JPH09288058A - Gas-in-oil detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-in-oil detector capable of easily installing, removing and manufacturing and inhibiting invasion of insulation oil into an optical transmission line. SOLUTION: The gas-in-oil detector separates gas dissolved in oil, and optically detects the collected gas by using an optical fiber. In this case, the detector comprises a gas-in-oil separator 21 for separately extracting the gas dissolved in oil, an optical detecting unit 22 for detecting the separately extracted oil to be formed divisionally from the separator 21, and a conduit 23 for coupling the separator 21 to the unit 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-oil gas detector for separating a gas dissolved in oil and optically detecting the collected gas using an optical fiber.

[0002]

2. Description of the Related Art In recent years, the importance of equipment diagnosis has been increasing due to the demand for high reliability of electric power equipment. As a method for diagnosing oil-filled electric devices such as transformers and OF cables, a method of performing deterioration phenomena such as internal partial discharge and local heating by gas analysis in oil is widely used.

This analysis procedure takes a method in which after temporarily stopping the operation of the electric equipment, oil is extracted from the electric equipment, gas is separated from the oil, and the gas is measured by a dedicated gas analyzer. . However, this method requires a lot of cost and labor because the measurement procedure is complicated, most of it is manual work, and a power failure is required.

Therefore, in recent years, a method of mounting a sensor for detecting dissolved gas in oil in the oiling hole of the cable connecting portion and constantly monitoring the detection information of the sensor is being studied.

For example, as shown in FIG. 5, there is a device that utilizes the optical properties of gas and remotely measures the dissolved gas concentration in oil by using an optical fiber.

Here, the structure will be described. The gas-in-oil separation cell 3 is attached to the connecting portion 2 of the OF cable 1 or the like. The oil-in-gas separation cell 3 includes an oil phase chamber 4 filled with insulating oil extracted from the OF cable 1 and a gas phase chamber 5 through which various gases (hydrocarbon-based gas etc.) in the insulating oil permeate. And have. The oil phase chamber 4 is provided so as to surround the gas phase chamber 5, and these are partitioned by a permeable membrane 6 obtained by coating a porous metal with a fluororesin (PFA or the like). Then, the connection portion 2 between the OF cable 1 and the oil phase chamber 4 is connected via a conduit. This connection 2
Insulating oil is extracted and filled in the oil phase chamber 4, various gases dissolved in this insulating oil are permeated by the permeable membrane 6, and are separated and captured in the gas phase chamber 5.

Optical fibers 7 and 8 serving as optical transmission means are provided at both ends of the gas phase chamber 5 in the gas-in-oil separation cell 3, respectively, and end portions 9 of these optical fibers 7 and 8 are provided. , 10 are arranged in the gas phase chamber 5 at a predetermined interval. Between the respective ends 9 and 10 of the optical fibers 7 and 8, an optical transmission line 11 is formed which transmits through the atmosphere in which various gases trapped in the gas phase chamber 5 are mixed.

A monitoring box 12 for analyzing the gas is provided at a position distant from the connecting portion 2 to which the gas-in-oil separation cell 3 is attached, for example, a monitoring station. In this surveillance box 12,
A light emitting means for generating and emitting light having different wavelengths matching the absorption spectra of various gases is provided for each gas, and the signal processing unit 1 for detecting the returned light to obtain the gas concentration.
8 is further provided, and a deterioration diagnosis unit 20 for diagnosing deterioration of the OF cable 1 and the like is further provided.

The light emitting means is provided with, for example, a laser device 13 for producing a laser beam having a wavelength equal to the infrared absorption spectrum of acetylene, and a drive circuit 14 for driving the laser device 13.

The signal processing unit 18 has a photodetector 19 connected to the optical fiber 8, and a gas signal obtained by phase sensitive detection of a specific component in the detection signal obtained by the photodetector 19. Therefore, the gas concentration is obtained.
The deterioration diagnosis unit 20 is configured to perform deterioration diagnosis of the OF cable 1 and the like based on the gas concentration information obtained by the signal processing unit 18.

The laser device 13 is connected to one end of a gas phase chamber 5 for trapping the gas in the oil-in-oil gas separation cell 3 through an optical fiber 7 which is a light transmission means for the outward path. The other end of the vapor phase chamber 5 is connected to the photodetector 19 via the optical fiber 8 for the return path.

With the above structure, the laser light from the laser device 13 in the monitoring box 12 passes through the optical fiber 7 for the forward path, the optical transmission path 11 and the optical fiber 8 for the return path, enters the signal processing section 18, and deteriorates. The diagnosis unit 20 performs deterioration diagnosis of the OF cable 1 and the like.

[0013]

However, in the above-mentioned conventional technique, the mechanism for separating the gas in oil and the mechanism for detecting the gas (optical transmission line) are provided in the gas-in-oil separation cell. Therefore, there are the following problems.

(1) The gas-in-oil separation cell is large, and
Usually, the OF cable connecting portions are closely arranged in the upper and lower sides of the three phases, so that they are difficult to install and remove.

(2) If the permeable membrane is damaged,
Insulating oil penetrates into the optical transmission line, and the optical transmission line and the optical fiber are damaged.

(3) Since it is necessary to simultaneously seal the oil phase chamber and the gas phase chamber, and the mechanism for separating the gas in oil and the mechanism for detecting the gas are combined, the fabrication is extremely difficult. Difficult to do.

Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide a gas-in-oil detector which is easy to install, remove and manufacture and which does not allow insulating oil to enter the optical transmission line. .

[0018]

In order to solve the above-mentioned problems, the present invention relates to a gas-in-oil detector for separating a gas dissolved in oil and optically detecting the collected gas using an optical fiber. The in-oil gas separation section for separating and extracting the gas dissolved in oil, and the optical detection section for detecting the separated and extracted gas are formed separately, and the gas-in-oil separation section and the optical detection section are formed. A conduit for connection is provided.

The conduit is preferably equipped with a valve in the middle thereof.

According to the above construction, the gas-in-oil separation cell installed in the connecting portion can be downsized, and the installation, removal and manufacture are facilitated, and the gas-in-oil separation section and the optical detection section are separated. Moreover, since the valve is provided in the middle, insulating oil does not enter the optical transmission line.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a device for detecting gas in oil according to the present invention.

First, the structure of the present invention will be described. The present invention is characterized in that an in-oil gas separation unit that separates and extracts a gas dissolved in oil and an optical detection unit that detects the separated and extracted gas are formed separately. .

As shown in the figure, the connecting portion 2 of the OF cable 1 is provided with an in-oil gas separating portion 21 for separating and extracting gas dissolved in oil. This in-oil gas separation unit 21
Has an oil phase chamber 4 filled with insulating oil extracted from the OF cable 1 and a gas phase chamber 5 through which various gases (hydrocarbon-based gas etc.) in the insulating oil permeate. Oil phase chamber 4
The gas phase chamber 5 is made of a porous metal made of fluororesin (PFA, etc.).
It is partitioned by the permeable membrane 6 coated with.
The gas phase chamber 5 is formed by a permeable membrane 6 formed in a cylindrical shape, and the oil phase chamber 4 is provided so as to surround the gas phase chamber 5. The inside is a permeable membrane 6, and the outside is a cylindrical outer cylinder 4a. Is formed by. The lid plates 4b and 4c are hermetically fixed to both ends of the oil phase chamber 4 and the gas phase chamber 5, respectively.

The OF cable 1 and the oil phase chamber 4 are connected from the connecting portion 2 of the OF cable 1 via a conduit. Insulating oil is extracted from this connection portion 2 into the oil phase chamber 4 and filled,
Various gases dissolved in the insulating oil are permeated by the permeable membrane 6 and are separated and captured in the gas phase chamber 5.

The gas phase chamber 5 is formed separately from the in-oil gas separating section 21 via a conduit 23 and a valve 24, and is connected to an optical detecting section 22 for detecting gas.
The various gases that have been separated and captured in (4) are introduced into the optical detection section 22 through the conduit 23 and the valve 24. The optical detection section 22 is provided with optical fibers 7 and 8 as optical transmission means facing the optical detection section 22 at both ends thereof. The respective end portions 9 and 10 of the optical fibers 7 and 8 are coaxially arranged in the optical detection portion 22 with a predetermined interval, and the optical transmission path 27 that transmits the mixed atmosphere in the optical detection portion 22 is provided. Is forming.

A monitoring box 12 for analyzing the gas is provided at a position distant from the connecting portion 2 to which the in-oil gas separating portion 21 is attached, for example, a monitoring place. In this surveillance box 12,
A light emitting means for generating and emitting light having different wavelengths matching the absorption spectra of various gases is provided for each gas, and the signal processing unit 1 for detecting the returned light to obtain the gas concentration.
8 is further provided, and a deterioration diagnosis unit 20 for diagnosing deterioration of the OF cable 1 and the like is further provided.

The light emitting means is provided with, for example, a laser device 13 for generating a laser beam having a wavelength equal to the infrared absorption spectrum of acetylene, and a drive circuit 14 for driving the laser device 13 (another laser device). Is not shown).

The signal processing unit 18 has a photodetector 19 connected to the optical fiber 8, and a gas signal obtained by phase sensitive detection of a specific component in the detection signal obtained by the photodetector 19. Therefore, the gas concentration is obtained.
The deterioration diagnosis unit 20 is configured to perform deterioration diagnosis of the OF cable 1 and the like based on the gas concentration information obtained by the signal processing unit 18. In addition, the signal processing unit 18 includes the drive circuit 1
4 is connected and driven by this.

The laser device 13 is connected to one end of the optical detection section 22 via the optical fiber 7 which is the optical transmission means for the forward path. The other end of the optical detector 22 is connected to the photodetector 19 via the optical fiber 8 for the return path.

The valve 24 provided in the middle of the conduit 23 that connects the gas-in-oil separating section 21 and the optical detecting section 22 is shown in FIG.
As shown in FIG. 3, the inner diameter is formed larger than the inner diameter of the conduit 23, and the tapered portions 26 connecting the inside of the conduit 23 and the inside of the valve 24 are formed at both ends thereof. A sphere 25 having a diameter larger than the inner diameter of the conduit 23 and smaller than the inner diameter of the valve 24 is inserted and provided in the valve 24. That is, even if the normal gas passes through the conduit 23 under atmospheric pressure and enters the valve 24, the sphere 25
Does not move from the illustrated state, and various gases can pass through the gap. However, if the gas separation unit 21
When the permeable membrane of the device is damaged and the insulating oil flows into the valve 24, the spherical body 25 is pressed by the hydraulic pressure and is pressed against the taper portion 26 on the optical detection unit 22 side to be fixed, and It is configured so that oil does not enter the optical detection unit 22 side.

In this embodiment, the connecting portion 2
Although the in-oil gas separating section 21 is attached to the upper port of the oil, as shown in JP-A-4-9735, the circulation of oil is performed from the upper port of the connecting section to the gas separating section in the oil and the lower opening of the connecting section. By forming the system passage, the gas in oil can be detected quickly.

The operation of the embodiment of the present invention having the above configuration will be described based on the method of use.

When the OF cable 1 is deteriorated, the insulating oil is decomposed by local heating or partial discharge, and a hydrocarbon-based gas or the like is generated and dissolved in the oil.

First, the in-oil gas separating portion 21 is connected from the upper port of the connecting portion 2 via a conduit. And OF cable 1
The insulating oil therein is extracted and filled in the oil phase chamber 4. Various gases (hydrocarbon gas, etc.) in the insulating oil filling the oil phase chamber 4 are
The gas passes through the permeable membrane 6 that allows only gas to enter the gas phase chamber 5. The various gases that have permeated into the gas phase chamber 5 move into the optical detection unit 22 via the conduit 23 and the valve 24. After a lapse of a predetermined time, the gas phase chamber 5 and the optical transmission path 27 in the optical detection section 22 are filled with gas.

On the other hand, in the monitoring box 12, as an example,
A laser device 13 that generates laser light having a wavelength equal to the infrared absorption spectrum of acetylene is driven by a drive circuit 14 to emit laser light. The emitted laser light enters the optical fiber 7 for the outward path, is transmitted into the optical detection section 22 having a gas detection function, passes from the end portion 9 of the optical fiber 7 through the optical transmission path 27, and is used for the return path. The light enters the end portion 10 of the optical fiber 8, is transmitted through the optical fiber 8, and enters the photodetector 19.

Then, in the detection signal obtained by the photodetector 19, the gas concentration is obtained by the signal processing section 18 from the gas signal obtained by phase sensitive detection of a specific component. This gas concentration information is sent to the deterioration diagnosis unit 20, where the deterioration diagnosis of the OF cable 1 is performed.

As described above, since the in-oil gas separation section 21 and the optical detection section 22 are formed separately, the size of the in-oil gas separation cell 3 up to now is φ150 mm × L350.
The size was reduced from mm to φ100 mm × L100 mm.

The conduit 23 connecting the gas-in-oil separating section 21 and the optical detecting section 22 was experimentally determined to have an inner diameter of about φ4 and a length of 5
It was required that a length of 00 mm or less be appropriate. less than,
The experimental results are shown.

A comparative experiment of gas permeation between the gas cell with a built-in optical system (the optical system is present in the gas separation part Vg) and the split type gas cell (the gas separation part Vg and the optical system Vk are split + the conduit Vh) was conducted. FIG. 3 shows the experimental configuration, FIG. 4 shows the results of the gas permeation experiment in oil, and Table 1 shows the volume conditions.

[0041]

[Table 1]

The gas concentration measured by the separation-type gas cell was considered to deviate from the theoretical curve because the component of the diffusion resistance of the conduit was added, but in the case of inner diameter φ4 × conduit length 500 mm,
Since the measured length and the theoretical curve match, it was found that only the increase in the gas phase side volume should be considered when considering the overall time constant.

It has been confirmed in other experiments that the time constant is doubled when the conduit length is 1000 mm, and the time constant is quadrupled when the conduit diameter is φ2. Considering these results, and since the volume increases as the diameter increases and the time constant increases accordingly, it is clear that a diameter of about φ4 and a conduit length of 500 mm or less are appropriate. Further, the conduit length of 500 mm is an appropriate value because it is a distance having a space for installing the optical detection portion, considering an OF cable real line in which three phases are lined up.

Table 2 summarizes the time constants (63% transmission) and saturation times (90%) of this experiment from the following theoretical formulas.

Τ (63%) = V / (101325 × A × α) τ (90%) = 2.3 × V / (101325 × A × α) τ: Gas permeation time constant in oil V: Gas phase side Volume A: membrane area (65.97 × 10 ⁻⁴ m ² ) α: gas permeation coefficient in oil (1 / m ² · s · Pa) CH ₄ = 8.14 × 10 ⁻¹¹ , C ₂ H ₂ = 9 .47 x 1
0 ^-11

[0046]

[Table 2]

The actual volume on the gas phase side of the photodetector is 40 cc.
Considering the degree, it is considered from the above equation that the time constant is about 14 days (saturation about 1 month).

In the method of temporarily stopping the charged state of the OF cable, extracting the oil from the OF cable connecting portion, separating the gas from the oil, and measuring the gas concentration, it is a regular inspection every three years. It can be said that the above time constant is sufficient.

[0049]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) Since the gas-in-oil separation section and the optical detection section are formed separately, the gas-in-oil separation section can be downsized,
Easy installation and removal of the OF cable at the connection.

(2) Since the gas-in-oil separation section and the optical detection section can be individually manufactured, the manufacturing is easy.

(3) Individual repairs and replacements at the time of failure,
Excellent maintainability.

(4) Since the gas-in-oil separation section and the optical detection section are connected by a conduit and a valve is provided, the permeable membrane of the gas-in-oil separation section is damaged, and the insulating oil permeates into the gas phase section. Also stops at the valve and does not enter the optical transmission line of the photodetector.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a device for detecting gas in oil according to the present invention.

FIG. 2 is an enlarged sectional view of a valve.

FIG. 3 is an experimental configuration diagram of a comparative experiment of permeation of gas in oil.

FIG. 4 is a graph showing the results of a gas permeation experiment in oil.

FIG. 5 is a cross-sectional view showing a conventional gas-in-oil detector.

[Explanation of symbols]

 7, 8 Optical fiber 21 Gas separation part in oil 22 Optical detection part 23 Conduit 24 Valve

Claims (2)

[Claims] 1. A method for separating gas dissolved in oil,
In an oil-in-gas detection device that optically detects a collected gas using an optical fiber, an in-oil gas separation unit that separates and extracts a gas dissolved in oil, and an optical detection unit that detects the separated and extracted gas A gas-in-oil detection device, characterized in that a conduit connecting the above-mentioned gas-in-oil separation section and the above-mentioned optical detection section is provided. 2. The in-oil gas detection device according to claim 1, wherein the conduit is provided with a valve in the middle thereof.