JPH0140568B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to gas-insulated or oil-insulated sealed electrical equipment (hereinafter referred to as sealed electrical equipment).
In particular, it is designed to make it easy, highly reliable, and economical to conduct on-site withstand voltage tests of equipment and to configure bypass circuits in the event of equipment failures. In recent years, as the demand for electricity has increased in urban centers and surrounding areas, it has become difficult to secure land for substations. One way to deal with this is to use sealed electrical equipment that houses high-voltage circuits, such as disconnectors, disconnectors, or grounding devices, in a sealed container filled with an insulating medium such as insulating gas or insulating oil. Compared to the insulation type, the structure is smaller and the filling part is not exposed. In order to take advantage of the fact that the live parts are not exposed, they are often configured with cable power receiving. By the way, the sealed electrical equipment is not subject to laws and regulations.
JEC standards (IEEJ Electrical Standards Committee Standards),
Other related standards require that a withstand voltage test be conducted, but in particular Article 14 of the Electrical Equipment Technical Standards (Ordinance No. 61 of the Ministry of International Trade and Industry) requires that a so-called on-site withstand voltage test be conducted at the time of installation. This is necessary, and this on-site withstand voltage test must be conducted including the gable. However, when the cable to be connected is long, it is generally impossible to perform the on-site withstand voltage test due to the limitations imposed by the capacity of the test transformer. The above-mentioned electrical equipment technical standards permit the electrical equipment technical standards to conduct the withstand voltage test and the DC withstand voltage test of the cable separately. In this case, as mentioned above, since sealed electrical equipment usually does not have exposed live parts, the withstand voltage test is generally carried out according to the following procedure. That is, a test cable is attached to the cable head of a sealed electrical device, and an alternating current withstand voltage test is performed on the main body of the sealed electrical device. Next, remove this test cable and install the product cable in its place.
Open the disconnect switch at the entrance of the sealed electrical equipment. After recovering the insulating medium of the sealed electrical device, the sealed electrical device is opened to expose the charging portion and connected to a DC power supply. After that, it is evacuated, filled with insulating medium again, and the product cable is tested for DC withstand voltage. After performing a DC withstand voltage test on the product cable, the sealed electrical equipment is restored to its original state by performing the exact opposite of the above procedure. In addition,
An example of the procedure for DC withstand voltage testing of the product cables mentioned above is shown in Figure 1 for SF ₆ gas insulated equipment. In addition, in the case of the oil insulation method, the procedure is almost the same except that the type of insulating medium is different. In this way, on-site withstand voltage tests for sealed electrical equipment are not only extremely troublesome and time-consuming, but also very uneconomical. The above work requires the utmost care to prevent these intrusions. In addition, conventionally, when attaching a test cable or product cable to the cable head, the sealed container was opened and connections were made, followed by sealing, vacuuming, filling with insulating medium, etc. Recently, there has been an increasing demand for the so-called slip-on method, which allows cables to be attached and detached without opening the sealed container. In the case of such a slip-on method, it is not only necessary to avoid the troublesome work of attaching and detaching the test cable or product cable as described above in order to maintain the reliability of the joint surface, but also to avoid the troublesome work of attaching and detaching the test cable or product cable as described above. Even if it becomes possible to attach and detach the cap, the sealed container must be opened for the withstand voltage test, and as a result, the effectiveness of the slip-on method is significantly diminished. Next, if a failure occurs in the sealed electrical equipment or any other sealed electrical equipment or transformer connected to it, it is practical to prepare a replacement equipment immediately or to replace it. Since it is quite difficult to do so, as a temporary measure until then, only the failed equipment is disconnected and a bypass circuit is used to ensure power transmission. In this case as well, since the live part is not exposed to the air, a connection part for the emergency cable is provided in advance. In this case, the procedure for attaching and detaching the emergency cable requires almost the same procedure as that for attaching and detaching the cable during the above-mentioned withstand voltage test, so there are the same drawbacks as described above, and it is difficult to expect a quick operation. In addition, if the slip-on method is adopted, the complexity of the work will be relieved, but it is necessary to install a cable head for attaching and detaching the slip-on cable in the sealed electrical equipment in advance, which increases the size of the equipment and impairs economic efficiency. There are drawbacks. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to enable easy, highly reliable, and economical withstand voltage testing of sealed electrical equipment and configuration of a bypass circuit while a product cable is attached to a cable head. The purpose of this is to have a energizing contact that penetrates the airtight container and is slidably and airtightly arranged to make contact with and disconnect from the high voltage circuit, and a conductor that is connected to the energizing contact inside and an external conductor. This is achieved by comprising a charging bushing made of an insulating support and detachably attached to the charging contact. Embodiments of the present invention will be described in detail below with reference to FIGS. 2 to 6. Figure 2 is a cross-sectional view showing an example of a sealed electrical device, and Figure 3 is a single-line diagram of the same, with the transformer (not shown) exposing live parts to the atmosphere through bushings (not shown). It is directly connected to this sealed electrical equipment without any need to do so. A grounded closed container 1 is filled with an insulating medium 2 such as SF ₆ gas or insulating oil. A cable head 3 is attached to the inlet side of the hermetic container 1, and a sheath disconnector 4a, a disconnector 4b,
A high voltage circuit 4 such as a grounding device 4c is housed.
5 is a cable connected to the cable head 3. Further, a charging contact 6 is attached to the inlet side of the closed container 1, that is, to the section A in FIG. As shown in detail in FIG. 4, this charging contact 6 penetrates the closed container 1, and its tip is slidable so that it can come into contact with and separate from the high voltage circuit 4 , and is sealed with an O-ring or the like. It is airtightly attached by members 7 and 7a. In addition, the charging contact 6
is prevented from falling into the closed container 1 by a suitable stopper (not shown). On the other hand, as shown in FIG. 5, a charging bushing 8 , which is detachably formed on the base end of the charging contact 6 by a method such as screwing, has a charging contact 6 attached therein. It has a conductor 9 to be connected, and the outside thereof is constituted by an insulating support 10, and the side penetrated into the closed container 1 has the same outer diameter as the energizing contact 6. Next, a withstand voltage test of a sealed electrical device using the above device will be explained. Now, in order to perform an AC withstanding voltage test on the main body of this sealed electrical equipment, attach the conductor 9 of the energizing bushing 8 to the energizing contact 6, and slide the energizing contact 6 so that its tip is connected to the high voltage circuit 4. This state is shown in FIG. At this time, the sealed container 1 and the insulating support 10 of the charging contact 6 or the charging bushing 8 are the sealing member 7,
Since it is sealed by 7a, the insulating medium 2 inside this closed container 1 will not leak to the outside.
In order to prevent the insulating medium from leaking from the joint between the energizing contact 6 and the energizing bushing 8 during attachment and detachment, it is desirable to have at least two rows of seals, the seal members 7 and 7a. The insulating support 1 is used to cover the instability of the seal due to the difference in thermal expansion coefficient between the body 0 and the metal sealed container 1.
It is more reliable if the sealing member 7b is also provided on the joint surface between the insulating support 10 and the hermetic container 1, or the fitting part between the insulating support 10 and the hermetic container 1 is made of metal. After this, the conductor 9 of the energizing bushing 8
By connecting a testing AC power supply device to the base end of the AC power supply and applying power, an AC withstanding voltage test of the main body of the sealed electrical equipment can be performed. If the relative positions of the high-voltage circuit 4 and the energizing contact 6 are not appropriate due to restrictions in their arrangement, the energizing contact 6 and the energizing bushing 8 may be rotated together to bring them into contact with and separate from the high-voltage circuit 4 . It's okay. On the other hand, in order to perform a DC withstand voltage test on the cable 5, if the disconnector 4b of the high voltage circuit 4 is opened, the voltage will pass through the conductor 9 of the energizing bushing 8 , the energizing contact 6, the high voltage circuit 4 , and the cable head 3. A circuit leading to the cable 5 is formed. Therefore, the charging bushing 8
By connecting a DC power supply to the base end of the conductor 9 and applying power, the cable 5 can be tested for DC withstand voltage. In addition, if the length of the cable 5 is short, the DC withstanding voltage test of the cable 5 is not performed, and the AC withstanding voltage test of the sealed electrical equipment and the cable 5 can be performed at the same time. It goes without saying that this can be done using exactly the same method. Next, a case in which a bypass circuit is configured will be described, taking as an example a case where a failure occurs in a transformer and the bypass circuit is connected to a mobile transformer. In this case, the charging contact 6
is attached to the load side of the sealed electrical equipment, that is, to the B part of the container 1 in FIG. In this case as well, the charging bushing 8
If it is attached to the charging contact 6, it becomes possible to bypass the transformer and transmit power from the mobile transformer. In this case , it is necessary that both the charging contact 6 and the charging bushing 8 have a current carrying capacity.
It is necessary that the charging contact 6 and the tulip contact of the high voltage circuit 4 have a current carrying capacity. As described above in detail together with the embodiments, according to the present invention, even in a sealed electrical device with no exposed live parts, withstanding voltage tests and bypass circuit configuration can be performed without opening the sealed container. There is no need for any work such as collecting the insulating medium to expose the live parts, evacuation, or refilling, making the operation easy and highly reliable, and very economical. In addition, there is no need to attach or detach the test cable or product cable to the cable head as in the past, and AC withstand voltage tests on sealed electrical equipment and DC withstand tests on product cables can be performed with the product cables attached. Even in the case of the slip-on method, there is no risk of damaging the joint surface of the cable head. Furthermore, since the energizing contact is directly connected to the grounded sealed container, it does not become a floating electrode and is safe. In addition, it has a very simple structure and is compact, with almost no protrusion from the sealed container. It is extremely economical without sacrificing any of its advantages as a miniature device. Furthermore, this energizing bushing is an emergency component for test equipment or accidents, and is not included in the product price and can be used for multiple sealed electrical devices, making it very economical.

[Brief explanation of drawings]

Figure 1 is a flowchart showing the procedure for conventional DC voltage testing of cables for sealed electrical equipment;
3 is a single line diagram of FIG. 2, FIG. 4 is an enlarged sectional view showing details of section A or B in FIG. 2, and FIG. 5 is a sectional view showing an embodiment of the present invention. A cross-sectional view of the energizing bushing, FIG. 6 is a cross-sectional view showing an aspect during a withstand voltage test. 1 - Airtight container, 2 - Insulating medium, 3 - Cable head, 4 - High voltage circuit, 5 - Cable, 6 - Contactor for charging, 7, 7a, 7b - Seal member, 8 - Bushing for charging, 9 - conductor, 10 to insulating support;

Claims (1)

[Claims] 1. In a device in which a high voltage circuit is housed in a closed container filled with an insulating medium, an energizing contact that penetrates the closed container and is slidably and airtightly disposed to connect to and separate from the high voltage circuit. and an insulating support that has a conductor connected to the energizing contact inside, and at least the outer diameter of the side penetrated by the airtight container is the same as the outer diameter of the energizing contact. What is claimed is: 1. A sealed electric device comprising: a charging contact; and a charging bushing configured to be detachable;