JPH0667109B2 - Method and apparatus for failure diagnosis of gas filled electric equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a gas-filled electric machine in which a device main body is housed in a tank together with an insulating gas for insulation or cooling such as a gas-insulated transformer. The present invention relates to a failure diagnosis method and apparatus for monitoring an abnormal state such as local heating of equipment.

(Prior Art) Conventionally, in an electric device such as a transformer, an oil-filled transformer in which an insulating oil is sealed in a tank accommodating a device body for insulation or cooling has been mainstream. However, in the case of an oil-filled transformer, if a failure occurs due to abnormal heating in the tank, the insulating oil ignites and explodes. There is a fear. In particular, as in recent years, the demand for electric power has greatly increased, and along with it, it is difficult to secure a place for installing these electric devices, and therefore transformers are often installed in the vicinity of urban areas or underground of buildings. In this way, due to changes in the installation environment, transformers with higher safety that are free from the risk of fire or environmental damage have been demanded. In order to meet these demands, we have recently adopted a gas-insulated transformer that is less likely to cause a fire in the event of an accident than insulating oil, and is smaller and lighter than the oil-filled type and has excellent reliability and disaster prevention. Is becoming popular. This gas-insulated transformer is insulated in the tank that houses the equipment body, and instead of the conventional insulating oil, it is filled with an inert, non-combustible insulating gas such as SF ₆ gas as a cooling medium for insulation or cooling. It is the one. Therefore, there is no risk of fire even if the temperature inside the tank becomes abnormally high due to a failure, and the environment is not adversely affected, making it suitable for installation in urban areas or underground buildings.

(Problems to be Solved by the Invention) On the other hand, it is a problem that electric equipment such as these transformers must be avoided from an operation stop due to an accident from the viewpoint of stable power supply. It can be understood from the importance of electric power energy at present that the interruption of electric power supply due to an accident, that is, a power outage has a great adverse effect on various fields such as society and economy. In the case of transformers in particular, leakage magnetic flux causes eddy currents in the structural members that make up the tank and device body,
There are many causes of abnormalities such as abnormal heating locally, heat generation due to incomplete contact of conductor connection part, or heat generation due to insulation deterioration caused by partial discharge. This leads to a major accident and the interruption of power supply. Therefore, it is indispensable to constantly monitor the occurrence of abnormalities in these electrical devices, detect them at a minor precursory stage, and take appropriate measures to prevent them from causing accidents. is there. As a result, the reliability of electric equipment is further enhanced and a stable supply of electric power is achieved.

In a conventional oil-filled transformer, when a slight local heating occurs as a precursory stage leading to an accident, the insulating oil that contacts the part is heated, and when the temperature reaches 150 to 200 ° C, the insulating oil Pyrolyzes to generate a specific decomposition gas. The failure diagnosis of the oil-filled transformer can be performed by constantly or periodically monitoring the generation of this decomposed gas.

On the other hand, considering a gas-insulated transformer that has recently been put into practical use and has excellent disaster prevention properties, even in this gas-insulated transformer, as with the oil-filled transformer, the insulating gas filled in the tank is constantly or regularly used. It has been attempted to make a fault diagnosis by analyzing the above. However, SF ₆ gas, which is used as a connection medium for gas-insulated transformers, is non-toxic and is very stable thermally and is the optimum gas as an insulation medium. Considering this, a slight local heating does not cause thermal decomposition, and therefore the analysis of the insulating gas itself cannot reliably perform abnormality monitoring. Further, as a function of such an abnormality monitoring means, it is necessary not only to monitor only a portion where the local heating is predicted in advance but also to monitor the local heating at a portion where the local heating cannot be predicted. Things like gas-insulated transformers are manufactured by designing sufficient thermal strength and insulation strength in advance, but it is not only possible to ignore failures that cannot be predicted, but rather Preventing such unpredictable failures greatly contributes to reliability improvement.

In view of the above points, the present invention does not affect the inherent performance such as insulation performance and cooling performance, monitors a slight abnormal state such as local heating, and reliably prevents an accident from occurring. An object of the present invention is to provide a failure diagnosis method for a gas-filled voltage device and a device therefor.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention, together with the device body,
An insulating gas with thermal stability such as SF ₆ is stored in the tank, and an appropriate amount of a detection gas such as CFC gas that causes a thermal decomposition reaction at a specific temperature is mixed into the insulating gas in the tank. It is characterized in that a means for detecting a thermal decomposition product associated with thermal decomposition of gas is provided.

(Operation) In this way, when local heating occurs in the tank and a precursory phenomenon of failure occurs, the insulating gas itself does not cause a thermal decomposition reaction, but the detection gas mixed in the insulating gas has a thermal decomposition reaction starting temperature. By setting the temperature to be substantially the same as the local heating temperature, the detection gas undergoes a thermal decomposition reaction, and the abnormality of the electric device can be monitored by detecting the thermal decomposition product generated thereby.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings in the case of a gas-insulated transformer. In FIG. 1, reference numeral 1 denotes a tank which accommodates a device body 5 including an iron core 2, a winding 3 wound around the iron core 2, and clamps 4a and 4b for tightening the upper and lower sides of the iron core 2. The tank 1 is filled with an apparatus body 5 and an inert or non-combustible insulating gas 6 such as SF ₆ gas for insulation or cooling. Further, the insulating gas 6 is enclosed at a high pressure of, for example, 4 to 5 atmospheres in order to increase its insulating strength, and therefore the tank 1 is configured as a pressure vessel. A cooling device 7 is attached to the side wall of the tank 1 via ducts 8a, 8b and the like, and the insulating gas 6 heated in the tank 1 is circulated by a pump 9 to cool the device body 5 and the like. . Reference numerals 10a and 10b are lead bushings for pulling out the leads from the winding 3 to the outside. In the present invention, the insulating gas 6 sealed in the tank 1 is mixed with a detection gas 11 for abnormality monitoring different from the insulating gas 6. For example, Freon 113 (CCl ₂ FCClF ₂ ) is used as this detection gas.
It is mixed to the extent that it does not affect the insulation performance and cooling performance, for example, about 5 PPM. As a characteristic of CFC113, the thermal decomposition reaction initiation temperature is about 300 ° C by itself, but in the coexistence with metals, oils or other insulators, the thermal decomposition reaction initiation temperature drops to about 200 ° C or less. It has the characteristic that Reference numeral 12 is a pipe for monitoring decomposition gas attached to the lower part of the tank 1, and the valve 13 is normally closed to keep the tank 1 sealed.

Next, the operation of the present invention will be described. During normal operation of the transformer, the main body 5 such as the iron core 2, the winding 3, the clamps 4a and 4b, and the other tank 1 by the insulating gas 6 filled in the tank 1.
Insulate the internal structure and pump the insulating gas 6
A necessary example of the device main body 5 is performed by circulating it to the cooler 7. Due to magnetic flux leaking from the iron core during operation, eddy currents are generated in the structural members that make up the tank and the main body of the equipment, heat is generated due to incomplete contact of conductor connection parts, or heat is generated due to insulation deterioration, etc. Heating occurs. This local heating occurs, and its temperature leads to the occurrence of an accident.
When the temperature reaches approximately 0 to 200 ° C., the insulating gas 6 itself does not undergo a thermal decomposition reaction, but the detection gas (CFC 113) 11 circulating in the tank 1 mixed in the insulating gas 6 causes a thermal decomposition reaction. The reaction at this time is as follows.

_{(1) 2CCl 2 F-CClF} 2 → CCl 3 F + CClF 2 -CClF-CClF 2 (2) CCl 2 F-CClF 2 + RCH 2 -CH 3 → RCHCl-CH 3 + CHClF-CClF 2 pyrolytic reaction The higher the temperature, the more violently the reaction becomes, thereby generating decomposition gas which is a thermal decomposition product. Therefore, the valve 13 of the pipe 12 is opened periodically, the insulating gas 6 is extracted into the tank 1, and the decomposition gas component based on the thermal decomposition reaction of the detection gas (CFC 113) 11 mixed therein is analyzed. By detecting it, the local heating generated in the tank 1 can be detected at a minor failure sign stage before an accident occurs. As a result, inspections and operation switching are performed according to the degree of the abnormal state to prevent an accident from occurring. The sensitivity of this abnormality monitoring, that is, how many times the local heating rises before it is determined to be abnormal, is the detection gas (CFC 11).
3) If the concentration of 11 in the insulating gas 6 is changed, or if another detection gas having a different thermal decomposition reaction starting temperature is mixed in the insulating gas 6, the detection level is set to a specific temperature as required. It is possible.

FIG. 2 shows an apparatus for carrying out the failure diagnosis method according to the present invention. A monitoring apparatus 14 having a gas detecting and analyzing function is attached to the bottom of the tank 1 via a pipe 12. It is possible to detect the local heating generated in the tank 1 before the occurrence of the accident by constantly or periodically extracting the insulating gas 6 and analyzing the decomposed gas component by the monitoring device 14.

Further, in the failure diagnosis method of the present invention, the detection gas 11 mixed in the insulating gas 6 circulates with the insulating gas 6 to every corner of the tank 1, so that the local heating cannot be predicted in advance. Even if local heating occurs, it can be reliably detected. However, in order to further identify and detect the local heating occurrence point which is judged to be abnormal, in addition to the method of the present invention, a special method that physically and chemically changes at a specific temperature that has been conventionally used. It may be used in combination with a means using a substance.

In the above embodiment, the general gas-insulated transformer has been described as a system in which both insulating and cooling functions are provided in the insulating gas, but the present invention provides the insulating and cooling functions in separate gases. It is also possible to implement a separate type gas-insulated transformer. Furthermore, as one of the conventionally known gas-insulated transformers, SF ₆ gas has an insulating function,
It is known that there is an evaporative cooling type gas-insulated transformer in which the Freon gas has a cooling function and both gases are mixed in the same tank.

However, the contents of the evaporative cooling type gas insulated transformer and the present invention can be clearly distinguished. That is, the former one is one in which the CFC gas enclosed in the tank evaporates due to the heat of the device main body, and the heat of the device main body is taken as the latent heat of evaporation at that time to cool it, and the thermal decomposition product of the CFC gas as in the present invention. No means for analyzing is taken, and the failure diagnosis function of the present invention is not provided at all.
On the other hand, according to the present invention, the amount of the chlorofluorocarbon filled in the tank 1 is extremely small compared to the insulating gas, and does not have a function of evaporating and cooling by the heat of the device body.

In addition, in the above-described one embodiment of the present invention, the case of the gas-insulated transformer as the gas-filled electric device has been described, but it goes without saying that the invention can be applied to other gas-insulated electric devices such as the gas-insulated switchgear gas-insulated busbar. The present invention can also be applied to a gas filled electric device of a type in which an insulating gas is filled in a tank for purposes other than insulation, for example, mainly for cooling.

Furthermore, if the explanation is added, the detection gas used in the present invention is not limited to Freon 113 (CCl ₂ FCClF ₂ ), and the specific temperature, that is, the thermal decomposition reaction initiation temperature, is set according to any setting of the detection level. Different CFC-based gas,
Alternatively, it is possible to use a gas of another system.

〔The invention's effect〕

As described above, according to the present invention, the device body is housed in the tank together with the insulating gas, and the insulating gas in the tank is mixed with the detection gas that causes a thermal decomposition reaction at a specific temperature, and the heat of the detection gas is increased. Since a means for detecting thermal decomposition products accompanying decomposition is provided, it does not affect the inherent performance such as insulation performance and cooling performance at all, and monitors minor abnormal conditions such as local heating to ensure reliable operation. It is possible to provide a failure diagnosis method for a gas filled electric device and an apparatus therefor capable of preventing an accident from occurring.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a gas-insulated transformer showing a failure diagnosis method according to an embodiment of the present invention, and FIG. 2 is a sectional view of a gas-insulated transformer also showing a failure diagnosis device. . 1 ... Tank, 2 ... Iron core 3 ... Winding, 5 ... Equipment body 6 ... Insulating gas, 11 ... Detection gas 12 ... Pipe, 13 ... Valve 14 ... Monitoring device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location H02H 7/04 C 7509-5G (72) Inventor Yasuaki Ishioka 2 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 Incorporated company Toshiba Hamakawasaki factory (72) Inventor Toshiro Toshitsuro 1 Komukai Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa Inside Toshiba Research Institute, Inc. (56) Reference JP-A-58-155323 (JP, A) ) JP-A-54-21551 (JP, A) Actually developed 59-111430 (JP, U)

Claims (3)

[Claims] 1. A device main body is housed in a tank together with an insulating gas, and a detection gas that causes a thermal decomposition reaction at a specific temperature below the decomposition temperature of the insulating gas is mixed into the insulating gas in the tank, and the detection gas is detected. A failure diagnosis method for a gas-filled electrical device, which detects an abnormal state by detecting a thermal decomposition product associated with thermal decomposition of gas. 2. A failure diagnosis device for a gas-filled electrical device, wherein a device body is housed in a tank together with an insulating gas, and a thermal decomposition reaction is carried out in the insulating gas in the tank at a specific temperature lower than the decomposition temperature of the insulating gas. A failure diagnosis device for a gas-filled electric device, comprising a monitoring device which mixes a generated detection gas and detects a thermal decomposition product accompanying the thermal decomposition of the detection gas. 3. The fault diagnosis device for gas filled electric equipment according to claim 2, wherein the gas filled electric equipment is a gas insulation transformer.