JPH0344546A - Detection of internal abnormality of gas insulated electric device - Google Patents

Abstract

PURPOSE:To detect the inner abnormality of a gas insulating transformer in a short time by detecting bad smell from such substance as aldehyde which generates bad smell through thermal cracking of SF6 gas and a solid insulating material by a sensor sensitive to said substance. CONSTITUTION:An SF6 gas 2 within a transformer tank 1 is circulated by a gas circulating pump 4 from a gas inlet passage 3 through a gas circulating pump 4, a valve 5a, a flange 6a, a sensor 7, a flange 6b, a valve 5b to a gas outlet passage 8. When an abnormality occurs within the tank 1, the SF6 or a solid insulating material are cracked to produce decomposing components. The decomposing components within the transformer 1 are mixed and detected in the sensor 7 along with the SF6 gas. The sensor 7 is a device obtained, for example, by sintering a metallic oxide such as SnO2, ZnO or the like on a platinum coil, so that the sensor 7 is quite sensitive to the substance generating bad smell like aldehyde, methylmercaptan, etc. Therefore, when the device is injected with electrons upon receipt of the bad smell, the density of free electrons is increased, thereby decreasing the resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for detecting the presence or absence of internal abnormalities, such as arc discharge or overheating, in gas-insulated electrical equipment such as SFs and gas-filled transformers.

[Conventional technology]

When an abnormality such as arc discharge or overheating occurs in a transformer, the SF, gas, and solid insulating material around the abnormality will become overheated.
Decomposition gas is generated. If this decomposition gas can be detected as early as possible, the spread of the accident can be prevented.

From the above point of view, SF is periodically collected from the transformer for the purpose of smooth operation of the transformer.

A commonly used method is to analyze gas and check for the presence of decomposed gas produced due to internal abnormalities to determine the presence or absence of internal abnormalities. Devices such as gas chromatography and mass spectrometry are used for such analysis.

[Problem to be solved by the invention]

Conventional detection of internal abnormalities is carried out using the above-mentioned high-grade analysis equipment, which has the problem of requiring specialized knowledge and time-consuming analysis.

The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method for detecting internal abnormalities in a gas insulated transformer in a short time without requiring specialized knowledge.

[Means to solve the problem]

The internal abnormality detection method according to the present invention measures the odor caused by malodorous substances that occur when SF, gas, or solid insulating material is overheated due to an internal abnormality in a transformer.

[Effect]

In general, gas insulated transformers use SF6 gas as an insulating gas, and solid insulating materials such as cellulose materials such as coil insulating paper, breath pods and wood, and polyethylene terephthalate resin.

Hydrogen sulfide (H2S), methyl mercaptan (CH, SH
), methyl sulfide [(CH3)2S] and methyl disulfide (C14y S-S CH3) are complex decomposition of SF and organic materials, and acetaldehyde (CH, Cl-10) is a cellulose-based material or polyethylene terephthalate resin. These substances are produced due to the decomposition of styrene and the decomposition of styrene.These substances are subject to legal regulations.
It is specified in the ``Offensive Odor Prevention Act,'' and even in extremely small amounts it emits an odor.For example, in the case of an odor that can be easily detected by humans, methyl mercaptan is 0.004
ppm, and is said to be about 0.1 ppm for acetaldehyde.

〔Example〕

Figure 1 shows an example of experimental results showing the basis of this invention.
It shows the amount of aldehydes produced when heated at a temperature of 335°C to 335°C.

From FIG. 1, it can be seen that aldehydes grow as the material decomposes, and the amount produced increases at high temperatures.

In another test, polyethylene terephthalate film, which is used as a coil insulation material for gas-insulated transformers, was found to have an approximately 101,111? was maintained at 400° C. for 30 minutes in N2 gas, and the resulting gas was examined using a gas chromatography mass spectrometer to confirm that styrene, a malodorous substance, was produced. These experiments show that an abnormality inside a transformer can be discovered by detecting foul-smelling substances in SF and gas.

FIG. 2 is a sectional view showing an internal abnormality detection device for gas-insulated electrical equipment in one embodiment of the present invention.

In the figure, (1) is the transformer tank, 2) is the SF and gas sealed in the tank, and (3) is the tank (1).
(4) is a gas circulation pump disposed on the gas circulation passage; (5a) to (5b) are valves disposed on the gas circulation passage; (6n) to (6b) is a flange placed on the gas circulation flow path, (7) is a sensor placed on the gas outlet flow path, and (8> is the tank ()).
This is a gas outlet flow path that communicates with the inside.

Next, the operation will be explained. S in the transformer tank (1)
F, gas (2) is transferred by gas circulation pump (4) to gas inlet flow N (3) → gas circulation pump (4) → valve (5
a) → Flange (6) → Sensor (7) → Flange (6b
)→valve (5b)→gas output channel (8).

When an abnormality occurs in a transformer tank, SF or solid insulating material decomposes and generates decomposition products. Since the SF gas <2> in the transformer tank (1) circulates through the aforementioned path, the decomposition product components flow into the sensor (7) together with the SF s gas and are detected.

Sensor 7) is, for example, a platinum wire coil coated with SnO2, Z
It is an element made by sintering metal oxides such as nO, and is sensitive to malodorous substances such as aldehydes and methyl mercaptan.
Electrons are injected into the device, and the resistance decreases because the free electron concentration increases.

By the way, in the above explanation, the present invention was applied to SF, a gas insulated transformer filled with gas.
Other gas-insulated electrical equipment also suffered 71% due to internal abnormalities.
! It goes without saying that this law can be applied to cases where odor substances are generated.

〔Effect of the invention〕

As described above, in this invention, malodorous substances with high detection sensitivity are used as the target components for abnormality detection, so that internal abnormalities in gas-insulated electrical equipment can be detected easily and with high sensitivity.

[Brief explanation of drawings]

Figure 1 shows an example of experimental results showing the basis of this invention.
The figure is a sectional view showing an example of a gas insulated transformer internal abnormality detection device. In FIG. 2, (1) is a transformer tank, (4) is a gas circulation pump, and (7) is a sensor.

Claims (1)

[Claims] (1) Hydrogen sulfide, methyl mercaptan, methyl sulfide generated by thermal decomposition of SF_6 gas and solid insulating materials,
A gas insulated electric appliance, characterized in that odors caused by malodorous substances such as methyl disulfide, acetaldehyde, or styrene are detected by disposing a sensor sensitive to malodorous substances in a gas circulation flow path that communicates with the main body of the gas-insulated electrical equipment. Method for detecting internal abnormalities in insulated electrical equipment.