.

The light is sent to the light receiving device 12 through the light receiving optical fiber 14 and used as an abnormality detection signal.

In other words, under normal conditions, the light receiving device i! 12, no light is detected, and light is detected when an abnormality occurs. By placing the light emitting device 11 and the light receiving device 12 in an operation room (not shown) or the like, constant monitoring is possible from a remote location.

According to this embodiment, the following effects are achieved.

(1) Optical fiber for light transmission 13. Light transmission side gradient index lens 15. Pipe 18. Since the light-receiving side gradient index lens 16 and the light-receiving optical fiber 14 are integrated and enclosed in the case 20, oil does not seep into the light-transmitting optical fiber 13 and the light-receiving optical fiber 14, allowing reliable monitoring. It becomes possible.

(2) Since there are no movable parts such as floats, there is no need to worry about malfunctions due to getting caught.

(3) Since the optical system is held by the buffer material 21, light fluctuations due to external forces are small.

FIG. 4 shows another embodiment of the invention. In this embodiment, the detector 10 is provided in the head space of the upper insulator tube 2. An abnormality is detected when the oil level of the insulating oil 7 drops below the position of the detector 10 in FIG. 4.

Note that the insulation performance of the oil-filled bushing 1 does not change even if the oil level drops to the head space of the upper insulator tube 2.

According to this embodiment, since the detector 10 is further attached to the upper insulator tube 2, it is possible to downsize the expansion tube 3, and the expansion tube can be assembled and removed using the light transmitting optical fiber 13 and the light receiving optical fiber 14. Assembling and disassembling work becomes easier because it can be done regardless of the situation.

FIGS. 5 and 6 are plan and front cross-sectional views, respectively, of a detector 10 showing other embodiments. In this example, the detector 1
The refractive index gradient lens 3o of 0 is a single object, and is constructed by providing an opening 17 therein.

According to this embodiment, since the refractive index gradient lens 30 constituting the detector 10 is composed of a single object, the detector becomes simpler and more reliable.

〔Effect of the invention〕

According to the present invention, an oil-filled bushing equipped with a highly reliable oil level monitoring device can be obtained with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an oil-filled bushing according to an embodiment of the present invention, FIG. 2 is a partial plan view of FIG. 1, FIG. 3 is a partial side view of FIG. 1, and FIG. 4 is a partial side view of FIG. A vertical cross-sectional view of an oil-filled bushing of another embodiment, and FIGS. 5 and 6 are cross-sectional views showing other embodiments of the detector.

Claims (1)

[Claims] 1. In an oil-filled bushing in which insulating oil is sealed, a detector configured by fixing graded index rod lenses to both ends of a pipe having an opening on the side surface is installed in the oil-filled bushing. An oil-filled bushing comprising an oil level monitoring device installed inside the bushing and connecting the detector and the fluorescent device with an optical fiber. 2. The oil-filled bushing according to claim 1, wherein the oil level monitoring device is provided within an expansion cylinder of the oil-filled bushing. 3. The oil-filled bushing according to claim 1, wherein the oil level monitoring device is provided in an internal space of the insulator tube head of the oil-filled bushing.