JP2509639B2 - Gas insulation switchgear disconnecting device - Google Patents

Description

The present invention relates to a cubicle-type gas-insulated switchgear, and more particularly to a disconnector capable of disconnecting an electric device housed inside from the outside of a metal closed container. Regarding the device.

(Prior Art) A general configuration of a conventional gas-insulated switchgear will be described with reference to FIG. In the figure, a power source is introduced from a transformer (not shown) by a cable head 2 into the metal closed container 1, and a disconnector 4 and an instrument current transformer are provided by a conductor 3.
5, it is introduced to the bus bar 7 through the circuit breaker 6, the disconnector 4, etc. Between the cable head 2 and the disconnector 4, there is provided a withstanding voltage test bushing 9 having an electrode 8 that slides vertically while maintaining airtightness.
Is brought into contact with the conductor 3, and the electrode 8 is normally slid downward so that it is not in contact with the conductor 3. The conductor 3 and the instrument transformer 10 are bolted to each other by a connecting conductor 11.

(Problems to be solved by the invention) When performing a high frequency withstand voltage test or a direct current withstand voltage test of a cable, a voltage is applied from the withstanding voltage test bushing 9. At this time, Since the magnetic flux of the iron core is saturated to increase iron loss, there is a risk of overheating and burning, and it is necessary to disconnect the instrument transformer 10 from the main circuit, that is, the conductor 3. However, with the configuration as shown in the figure, it is necessary to remove the instrument transformer 10 from the metal hermetically sealed container 1 at the time of withstanding voltage test, and after further detaching, the metal hermetically sealed container 1 is filled with an insulating gas, and the test is performed. After the operation, the insulating gas was removed, the instrument transformer 10 was attached to the metal closed container 1, and the insulating gas was charged again.

The present invention has been made in view of the above drawbacks, and an object thereof is to easily and externally connect a device requiring a disconnection from a main circuit during a withstand voltage test without removing it from a metal sealed container. An object of the present invention is to provide a disconnecting device for a gas-insulated switchgear capable of disconnecting quickly.

[Structure of the Invention] (Means for Solving Problems) The present invention relates to a gas-insulated switchgear in which an instrument transformer for disconnecting from a main circuit during a withstand voltage test is housed inside a metal airtight container enclosing an insulating gas. In the disconnecting device of the device, a connecting conductor formed of an elastic material, one end of which is electrically connected to the primary terminal of the instrument transformer and the other end of which is in contact with the main circuit, and the main circuit of the other end of the connecting conductor. The operating shaft has one end insulated and connected to the side opposite to the surface in contact with the surface, and is formed of a shape memory alloy material.When the operating heat is generated, the operating shaft is operated to make the connecting conductor and the main circuit non-contact. It is provided with a directional memory element and a coil which causes the bidirectional memory element to generate heat by an electromagnetic induction action during a withstand voltage test.

(Operation) When the voltage transformer is disconnected from the main circuit during the withstanding voltage test, if the coil is energized by an external power source, the coil of the bidirectional element heats up due to electromagnetic induction through the operation shaft. When the bidirectional element exceeds the reverse transformation point due to this heat generation, it tries to return to the original state, expands in opposition to the elastic force of the connecting conductor, and moves the operating shaft upward. This upward movement disconnects the connecting conductor from the main circuit. Also, when the energization of the coil is stopped, the temperature of the bidirectional element drops,
When the temperature becomes lower than the reverse transformation point, it contracts, so that the operating rod moves downward due to the elastic force of the connecting conductor, and the connecting conductor comes into contact with the main circuit again.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.
Note that the same parts as those in FIG. 3 are denoted by the same reference numerals, and redundant description will be omitted. In FIG. 1 and FIG. 2, one end of a leaf spring-shaped connecting conductor 13 is fixed to the instrument transformer 10 mounted inside the metal closed container 1, and the other end of the connecting conductor 13 is It is always in contact with the conductor 3 due to the elastic force.
On the non-contact side of the connecting conductor 13 with the conductor 3, a disconnecting device
The lower ends of 14 operation shafts 15 are connected. This operating axis 15
Is a shaft portion 16 whose side connected to the connecting conductor 13 is formed of an insulating material.
And a shaft portion 18 formed of steel material and provided with a collar 17 in the middle, are integrally formed, and are attached to the metal closed container 1 to guide them.
It is guided by 19 so that it can move up and down. A coil 20 made of a shape memory alloy is provided between the guide 19 and the collar 17 of the operating shaft 15, and the upper end and the lower end of the coil 20 are connected by a short-circuit wire 21. Further, since the upper part of the operation shaft 15 penetrates through the opening 22 of the metal closed container 1 and extends upward, the airtightness is maintained by the cover 23 and the O ring 24 formed of a non-magnetic material (for example, aluminum), and the metal closed container is closed. 1
It prevents the insulating gas sealed inside from leaking. A coil 25 is wound around the outside of the cover 23, and the coil 25 is connected to an AC power supply 26. The coil 20 is formed of a shape memory alloy such as a nickel-titanium alloy, and the reverse transformation temperature of this shape memory alloy (the temperature at which the shape memory alloy returns to its original state) is determined when the gas insulated switchgear is in operation. Set higher than the insulating gas temperature of. In addition, the coil 20 has the original shape (shape of the mother phase) as the shape when the temperature rises and extends.

Next, the operation of the disconnecting device 14 of the gas insulated switchgear configured as above will be described. First, instrument transformer
When disconnecting 10 from the main circuit, when coil ₁ has a V ₁ effective value and W is an angular frequency, When a sinusoidal wave is applied, a magnetic flux φ = Φ sin wt is generated in the coil 25. This magnetic flux is generated by the non-magnetic cover 23
Enter 15. Assuming that there is no leakage flux, the voltage induced in the shape memory alloy coil 20 is the number of turns N _{1 of the} coil 25,
If the number of turns of the coil 20 is N ₂ , However, N = N ₁ · N ₂ . If the impedance of the coil 20 is Z, Current flows through the coil 20.

This current causes the coil 20 to generate heat, and when the temperature exceeds the reverse transformation temperature of the shape memory alloy, the coil 20 expands in opposition to the elastic force of the connecting conductor 13 in an attempt to return to the original state, and lifts the operating shaft 15.
When the operating shaft 15 is lifted, the end portion of the connecting conductor 13 is separated from the conductor 3 and disconnected as shown by the alternate long and short dash line in FIG. Next, when the voltage V ₁ applied to the coil 25 is turned off, the temperature of the coil 25 decreases and the coil 20 contracts when the temperature is below the reverse transformation point, so that the operating shaft 15 is pulled downward by the elastic force of the connecting conductor 13. , The end of the connecting conductor 13 contacts the conductor 3. That is, the coil 20 is deformed at low temperature by the elastic force of the connecting conductor 13 (the shape memory alloy is mechanically strong and has a low yield stress at low temperature).

Since the current flowing through the coil 20 can be adjusted by changing the number of turns N, there is no fear of overheating. Further, when the instrument transformer 10 is always connected to the main circuit, the operating shaft 15 is insulated from the main circuit by the shaft portion 16 formed of an insulating material, which is safe.

[Effect of the Invention] As described above, the present invention can eliminate the work of removing the instrument transformer, filling the insulating gas, reassembling, etc., which is required to be disconnected from the main circuit during the withstanding voltage test. ,
The construction period can be greatly shortened, and it is extremely effective especially during a withstanding voltage test in the field.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
FIG. 3 is an enlarged sectional view of a main part of the figure, and FIG. 3 is a sectional view of a conventional gas-insulated switchgear. 1 …… Metal closed container 3 …… Conductor 10 …… Instrument transformer 13 …… Connecting conductor 14 …… Disconnecting device 15 …… Operating shaft 20,25 …… Coil

Claims (1)

(57) [Claims] 1. A disconnecting device for a gas insulated switchgear in which a transformer for an instrument for disconnecting from a main circuit during a withstanding voltage test is housed inside a metal airtight container in which an insulating gas is sealed and which is formed of an elastic material, A connection conductor, one end of which is electrically connected to the primary terminal of the instrument transformer and the other end of which is in contact with the main circuit, and the other end of the connection conductor is opposite to the surface in contact with the main circuit. An operation shaft having one end insulated and connected, a bidirectional memory element which is formed of a shape memory alloy material and operates the operation shaft when heat is generated to bring the connection conductor and the main circuit into non-contact with each other, and the bidirectional memory element. Disconnecting device for a gas insulated switchgear, comprising: a magnetic memory element, and a coil for generating heat by an electromagnetic induction action during a withstand voltage test.