JPS6036969Y2 - gas insulated electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas insulated electrical device, and more particularly to a gas insulated electrical device that can prevent side flash shorts occurring in an insulating spacer installed between metal case joints.

In a switchgear insulated with SF6 gas, it is common to electrically insulate between metal cases at arbitrary lengths and to ground the metal cases for each insulation section.

FIG. 1 shows a conventional method using a bus bar as an example.

As shown in FIG. 1, the bus bar 2 is supported by an insulating spacer 3, and by sandwiching the insulating spacer 3 between the joints of the metal case 1 and filling SF6 gas 5 in the metal case 1, a gas insulated bus bar is constructed. has been done.

The metal cases 1 are each insulated by an insulating spacer 3, and each metal case is grounded by a ground wire 4 to be at ground potential, making it a safe device.

By grounding the metal case 1 in this way, the normal bus bar 2
The metal case 1 is kept at the ground voltage when the commercial frequency current flows through the bus, but the situation changes completely when a switching surge due to system operation or a lightning surge enters the bus bar 2.

In other words, the frequency components of switching surges and lightning surges are several MHz.
Because the inductance of the grounding wire 4 is so high that it cannot be ignored, the metal case 1 is not grounded due to the dt force, and in the case of high frequency voltage, the insulating spacer between the metal cases 1 3, total reflection occurs and this reflection is repeated, causing the metal case 1
The potential of the insulating spacer 3 increases, resulting in a lack of safety, and in some cases, there may be problems such as a flashover occurring on the side surface of the insulating spacer 3 and deteriorating the insulator.

The present invention was made with the aim of eliminating these problems and providing a gas insulated device that is safe and highly reliable.

The present invention eliminates the above-mentioned problems, and as a means for eliminating them, (1) an overvoltage protection device is installed in the insulating section of each metal case to suppress the voltage rise between each insulating section;

(2) An overvoltage protection device is installed in parallel with the insulator in order to prevent side flashing of the insulator due to high frequency and high voltage generated in each metal case insulator.

FIG. 2 shows an embodiment of the present invention.

That is, one end of each metal case 1 is grounded by a grounding wire 4, and a second overvoltage protection device 7 is inserted between the other end and the ground.

Further, it is constructed by inserting a first overvoltage protection device 6 in parallel with an insulating spacer 3 which is an insulator.

According to the present invention, the voltage generated in the metal case 1 is suppressed from rising by the overvoltage protection device 7, and the potential rise of the metal case 1 is suppressed.

Further, since the potential difference between the metal cases 1 is suppressed by the overvoltage protection device 6, side flashing of the insulating spacer 3 can be prevented.

The overvoltage protection devices 6 and 7 may be either lightning arresters or non-linear resistors mainly made of metal oxide.

In addition, the overvoltage protection devices 6 and 7 are configured such that their operating voltages are within the range of overvoltage protection device 7≦overvoltage protection device 6, so that the metal case 1
It is possible to suppress the potential of the insulating spacer 3 and prevent side flashing of the insulating spacer 3.

According to the present invention, as mentioned above, it is possible to prevent the potential rise of the metal case and the side flash of the insulating spacer, and it is possible to provide a gas-insulated electrical device with excellent safety and high reliability. There is something big.

FIG. 3 shows another embodiment of the present invention.

That is, compared to the configuration shown in FIG. 2, the overvoltage protection device 6 is replaced with two overvoltage protection devices 8a and 8b connected in series, one end of the overvoltage protection device 9 is connected to the connection point of the overvoltage protection device 8at8b, and the other end is connected to the ground. is connected to.

Although not shown, even if the overvoltage protection device 9 in FIG. 3 is short-circuited, the same effect as in FIG. 2 can be obtained.

That is, for example, overvoltage protection device 7:overvoltage protection device 6=
When the ratio is 1:2, the potential difference between each metal case 1 can be reduced with the first main purpose being to absorb the high frequency voltage generated in the metal case 1.

Even so, when the potential difference between the metal cases 1 becomes large, the insulating spacer 3 may be bypassed by the overvoltage protection device 6.

In FIG. 2, the overvoltage protection device 6 is replaced by the overvoltage protection device 7.
will be used in series.

On the other hand, in the case of FIG. 3, by setting the overvoltage protection device 9 to zero, the circuit can be made the same as the circuit of FIG. 2, so that the number of overvoltage protection devices can be reduced to half.

In addition, due to high-frequency voltage, a potential difference occurs on the circumference of the metal case, so it is necessary to arrange multiple protection circuits in parallel around the metal tank, as shown in Figures 2 and 3, to protect against overvoltage at each point. Reducing the number of devices is economically extremely important.

It is said that in order to protect the metal case from potential increases caused by such high-frequency voltages, it is sufficient to insert an impedance between the ground, the metal case, or between the insulators. When used, the absolute value of the high frequency voltage will decrease, but side flashing of the insulator between the metal cases may occur.

(2) When an impedance is inserted between the insulators between the metal cases, the vibration frequency is reduced, but there are problems such as an increase in the metal case potential cannot be prevented.

The present invention can technically solve the above problems, and has great effects such as reducing the number of devices used.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a conventional configuration, FIG. 2 is a schematic diagram showing an embodiment of the present invention, and FIG. 3 is a schematic diagram of another embodiment of the present invention. 1...Metal case, 2...Bus bar, 3.
・Curved edge spacer, 4... Earth wire, 5...
...SF6 gas, 6°7, 8.9... Overvoltage protection device.

Claims (2)

[Scope of utility model registration request] (1) In a gas-insulated electrical device in which metal cases are connected and insulated into sections via insulators, and grounded at one point for each insulation section, a lightning arrester or a non-linear resistor is used between the metal cases that sandwich the insulators. A gas-insulated electrical device that is connected through a first overvoltage protection device made of a metal case, and grounded between the ground and a metal case via a second overvoltage protection device made of a lightning arrester or a nonlinear resistor. (2) The gas-insulated electrical device according to claim 1, which is a utility model, and includes a plurality of first overvoltage protection devices in the circumferential direction of the metal case.