JPH04183210A - T-type bushing - Google Patents

Abstract

PURPOSE:To realize efficient withstand voltage test by connecting a cable with one end of a central conductor buried in an insulation layer of a T-type bushing, forming the other end of the central conductor of a hollow shaft, and placing a retractable disconnecting rod therein. CONSTITUTION:An L-type central conductor 2 is buried in a T-type insulation layer 1 thus forming a T-type bushing 36. A cable 40 connected with one and of the conductor 2 and a cylindrical through-hole is made on the other side of the conductor 2 from the at the left end of the insulation layer 1 to a right side recess 2d3. A disconnecting rod 11 movable to the right and left is then inserted along a plurality of phosphor bronze contact pieces 17 on the inside of the through-hole. The disconnecting rod 11 is inserted by removing a blind cover 47 at a blind wire part 43 on the right end of the through-hole, a stress cone 46, a disconnecting rod fixing metal 12, and the like. When power is conducted, the blind wire part 43 is assembled and the tip of the disconnecting rod 11 is pushed out and abutted on the seat 15 of a conductor 39 in machine room whereas when withstand voltage test is made on the side of the cable 40, the blind wire part 43 is dismantled and the disconnecting rod 11 is retracted. According to the constitution, withstand voltage test can be carried out easily only on the cable side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a T-shaped bushing used in a cable connection section of a gas-insulated switchgear or the like.

(Prior Art) In FIG. 6, which shows an example of a gas insulated switchgear equipped with a conventional T-shaped bushing, a box body is provided with a door 31a on the left side of the figure, which is the front side, and a door 31b on the right side. 31, a partition 31c is vertically provided near the front of the center, and a partition 31e is vertically provided near the rear of the center, and at the lower ends of these partitions 31c and 31e, a partition 31d
are provided horizontally and these partitions 31c, 31d,
The interior surrounded by 31e is an airtight container.

Furthermore, a partition 3 is provided on the lower surface of the ceiling plate 31f near the center back.
1g is erected, and the lower end of this partition 31g and the partition 31
A partition 31b is provided between the rear surfaces of c, and as a result, the box body 31 has a low pressure chamber 32A at the front of the partition 31c, an equipment room 31B at the rear of the partition 31c, and a cable room 32C at the rear of the partition 31e. , and is divided into a disconnector chamber 32D at the lower center of the ceiling plate 31f.

Among these, in the low pressure chamber 32A, a disconnector operating mechanism 33a is mounted on the upper front surface of the partition 31c, a circuit breaker operating mechanism 34a is mounted on the central front surface of the partition 31c, and a disconnector operating mechanism 35a is mounted below this. It is attached via.

Next, in the center of the ceiling plate 31f, a T-shaped bushing 36A, which will be described in detail later, is provided with its lower part passing through a hole provided in the ceiling plate 31f, and at the rear of the upper part of the partition 31c, a disconnector with a grounding blade is provided. 33 is installed, this disconnector 3
The upper pole of the disconnector 33 is connected to the lower end of the T-shaped bushing 36A by a conductor, and the lower pole of the disconnector 33 is connected to the upper end of the bushing 31b1 extending vertically through the middle part of the partition 31b.

Further, a vacuum breaker 34 is attached to the intermediate rear surface of the partition 31c, and the upper pole of the vacuum breaker 34 is connected to the lower end of the bushing 31b above the vacuum breaker 34.
The lower terminal of the current transformer 37 is connected to the upper terminal of the current transformer 37 attached to the rear of the vacuum circuit breaker 34, and the lower terminal of the current transformer 37 is connected to the partition 31c through an insulator 38 fixed to the box body 31. It is connected to the upper pole of a disconnector 35 with a grounding device attached to the rear surface of the lower part, and below this disconnector 35, a grounding switch 38 is provided on the upper surface of the partition 31d.

Furthermore, the lower pole of the disconnector 35 is a conductor 39 bent into a substantially rectangular shape.
It is attached to the upper end of this rear partition 31e via and connected to the front end of a T-shaped bushing 36B, which will be described in detail later.
A voltage detecting insulator 5 is attached to the lower surface of the ceiling plate 31f behind the partition 31g.

On the other hand, a high-voltage cross-linked polyethylene cable (hereinafter referred to as cable) 40 rising from the floor where the gas-insulated switchgear is installed is connected to the lower end of the T-shaped bushing 36B, as will be described in detail later, and is attached to the ceiling plate 31f. A cable (not shown) connected to an adjacent panel (not shown) is also connected to one side of the upper part of the T-shaped bushing 36A, and sulfur hexafluoride gas is sealed in the disconnector chamber 32D and the equipment chamber 32B. .

Next, FIG. 7 is an enlarged detailed longitudinal cross-sectional view of the T-shaped bushing 36B.

In the same figure, the T-shaped bushing 36B includes a substantially T-shaped insulating layer 41 cast-molded with epoxy resin and having openings formed at the bottom and right side, and a substantially T-shaped insulating layer 41 that is pre-embedded as a filler metal inside this insulating layer 41. a rectangular center conductor 42, a blind plug part 43 attached to the opening on the right side and described in detail later, and a cable connection part 44 that holds the cable 40 inserted into the lower opening and connects the core wire to the center conductor 42. It is roughly composed of.

Of these, a mounting surface 41b having a cross-sectional shape is provided on the left side of the insulating layer 41 together with a recess 41a formed on the outer periphery, and a female threaded fillet (not shown) is embedded in this mounting surface 41b. , is airtightly fixed to the inner surface of the partition 31e via an O-ring 41c with a bolt (not shown).

Further, a conductor 39 is fixed to the left end of the center conductor 42 with a bolt, and a recess 42 having a U-shaped cross section is provided at the right end of the center conductor 42.
d1 is formed, and a female screw 41 is inserted at the bottom of this recess 42d1.
Similarly, the cable connection portion 44 at the lower end of the center conductor 42 is also provided with a recess and a female screw 41d2, and the bottom of the female screw 41d2 is further provided with a flower pot-shaped recess 42.
d3 are formed respectively.

Next, in the blind plug part 43, there is a concave part 42 at the right end of the center conductor 42.
A spacing cylinder 45 having a U-shaped cross section is loosely inserted into the spacer dl, and a stress cone 46 having a substantially truncated cone shape is further to the right of this spacing cylinder 45.
is inserted into the inner periphery of the insulating layer 41 while being pressed by a pressing member to be described later, and a filler metal 46a having a chevron-shaped cross section is embedded in advance on the right side of the stress cone 46, and the insulating layer 41
A lid 47 having a generally convex cross section is fixed to the right side of the lid 47 with a bolt, and a suppressing member 48 made of a bolt, a compression coil spring, or the like is installed in advance inside the lid 47.

On the other hand, a plurality of copper wedges 44a are inserted into the cable connecting portion 44 around the outer periphery of the core wire at the tip of the cable 40 inserted inside, and a screw is formed on the upper half of the outer periphery on the lower side of the wedge 44a. A cylindrical suppression tube 44b with a substantially convex cross section is screwed together, and a cylindrical stress cone 49 with a chevron-shaped half cross section is inserted into the outer sheath of the cable 40 further below the pressure tube 44b. There is. Furthermore, a cylindrical protection tube 50 (details omitted) is inserted in advance below the stress cone 40, and a pressing member made of a coil spring, bolt, etc. (not shown) is attached to the inside of this protection tube 50. The protective tube 50 is fixed with bolts through a filler metal embedded in the lower end of the insulating layer 41, and as a result, the stress cone 40 is pressed upward in the figure by a pressing member inside the protective tube 50. .

Therefore, the T-shaped bushing 36 configured in this way
In B, the cable 40 is connected to the T-shaped bushing 36B.
The conductor 39 is connected to the disconnector 38 inside the equipment room 32B via the center conductor 42 embedded inside the equipment room 32B.

By the way, in an insulated switchgear as shown in Fig. 6, when newly installed or buried, the cable 4 installed on the installation floor is
A withstand voltage test of 0 is conducted, and at that time, a withstand voltage test using direct current is adopted due to the capacitance between ground and ground.

(Problem to be Solved by the Invention) By the way, in an insulated switchgear that has been in operation for many years, copper powder is generated when the disconnector 35 is turned on and off, and also when the disconnector 35 is turned on and off.
The decomposition products of sulfur hexafluoride gas due to the arc generated when 5 is turned on and off are deposited on the surface of the disconnector. Then, performing a DC withstand voltage test on this insulated switchgear will be harsher than applying an AC voltage, so in this type of equipment, the equipment inside the box 31 must be disconnected from the test power supply by agreement between the manufacturer and the user. It is supposed to be.

However, the T-shaped bushing 3 configured as shown in FIG.
6B, if the stress cone 46 inside the blind plug part 43 is removed from the cable for withstand voltage test and connected as in the cable connection part 44, the DC voltage for the test will be applied to the center conductor 42 and the conductor. 39 to the disconnector 35 and the like in the equipment room 32B.

Therefore, the cable 4 connected to the cable connection part 44
It is also possible to perform a pressure test by removing 4, but that would be time-consuming.

Therefore, an object of the present invention is to obtain a T-shaped bushing that can be easily separated from the equipment inside the box during a pressure test.

[Structure of the Invention] (Means and Effects for Solving the Problem) The present invention provides a T-shaped bushing in which a center conductor is embedded in an insulating layer and a cable connection portion is provided on one side of the end of the center conductor. The other side of the center conductor is a hollow shaft, and a disconnecting rod is provided inside the hollow shaft, the outer periphery of which contacts the hollow shaft and can move forward and backward in the axial direction.This allows the disconnecting rod to be retracted during cable pressure tests. This is a T-shaped bushing that allows devices connected to the other side of the center conductor to be disconnected, making it easier to conduct voltage resistance tests on cables.

(Example) Hereinafter, one example of the T-shaped bushing of the present invention will be described with reference to the drawings. However, parts that overlap with those in FIGS. 6 and 7 are given the same reference numerals and their explanation will be omitted.

In the figure, a center conductor 2 buried inside an insulating layer 1
The left end of the center conductor 2 is located inside the left end of the insulating layer 1, and a cylindrical through hole is provided at the center of the axis up to the recess 2d3 on the right side. An annular groove is formed on the inner periphery, and an annular O-ring receiver 14 is embedded in this groove in advance. An O-ring groove is formed on the inner periphery of this O-ring receiver 14, and the O-ring 14a is inserted into the groove. has been done.

On the other hand, inside the through hole, there is a female thread in the large diameter part on the right end.
A round rod-shaped disconnection rod 11 formed with is inserted from the right side,
A groove 19 is formed on the lower surface of the large diameter portion at the right end of the disconnection rod 11 .

Furthermore, a pair of multi-contacts 17 made of a phosphor bronze plate are inserted into the inner periphery of the through hole of the center conductor 2 in a cylindrical shape by being engaged with grooves (not shown) provided in the inner periphery of the through hole. , a groove with a semicircular cross section is formed in an annular shape near the right end of the through hole,
A C-shaped retaining ring 18 is inserted into this groove, and a key 20 is embedded from the groove into which the C-shaped retaining ring 18 is inserted to the right end.

Furthermore, the disconnection rod fixture 12, which has a groove 12a at the right end and a thread at the left end, is loosely fitted into the recess 2dq at the right end, and the male thread at the left end is connected to the right end of the disconnection rod 11. A retainer plug 13 is screwed onto the female thread Ila and has a groove 13a on the right side and a female thread (not shown) formed on the right end of the disconnecting rod fixing device 12 from the right side. Similarly to FIG. 7, the spacer tube 45 and the stress cone 4
6 and a lid 47 are attached.

On the other hand, on the right side of the conductor 39 disposed in the equipment room inside the partition plate 31e to which this T-shaped bushing is fixed, there is a copper seat 15 that has a U-shaped longitudinal section and an annular shape in the right side view (not shown). is fixed with bolts, and a multi-contact 16 having the same shape as the multi-contact 17 mounted on the inner periphery of the center conductor 2 is mounted on the inner periphery of the seat 15.

Now, in the T-shaped bushing configured in this way, when conducting a DC withstand voltage test of the cable 40 connected to the equipment inside the box via this T-shaped bushing, first,
A blind lid 47 that constitutes the right blind stopper portion 43. After removing the stress cone 46, disconnecting rod fixture 12, etc., the same parts as those constituting the cable connection part 44 in FIG. As shown in the figure, this is done by incorporating it together with a cable 30 for connecting to a voltage resistance tester.

On the other hand, normally, as shown in FIG. 3 and FIG. 4(b) which is a partial detailed view of FIG. By incorporating the blind plug part 43, the left end of the disconnection rod 11 is projected from the insulating layer 1 and fitted into the inside of the seat 15.

Also, if the cable 20 that connects to the added gas-insulated switchgear is connected to the blind plug part 43 as shown in FIG. Remove the same parts as those constituting the cable connection part 44 shown in FIG. 1 and insert the fixture 2 shown in FIG. 4(c).
1 and the cable 20 together and configured as shown in FIG. 5, for example, this can be easily handled.

Therefore, in the T-shaped bushing configured in this way, it is possible to disconnect the cable from the equipment room to which the T-shaped bushing is attached and which is filled with insulating gas.
This can be done by inserting and removing the disconnection rod from the blind stopper side of the T-shaped bushing without removing the cable, resulting in a T-shaped bushing that allows for easy pressure testing of cables.

In the above embodiment, a groove 19 is provided in the large diameter portion of the right end of the disconnecting rod 11, and a key 20 that fits into the groove 19 is also embedded in the right end of the through hole of the center conductor 2. ,
The contact pressure between the multi-contact 17 and the disconnection rod 11 is high, so even when the male thread 12a of the fixture 12 is inserted, the disconnection rod 11
It can be omitted if the is not rotating.

[Effects of the Invention] As described above, according to the present invention, the center conductor is embedded in the insulating layer,
In this T-shaped bushing in which a cable connection part is provided on one side of the end of the center conductor, the other side of the center conductor is a hollow shaft, and the outer periphery is in contact with this hollow shaft and moves back and forth in the axial direction. By providing a freely movable disconnecting rod, the voltage resistance test of the cable was performed by disconnecting the disconnecting rod, so that it is possible to obtain a T-shaped bushing that can easily conduct the cable resistance test.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an embodiment of the T-shaped bushing of the present invention, and Fig. 2 is a diagram showing the action of the T-shaped bushing of the present invention, showing the disconnection state of the disconnection rod when testing a cable. 3 is a partially broken sectional view showing the action of the T-shaped bushing of the present invention, and FIG.
The figure is a partial detailed view showing the function of the T-shaped bushing of the present invention.
Fig. 5 is a diagram showing the different functions of the T-shaped bushing of the present invention, Fig. 6 is a diagram showing an example of a gas-insulated switchgear equipped with a conventional T-shaped bushing, and Fig. 7 is a diagram showing the conventional T-shaped bushing. FIG. 1...Insulating layer 2...Center conductor 11...Disconnecting rod 40...Cable (8733) Agent Patent attorney Yoshiaki Inomata (and others)
1 person) Figure 2 Kaya 3 Menbōki 51! I Multi-Ishi 6 Figure

Claims (1)

[Claims] In a T-shaped bushing in which a center conductor is embedded in an insulating layer and a cable connection portion is provided on one end of the center conductor, the other side of the center conductor is a hollow shaft; A T-shaped bushing characterized in that a disconnecting rod is provided inside the hollow shaft, the outer periphery of which is in contact with the hollow shaft, and is movable in the axial direction.