JPH0261125B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas-insulated on-load tap-changing transformer having gas pressure control and monitoring functions in the gas-insulated on-load tap-changing transformer. In recent years, there has been an increasing demand for gas-insulated transformers to make substation electrical equipment nonflammable, downsized, and to reduce construction costs. It is obvious that it is preferable for the tap switch to be gas insulated as well, and in this case, it is also easy to assume that it is economically advantageous to use a vacuum valve as the current breaking element of the switch. be done. An example of the on-load tap switching transformer constructed in this manner will be described below with reference to FIG. The interior of a tank 2 housing a transformer body 1 consisting of an iron core and windings is a gas space 3 filled with high-pressure insulating gas such as SF ₆ . An on-load tap changer 4 associated with the transformer body 1 is also mounted on the tank 2, of which a tap selector 5 is located within this gas space 3. On the other hand, the switching switch 6 of the on-load tap switch 4 uses an insulating tube as a part because the vacuum valve 7 used as the current cutting element is normally designed to be used at atmospheric pressure. The switching switch 6 is intended to operate stably over a long period of time by storing it in an airtight container 8 with separate gas divisions, and by filling the internal gas space 9 with an insulating gas approximately equal to atmospheric pressure. This is what I did. By the way, there is a concern with the gas-insulated load tap-change transformer constructed in this manner that the gas pressure in the gas space 9 inside the closed container 8 housing the switching switch 6 will remain at the original sealed pressure over a long period of time. It is unclear whether this will be maintained or not, and the following changes may actually occur. That is, the closed container 8
Although not shown in the figure, there is a terminal that penetrates a part of the insulating tube and connects the connection lead to the tap selector 5 or the neutral point pushing. is used. Further, the top of the container is provided with a lid necessary for hanging and inspecting the switching switch 6, and a rubber gasket is usually used on the flange mounting surface to maintain airtightness. It is well known that these sealing materials inevitably deteriorate over time due to their material properties, and when this deteriorates and the sealing performance is lost, in the case of the through terminal portion, the gas space 3 is transferred to the gas space 9. Insulating gas may enter, and the gas pressure around the vacuum valve of the switching switch 6 may increase, which may impair the strength of the valve airtight seal. In addition, in the case of a lid gasket, diffusion occurs into the atmosphere, and there is a risk that the insulation performance will drop significantly due to a decrease in the density of the insulating gas such as SF ₆ and moisture intrusion. The present invention eliminates the above-mentioned drawbacks and provides a gas-insulated load tap-change transformer that is equipped with a function that enables early detection and appropriate countermeasures when the airtightness of a container housing a switching switch is lost. The purpose is to obtain. In order to achieve such an object, the present invention maintains the gas pressure in the gas space inside the closed container with independent gas compartments at a level slightly higher than atmospheric pressure at all times, and
A first differential pressure detection device is provided between the gas space in the sealed container and the gas space in the transformer body, and a second differential pressure detection device is provided between the gas space in the sealed container and the atmosphere. This system constantly monitors the sealing performance of the airtight part of the closed container. An embodiment of the present invention is shown in FIG. 2, and its configuration will be explained below. Components that are the same as those of the conventional example shown in FIG. 1 are given the same reference numerals, and their explanation will be omitted. The gas pressure in the sealed container 8, which houses the switching switch and has an independent gas compartment, is maintained at slightly higher than atmospheric pressure (approximately 1.2 atmospheres). A gas pipe 10 is led out from this airtight container 8, connected to a valve 11 and a density switch 12, and branched in the middle, one to the atmosphere via a valve 13, and the other to the tank via a density switch 14 and a valve 15. 2
Connect to the gas space 3 inside. Also density switch 1
4 is provided with a bypass having a valve 16 in the middle, which is opened and closed by a signal from the density switch 12, as shown in the figure. By configuring as described above, the following actions and effects are produced. In other words, the gas space 9 inside the closed container 8 is always maintained at a pressure higher than atmospheric pressure, even if only slightly, so even if the sealing performance is lost in the airtight area at the top of the container, the insulating gas It only leaks into the atmosphere, and it is possible to prevent air from entering the sealed container 8 from the atmosphere. Furthermore, the density switch 12 constantly monitors whether the pressure difference with the atmosphere is maintained properly, and therefore, as mentioned above, if the insulating gas leaks into the atmosphere and the pressure difference decreases, it is immediately detected. Appropriate measures can be taken, such as by issuing an alarm. Next, if the sealing performance of the airtight part of the airtight container 8 is lost in the gas space 3 in the tank 2, the pressure in the gas space 9 in the airtight container 8 will increase, which may impair the strength of the airtight sealing part of the vacuum valve. However, since this can be detected by the density switch 14 that monitors the differential pressure between the gas space 3 and the gas space 9 , appropriate measures can be taken by issuing an alarm in the same manner as described above. In addition, the valve 16 uses a solenoid valve to immediately close the gas space 3 in response to an abnormality detection signal from the density switch 12.
By making it possible to supply insulating gas from the insulating gas to the space 9 , there is an advantage that treatment can be performed automatically without the need for a special gas cylinder. Further, the valve 13 is used to suck in the insulating gas sealed in the gas space 9 when inspecting the switching switch 6. As described above, according to the present invention, it is possible to maintain the pressure in the airtight container, which houses the switching switch and has an independent gas section, at all times to be slightly higher than atmospheric pressure. It is possible to obtain a gas-insulated load tap-change transformer that has high insulation reliability even when the sealing performance of the airtight part of the container is deteriorated without imposing any burden on the gas-insulated load.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional gas-insulated load tap-changing transformer, and FIG. 2 is a sectional view showing an embodiment of the gas-insulated load tap-changing transformer according to the present invention. 1...Transformer body, 2...Tank, 3 ...Gas space in tank, 4...Tap changer on load, 5...
...Tap selector, 6...Switch switch, 7...Vacuum valve, 8...Sealed container, 9 ...Gas space in sealed container, 10...Gas piping, 11, 13, 15...
Valve, 12, 14... switch, 16... solenoid valve.

Claims (1)

[Claims] 1 Consisting of a transformer main body housed in a tank together with insulating gas, and an on-load tap changer having a tap selector and a switching switch electrically connected to the transformer main body, the on-load tap changer The tap selector part is placed in the insulating gas in the tank of the transformer body, and the switch switch part is placed in the insulating gas in an independent sealed container, and the tap selector part is placed in the insulating gas in the tank of the transformer main body, and the switch switch part is placed in the insulating gas in an independent sealed container. A device for maintaining the pressure at a level slightly higher than atmospheric pressure, and a device for detecting the differential pressure between the inside of the sealed container and the atmosphere, and a device for detecting the differential pressure between the inside of the sealed container and the inside of the tank, are further provided. A gas insulated load characterized by being equipped with a device that replenishes insulating gas from a gas space in a tank to a gas space in a sealed container based on an abnormal signal from a device that detects the differential pressure between the inside and the atmosphere. Time tap switching transformer.