JPS6350813Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a gas insulated neutral point grounding resistance device.

Conventionally, this type of equipment has a unit in which resistors are housed in metal containers according to the resistance value and voltage class, and is mounted on an insulator, with one end of the resistor connected to the neutral point of the transformer, and the other One end was connected to a grounding wire, and air was used as insulation for the resistor and as a cooling medium.

However, with this configuration, if the ground potential at the neutral point rises, the metal container becomes high voltage, requiring a protective fence around it, and the air insulation makes this type of device bulky. There was an inconvenience that it was impossible to avoid. Furthermore, since the resistor comes into contact with the outside air, deterioration of the resistor becomes a problem in places with a poor atmosphere.

As a countermeasure to this, the resistor should be stored in a sealed container.
It is conceivable to install it in an insulating gas atmosphere such as SF ₆ . However, if, for example, a single line ground fault occurs on a three-phase line to which this type of device is connected,
A ground fault current flows through the resistor, and as the temperature of the resistor increases, the temperature of the surrounding atmosphere, that is, the insulating gas, rises rapidly. Heat accumulates in the atmosphere for a long time, which has a negative effect on the insulating gas, etc., and if ground faults occur frequently, the temperature of the resistor and its atmosphere will further rise, causing the insulating gas to decompose. There are disadvantages such as generation of corrosive gas. Furthermore, in order to prevent this, there is the disadvantage that the resistor element forming the resistor itself must be increased in size in order to reduce the heat generation of the resistor.

Therefore, the purpose of this invention is to provide a neutral point grounding resistance device that can suppress the rapid temperature rise of the resistance element and insulating gas without increasing the size of the resistance element, and can cool the resistance element in a short time. It is to be.

An embodiment of this invention is shown in the drawings. That is,
This gas insulated neutral point grounding resistance device is a sealed container 1
A resistor 2 is placed insulated in the space of the sealed container 1.
Insulating gas 3 such as SF ₆ , CO ₂ , N ₂ or the like is sealed, and a coolant spraying device 4 is provided at the top, and a socket 6 for a recovery pump device 5 is provided at the bottom. The resistor 2 has a stack of a plurality of flat resistance plates punched in a zigzag shape, two fibrous insulating sheets having heat insulation properties are interposed between these resistance plates, and an insulating layer is placed between the insulating sheets. An insulating plate with high yield strength is interposed. Electrically, each resistance plate is connected in series. This resistor 2 has a lower metal fitting 8 placed on an insulating support 7 such as a support insulator installed at the inner bottom of a sealed container 1, and is stacked on top of it. connected. Further, an upper metal fitting is stacked on the upper surface of the resistor 2 and electrically connected to the uppermost resistance plate, and the resistor 2 is compressed and tightened in the stacking direction by appropriate pressing means (not shown). In the figure, 9 is a low voltage side terminal, 10 is a high voltage side terminal, and 11 is an electric field relaxation shield that covers the high voltage section.

In addition, the dispersion device 4 has a refrigerant tank 12 installed at the top of the sealed container 1, and a valve 1 at the bottom of the refrigerant tank 12.
A dispersion device 14 is provided through the resistor 3, and the dispersion device 14 is arranged just above the resistor 2. A coolant 15 having a relatively high boiling point, such as fluorocarbon, is injected into the coolant tank 12 . The valve 13 is opened by the following means. That is, the valve is a solenoid valve, the ground fault current flowing through the resistor 2 is detected by a neutral point current transformer, the signal of the ground fault current is transmitted to the solenoid valve, and the valve is opened. Further, the valve 13 may be operated by a temperature sensor when the temperature of the resistor 2 or the insulating gas exceeds a specified value. In this case, the valve itself may be made of bimetal. Further, the valve 13 may be operated by a pressure sensor when the pressure increase value of the insulating gas 3 due to temperature rise exceeds a specified value. In this case, the valve itself may be configured to open upon receiving pressure.

The pump device 5 includes a socket 6 provided at the bottom of the sealed container 1, a suction pipe 17 of the pump 16 connected to the socket 6, a discharge pipe 18 connected to the refrigerant tank 12, and a coolant 15 supplied to the socket 6. When the coolant accumulates, the pump 16 is activated manually or automatically using a float switch or the like to collect the coolant into the refrigerant tank 12.

Now, when a one-wire ground fault occurs in the system and a large current flows through the resistor 2 for several seconds, the resistor 2 generates heat, and almost at the same time, the valve 13 of the spraying device 4 opens. For this purpose, the cooling liquid is sprayed onto the resistor 2 from the sprayer 14 through the valve 13 as shown in the figure, and the sprayed liquid is heated by the heat of the resistor 2, absorbs latent heat of vaporization, and vaporizes. In this way, the rise in temperature of the resistor 2 and the rise in the temperature of the insulating gas 3 is suppressed, thereby preventing decomposition of the insulating gas and suppressing the generation of corrosive gas. When the resistor 2 stops generating heat and is naturally cooled, the vaporized cooling gas in the sealed container 1 solidifies and accumulates in the socket 6 at the bottom. Then, the pump 16 is operated to collect the refrigerant into the refrigerant tank 12.

With this configuration, this type of device with excellent cooling characteristics can be made small, lightweight, and inexpensive, and since the temperature rise of the sealed container 1 is small, the paint on the outer wall will not be damaged or people will not get burned if they touch it. Furthermore, since the cooling is performed by spraying the cooling liquid 15, the heat radiation time constant is small, that is, the cooling time is shortened, and even if ground faults occur frequently, there is no heat accumulation and reliability can be improved.

Note that the heat insulating effect of the insulating sheet of the resistor 2 and the provision of a heat absorbing material between the resistors serve to suppress the rapid temperature and pressure rise of the insulating gas 3; Since the cooling time is long, the temperature rise may accumulate and the temperature rise value of the resistor 2 and the sealed container 1 may become excessive. For example, if the rated current is applied for the rated time, resistor 2 will have a resistance of approximately 50% even after one day (24 hours) has passed.
℃, and it has been confirmed that a temperature rise of approximately 10℃ remains in sealed container 1. Therefore, if only these are used, the cooling capacity will not be able to keep up with the occurrence of frequent ground faults. However, according to this invention, it is possible to sufficiently cope with such high-frequency ground faults. It goes without saying that this invention can also be effectively applied to resistance devices that do not use heat insulating materials or heat absorbing materials.

As described above, the gas insulated neutral point grounding resistance device of this invention has the following effects because the insulating gas is sealed in the sealed container containing the resistor and the coolant spraying device is provided at the top. (1) Since the resistor is insulated and placed in a sealed container filled with insulating gas, the live parts are hidden, eliminating the risk of electric shock and eliminating the need for a protective fence, which can significantly reduce the installation space. .

(2) Since the resistor is isolated from the outside air, there is no need to worry about deterioration even in places with a bad atmosphere and no maintenance is required.

(3) Transportation and installation are simplified because the entire device is constructed as one unit in a sealed container.

(4) Since the resistor is cooled by being sprayed with a cooling liquid, a sudden rise in the temperature of the resistor can be suppressed, and the sealed container can be made smaller and lighter, and it can be made cheaper. Therefore, the temperature rise in the sealed container is reduced, and damage to the exterior wall coating and risk of burns can be prevented.

(5) Since cooling can be achieved in a short time, it can withstand frequent ground faults and is highly reliable.

[Brief explanation of the drawing]

The drawing is a sectional view of one embodiment of this invention. 1... Sealed container, 2... Resistor, 3... Insulating gas, 4... Dispersion device, 5... Pump device.

Claims (1)

[Scope of utility model registration request] a sealed container at earth potential, a resistor disposed within the sealed container at an insulating distance from the sealed container, an insulating gas sealed in the sealed container, and a resistor installed at the top of the sealed container. a spraying device that sprays a coolant onto the resistor when the resistor generates heat, and a pump device that has a socket for the coolant at the bottom of the sealed container and collects the coolant to the spray device. Gas insulated neutral point earthing resistance device.