JPS6235329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to ground wire current reduction in gas insulated electrical equipment.

A conventional gas insulated switchgear, which is this kind of gas insulated electrical device, is shown in FIG. In the figure, 1 to 5 are sealed metal tanks in which a current-carrying conductor is housed and insulating gas is sealed, and disconnector tank 1, disconnector tank 2, and disconnector tank 3 are electrically The circuit breaker tank 5 and current transformer tank 4 are electrically insulated. These tanks are connected to a main grounding line 10 of a grounding network buried underground through grounding lines 6 to 9.

In such a structure, an induced current is generated in the circuit of circuit breaker tank 5 - grounding wire 9 - main grounding wire 10 - grounding wire 8.
i ₁ , and disconnector tank 1 - bushing tank 2 -
An induced current i2 is generated in the circuit of the disconnector tank 3, the grounding wire 7, the main grounding wire 10, and the grounding wire ₆ due to leakage magnetic flux generated by the energized conductor current. This induced current is large, causing the grounding wire to overheat and melt.
Also, overheating of the ground wire exposed from the ground is a safety hazard. In addition, because an induced current flows through the tank, the temperature of the tank and current-carrying conductor increases.
The tank becomes larger.

The present invention aims to eliminate the above-mentioned drawbacks by reducing the amount of leakage magnetic flux caused by current in a current-carrying conductor that passes through a circuit including a grounding wire, and by increasing the length of the grounding wire of the circuit.

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 2 is a perspective view of one phase of a three-phase separated gas insulated switchgear according to an embodiment of the present invention. FIG. 3 is a perspective view of the three phases. In the figure, the same symbols as in FIG. 1 indicate the same parts, but in the present invention, the mechanically connected disconnector tank 1,
Two main grounding wires 10 and 11 are provided in parallel to a group of tanks such as the bushing tank 2, the disconnector tank 3, the current transformer tank 4, and the circuit breaker tank 5, forming a grounding network. One of the grounding wires 8 is connected to the main grounding wire 11, and the other grounding wire 9 is connected to the main grounding wire 1.
Connected to 0.

With this configuration, when the currents in the current-carrying conductors are flowing in the same direction, the induced current i ₃ is divided into circuit breaker tank 5 - grounding wire 9 - main grounding wire 10 - grounding wire 6 - disconnector tank 1 - bushing It flows through a large circuit consisting of tank 2 - disconnector tank 3 - ground wire 7 - main ground wire 11 - ground wire 8. Therefore, the impedance of the circuit becomes high and induced current can be reduced.

On the other hand, the induced voltage that causes the induced current to flow is generated at a high level in the tank that has the largest mutual inductance with the current-carrying conductor. Therefore, if each ground wire and tank are connected so that the voltage induced in the circuit breaker tank 5 and the voltage induced in the bushing tank 2 and disconnector tanks 1 and 3 are in opposite directions, the induced voltage will be reduced. can be reduced, resulting in less induced current. That is, in FIG. 2, by connecting the grounding wire 7 to the main grounding wire 10 and the grounding wire 6 to the main grounding wire 11, the voltage induced in the circuit breaker tank 5 of the circuit through which the induced current flows, and the voltage induced in the circuit breaker tank 5, The direction of the voltage induced in the bushing tank is different, so the induced voltage in the circuit can be reduced and the induced current can be reduced.

In addition, as shown in FIG. 3, four main grounding wires 10,
11, 12, and 13 in parallel with the tank, and main grounding wires 14 and 15, and connecting the tank's grounding wire to the main grounding wire as shown in Figure 2, a circuit spanning between phases by the grounding wire can be established. This can be done by the main grounding wires 10 to 15, but the impedance of the main grounding wire is high and a large induced current does not flow.

Incidentally, the alpha suffixes in FIG. 3 are added for convenience in order to distinguish each phase.

In addition, a circuit that spans between phases via a tank, for example,
Circuit of grounding wire 8a - breaker tank 5a - grounding wire 9a - main grounding wire 10 - grounding wire 8b - circuit breaker tank 5b - grounding wire 9b - main grounding wire 12 - grounding wire 8c - circuit breaker tank 5c - grounding wire 9c For the induced voltage, the mutual inductance between the breaker tank and the current-carrying conductor is the largest, so a large induced voltage is generated in the breaker tank, but since the three phases are connected in series, the induced voltage is canceled out. The relationship becomes zero. Therefore, there is only an induced voltage from other lines, and the induced current flowing through this circuit is reduced.

FIG. 4 is a perspective view of a three-phase separated gas insulated switchgear according to another embodiment of the present invention. In this embodiment, the arrangement of the main grounding wires of the device shown in FIG. 3 is finely arranged to reduce the grounding resistance and the impedance of the grounding network, thereby reducing potential rise in the event of an accident.

That is, main grounding lines 16 and 17 are provided in parallel with main grounding lines 11 and 13 without being electrically connected. Then, the main grounding wire 11 and the main grounding wire 12 are short-circuited and the grounding wire 18
Similarly, the short-circuit grounding wires 19 to 21 are connected via the short-circuiting grounding wire so that only one phase does not create a short circuit. By doing so, the spacing between the grounding networks can be made finer without increasing the induced current.

FIG. 5 is a partial perspective view of one phase of a three-phase separated gas insulated switchgear according to another embodiment of the present invention. FIG. 6 is a perspective view of three phases. In the figure, the same reference numerals as in other figures indicate the same parts, but in this embodiment, as shown in FIG.
8 wires are installed as shown below, and the tank grounding wire for one phase is 4 wires.
main ground wire (e.g. 10, 11, 16, 22)
In order to avoid short circuits, the multiple grounding wires 6 to 9 of electrically connected tanks are wired so that they are not connected to the same main grounding wire. In other words, when wired as shown in Figure 5, the circuit through which the induced current flows is the circuit breaker tank 5 - grounding wire 9 - main grounding wire 22 - main grounding wire 15 - main grounding wire 10 - grounding wire 6 - disconnector tank 1
- Bushing tank 2 - Disconnector tank 3 - Grounding wire 7 - Main grounding wire 16 - Main grounding wire 14 - Main grounding wire 11
- The grounding wire 8 becomes a long circuit, resulting in high impedance and less induced current.

As described above, according to the present invention, the impedance of a circuit including a grounding wire can be increased, and induced current can be reduced. Therefore, overheating and fusing of the ground wire can be prevented, and overheating of the exposed ground wire can be prevented.
Improves safety. Further, since the induced current flowing through the tank is reduced, the temperature rise of the tank and the current-carrying conductor is small, and miniaturization is possible.

It goes without saying that the present invention can be applied not only to the embodiments but also to gas-insulated busbars.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a conventional gas insulated switchgear, and Figs. 2 and 3 are perspective views showing one phase and three phases of a three-phase separated gas insulated switchgear which is an embodiment of the present invention. 4 are perspective views showing another embodiment of the present invention, and FIGS. 5 and 6 are perspective views showing one phase and three phases of other embodiments of the present invention. In the figure, 1, 1a, 1b, 1c...disconnector tank,
2, 2a, 2b, 2c...butching tank, 3,
3a, 3b, 3c...Disconnector tank, 4, 4a, 4
b, 4c...Current transformer tank, 5, 5a, 5b, 5c
...Breaker tank, 6-9...Ground wire, 10-1
7, 22, 23...Main grounding wire, 18-21...Short-circuit grounding wire, _i1 - _i4 ...Induced current.

Claims (1)

[Claims] 1. In gas-insulated electrical equipment connected to a grounding network in which a tank containing a current-carrying conductor is buried along with an insulating gas, one of the main grounding wires of at least two main grounding wires constituting the above-mentioned grounding network shall be Connect one of the grounding points of the tank with the first grounding wire,
A gas insulated electrical device characterized in that the other main grounding wire and the other grounding point of the tank are connected by a second grounding wire.