JP2000245022A - Gas insulated electrical equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce an induced current flowing in a buried ground line and to increase the current capacity of a gas-insulated electric device. SOLUTION: In a gas insulated electric device in which a large number of metal cases 3, 4, 6, 7 in which gas insulated equipment is housed are connected and arranged, a phase contact buried for each phase on a site where the metal case is installed. A ground wire 11a, an interphase ground wire 11 connected at both ends of the phase ground wire and buried in the site
At least one or more metal cases 7 provided for each phase are connected to the inter-phase ground line 11 via a ground line 10a, and the remaining metal cases are connected via the ground line 10 Is connected to the phase ground line 11a of the corresponding phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-insulated electric device, and more particularly to a gas-insulated electric device in which a ground wire is optimally arranged to reduce a ground current.

[0002]

2. Description of the Related Art A gas-insulated electric device is constructed by housing various kinds of gas-insulated equipment in a metal case filled with an insulating gas and grounding the metal case. In recent years, with an increase in power demand, higher voltage and larger current capacity have been developed. When a large current flows through the main circuit, a large magnetic field is generated, and an induced current is generated in the metal case.

FIG. 5 is a diagram for explaining the principle of generation of the induced current.

In FIG. 1, reference numeral 2 denotes a metal case in which gas-insulated equipment is housed. Main circuit 1 in metal case 2
When the current I flows through the metal case 2, a magnetic field Φ is generated, and the metal case 2 is connected to the ground line 11 by the rising ground line 10, so that the metal case 2 is surrounded by the metal case 2, the rising ground line 10, and the ground line 11. A voltage is induced in the loop by the magnetic field Φ, and this voltage causes an induced current i to flow through the loop.

In general, there are a multi-point grounding method and a single-point grounding method as a grounding method of a gas-insulated electric device. On the other hand, a single point is grounded, and the multipoint grounding method is a method in which each insulating device in the gas insulated electric device is individually grounded. In recent years, to reduce jacket surges that occur when disconnecting switches and grounding switches,
The number of cases where the multipoint grounding method is adopted is increasing.

FIG. 6 is a diagram showing an example of a conventional multi-point grounding type gas insulated electric device.

In the figure, 3 is a circuit breaker, 4 is a circuit breaker branch, 6 is a disconnector and a ground switch, 7 is a lower bushing tank, 10 is a circuit breaker 3, a circuit breaker branch 4, a disconnector and a ground. Metal case of equipment such as switch 6 and each phase grounding wire 1 described later
A grounding wire connecting between 1a, 11 is an interphase grounding wire buried underground around the gas insulated electric device, 11a is buried underground substantially parallel to the gas insulated electric device of each phase, and at both ends. A phase ground line 12 connected to the ground line 11 is a bus line of the gas insulated electric device of each phase.

As shown in FIG. 1, a metal case of a device arranged for each phase is connected to a phase ground line 11a of each phase by a rising ground line 10, and an induced current flowing through the rising ground line 10 is provided. Is configured to flow into the phase ground line 11a and further flow from the phase ground line 11a to the inter-phase ground line 11.

In such a multi-point grounded gas insulated electric device, a large induced current i flows through the rising ground line 10 as described in the principle of generation of induced current. In particular, in a large current type in which the current I flowing through the main circuit 1 is large, the induced current i flowing through the rising ground line 10 becomes large, and the conductor such as the rising ground line 10 and the conductor There is a possibility that cracks will occur in the concrete due to the difference in the thermal expansion coefficient between the concrete in which the concrete is embedded. Conventionally, when the induced current flowing through the grounding wire becomes large, measures such as increasing the size of the grounding wire or increasing the number of grounding wires to reduce the current density of the current flowing through the grounding wire to a reference value or less. I was

[0010]

However, in a conventional gas insulated electric device of a multipoint grounding system, it is necessary to reduce the induced current flowing through the grounding line by increasing the size of the grounding line or increasing the number of grounding lines. However, in order to reduce the induced current, the arrangement of the rising ground line and the ground line has not been sufficiently considered.

[0011] An object of the present invention is to solve the above-mentioned problems by appropriately arranging a rising ground line and a ground line to reduce the induced current flowing through the rising ground line and the ground line. It is to provide an insulated electric device.

[0012]

The present invention employs the following means in order to solve the above-mentioned problems.

In a gas insulated electric device in which a number of metal cases accommodating gas insulated equipment are connected and arranged, a phase ground wire buried for each phase on a site where the metal case is installed; An interphase ground wire connected at both ends of the wire and buried in the site, and at least one or more metal cases provided for each phase are set up and connected to the interphase ground wire via the ground wire, The remaining metal case is set up and connected to the phase ground line of each corresponding phase via a ground line.

In a gas insulated electric device in which a number of metal cases accommodating gas insulated equipment are connected and arranged,
A phase ground wire buried for each phase on the site where the metal case is installed, and an interphase ground wire connected at both ends of the phase ground wire and buried on the site, The provided metal case is connected to the phase ground line of each corresponding phase via a rising ground line, and at least one or more phase ground lines are connected between buses on which the metal case of each phase is arranged. Are arranged within a range of a distance of about 1/4 of the distance between the buses from the center of the line.

Further, in a gas insulated electric device in which a number of metal cases accommodating gas insulated equipment are connected and arranged,
A phase ground line embedded in each site on the site where the metal case is installed, and one ground line connecting the phase ground lines embedded in the site where the metal case is installed,
A metal case which is electrically insulated from each other is set up and connected to the phase ground line of each corresponding phase via a ground line.

Further, in the gas insulated electric device according to the third aspect, the ground wire is connected between substantially central portions of the phase ground wires.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a diagram showing the overall configuration of a gas-insulated electric device employing a multipoint grounding system according to this embodiment.

In FIG. 1, reference numeral 10a denotes a rising ground line for connecting between a metal case such as a bushing lower tank 7 located at both ends of the gas insulated electric device arranged for each phase and the ground line 11. The other configuration is the same as the configuration of the same reference numeral shown in FIG.

The present embodiment differs from the prior art shown in FIG. 6 in that the rising ground line 10a is connected to the ground line 11 without connecting to the phase ground line 11a. With this configuration, an induced current generated in a loop formed through the metal case to which the rising ground line 10a is connected flows through the rising ground line 10a,
The induced current generated in the gas insulated electric device having the other phase relationship with the metal case flows in and out through the ground line 11. Therefore, the two induced currents are superimposed and flow on the rising ground line 10a. However, since there is a phase difference between the induced currents, the induced currents are offset each other and the induced currents can be reduced as a whole. it can. As a result, the rise in the temperature of the rising ground wire 10a of the bushing lower tank 7 can be kept low, and cracking of concrete can be prevented.

In this embodiment, the case where the bushing lower tank 7 is disposed at both ends of the gas insulated electric device of each phase has been described. However, in the case where equipment other than the bushing lower tank is disposed, It is preferable to connect a rising ground line 10 a between the metal case of the device and the ground line 11.

Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 2 is a diagram showing the overall configuration of a gas-insulated electric device employing a multipoint grounding system according to this embodiment.

As shown in FIG. 1, at least one or more phase grounding wires 11a are provided at substantially the center between the bus lines 12 where the gas insulated electric devices of the respective phases are arranged, or between the center and the bus lines 12. It is arranged within a range of about 1/4 of the distance. The other configuration is the same as the configuration of the same reference numeral shown in FIG.

In this embodiment, the prior art shown in FIG. 6 is different from the prior art shown in FIG. 6 in that each phase ground line 11a is installed near the bus line 12, and the magnetic flux from the main circuit crossing the loop formed by the ground line 11a. The phase ground wire 11a is connected to the bus 1
The difference is that the induced current is reduced by arranging in a substantially central portion or the like between the two.

FIG. 3 shows that the phase ground line 11a is connected to the bus line 12
It is a figure for explaining the principle of reduction of induced current by arranging in the approximate center part between.

In the figure, 1 is a main circuit of each device of the gas insulated electric device arranged on the bus line 12, 2 is a cross section of a metal case of the device, and 111 to 117 are phases arranged in parallel with the bus line 12. The cross section of the ground line, 118, is arranged in a direction perpendicular to the
7 is a ground line. The broken line indicates the magnetic flux Φ induced by the main circuit current flowing from the back side of the paper of the main circuit 1 to the front side.

FIG. 3A shows a case where the phase grounding lines 111 and 113 are arranged on both sides of the phase grounding line 112 disposed immediately below the main circuit 1. In this case, the magnetic flux .PHI. Since the magnetic flux Φ links the loops formed in the ground lines 111 and 112 and the ground line 118, and the loops formed in the phase ground lines 112 and 113 and the ground line 118, an induced current is induced in each loop. Will be.

On the other hand, in FIG. 3B, phase ground wires 115 and 116 are arranged at positions separated from immediately below the main circuit 1, for example, at the center between the main circuits 1 of each phase. This is the case where the phase ground lines 114 and 117 are arranged on both sides thereof. In this case, the phase ground lines 115 and 116 and the ground line 11 are arranged.
Since the magnetic flux interlinking with the loop formed by the loop 8 can be reduced as a whole, the induced current flowing through this loop can be reduced.

Based on the principle of reducing the induced current, the multipoint grounding type gas insulated electric device of the present embodiment has a substantially central portion of the bus line 12 of each phase forming the main circuit, or a central portion thereof. The phase ground line 11a is arranged within a range of about 1/4 of the distance between the section and the bus line 12. Ideally, no induced current is induced in each phase ground line 11a by the magnetic flux induced in the gas-insulated electric device arranged along the bus line 12 by such a configuration.

In this embodiment, the induction current can be effectively reduced by arranging the phase ground line 11a ideally at the center of the bus line 12 of each phase. Even if it is not always possible to arrange the components in the central portion due to the arrangement of the constituent devices, for example, even if they are arranged within a range displaced from the central portion by about 1/4 of the distance between the bus lines 12 of each phase. In addition, the effect of reducing the induced current can be obtained.

According to this embodiment, the induced current can be reduced by about 10 to 20% as compared with the conventional one.

Also, by combining this embodiment with the first embodiment, the effects of both can be synergistic.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a diagram showing the overall configuration of a gas-insulated electric device employing a multipoint grounding system according to this embodiment.

In the figure, reference numeral 5 denotes a current transformer for an instrument, 11b
Is a phase ground line 1 at substantially the center of the phase ground line 11a of each phase.
This is a ground line connecting between the terminals 1a.

The embodiment shown in FIG. 4 is different from the prior art shown in FIG. 6 in that a ground wire 11b is provided and the metal case of the equipment constituting the gas insulated electric device of each phase is connected to each other. Each of the metal cases that are electrically insulated is connected to the phase ground line 11a via the rising ground line 10 and is provided around the gas insulated electric device provided in the prior art shown in FIG. The difference is that the buried interphase ground line 11 is not provided.

As described above, according to the present embodiment, the inter-phase ground wire 11 provided around the site of the gas-insulated electric device in the prior art is eliminated, and the phase ground wire 11a of each phase is substantially omitted. Since one ground line 11b is provided at the center, no loop is formed in the ground lines 11a and 11b, and the generation of induced current in the ground lines 11a and 11b can be prevented. In addition, the length of the whole grounding wire can be made shorter than that of the prior art, and the cost of installing the grounding wire can be reduced.

In the present embodiment, the ground wire 11b is configured to connect between the substantially central portions of the phase ground wires 11a of each phase. However, the ground wire 11b is not necessarily substantially formed due to the arrangement of the equipment constituting the gas insulated electric device. The same effect can be obtained without connecting the central portions.

[0040]

According to the present invention, it is possible to reduce the induced current flowing through the ground line by optimizing the arrangement or connection of the ground line, and to increase the size of the ground line as in the prior art. It is possible to provide a gas-insulated electric device having a large current capacity without increasing the number or the number thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a gas-insulated electric device employing a multipoint grounding system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a gas-insulated electric device employing a multipoint grounding method according to a second embodiment of the present invention.

FIG. 3 is a diagram for explaining the principle of reducing induced current by arranging a phase ground line 11a in a substantially central portion between bus lines 12 in the second embodiment.

FIG. 4 is a diagram showing an overall configuration of a gas-insulated electric device employing a multipoint grounding system according to a third embodiment of the present invention.

FIG. 5 is a diagram for explaining the principle of generation of an induced current.

FIG. 6 is a diagram showing the overall configuration of a gas-insulated electric device employing a multipoint grounding method according to the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main circuit 2 Metal case 3 Circuit breaker 4 Circuit breaker branch pipe 5 Current transformer for instrument 6 Disconnector and ground switch 7 Bushing lower tank 10, 10a Start-up ground line 11 Interphase ground line 11a Phase ground line 11b Ground line

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Manabu Takamoto 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture F-term in Kokubu Plant, Hitachi, Ltd. 5G017 BB03 JJ02

Claims (4)

[Claims] 1. A gas-insulated electrical device in which a number of metal cases accommodating gas-insulated equipment are connected and arranged, wherein a phase ground wire buried for each phase on a site where the metal case is installed; An inter-phase ground wire connected at both ends of the ground wire and buried in the site, at least one metal case provided for each phase is started up and connected to the inter-phase ground wire via the ground wire. A gas insulated electric device wherein the remaining metal case is set up and connected to the phase ground line of each corresponding phase via a ground line. 2. A gas insulated electric device in which a number of metal cases accommodating gas insulated equipment are connected and arranged inside, wherein a phase ground wire buried for each phase on a site where the metal case is installed; An inter-phase ground wire connected at both ends of the ground wire and buried in the premises, a metal case provided for each phase is set up and the phase ground wire of the corresponding phase is set up via the ground wire. And connecting at least one or more of the phase grounding wires within a range of approximately 1/4 of the distance between the buses from the center between the buses where the metal cases of each phase are arranged. And gas insulated electrical equipment. 3. A gas-insulated electric device in which a number of metal cases accommodating gas-insulated equipment are connected and arranged, wherein a phase ground wire buried for each phase on a site where the metal case is installed; A ground wire buried on the site where the case is installed and connecting between the phase ground wires;
A gas insulated electric device, wherein metal cases that are electrically insulated from each other are set up and connected to the phase ground wires of the respective phases via ground wires. 4. The gas insulated electric device according to claim 3, wherein the ground wire is connected between substantially central portions of the phase ground wires.