JPH02294215A - Power cable line - Google Patents

Abstract

PURPOSE:To reduce the receiving space for each cable circuit by laying a power cable in the central phase of a three-phase power cable line in vertical snakes in equilateral triangular arrangements and each of two power cables in the lower phase with their snake phases deviated at 180 deg.. CONSTITUTION:Among the power cables 5A to 5C laid in vertical snakes where their axial cross sections are arranged in equilateral triangular arrangements at the verteces of snakes, a power cable 5A in the central phase and two power cables 5B and 5C in the lower phase are laid with their snake phases deviated at 180 deg.. That is to say, a power cable 5A in the central phase and two power cables 5B and 5C in lower phase are axially continuously laid so that the width and pitch may be the same, but the vertex and base points may be opposite. In this laying since the bending points of the snakes will be lined up at the same position, the three-phase cables can collectively be fixed with a cleat 7 at this position. The receiving space for cable 5A to 5C circuits can thereby be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power cable line in which vertical snakes are laid in an equilateral triangular arrangement over a long distance, for example in a tunnel.

[Prior Art] Power cables with a voltage of 154 KV or higher are often laid long distances in underground tunnels, with three cables forming one circuit.

The cross-sectional arrangement of the three strips is often an equilateral triangular arrangement to avoid impedance imbalance, but in long-distance lines, it is not necessary to have a uniform equilateral triangular arrangement throughout the line by twisting each connection point. .

4 and 5 show conventional examples of power cable lines laid in tunnels. As shown in the figure, a vertical metal fitting 1 is erected in the tunnel, and a receiving metal fitting 2 is supported horizontally on the vertical metal fitting 1.

A disaster prevention trough 3 is supported on the receiving metal fitting 2.

Three-phase power cables 5A, 5B, and 5C are laid on the lower surface support spacer 4 in the disaster prevention trough 3 in an equilateral triangular arrangement. An interphase spacer 6 is interposed between these three-phase power cables 5A, 5B, and 5C to provide separation between the phases. In this way, three-phase power cables 5A, 5B,
The reason why 5C is not arranged closely in an equilateral triangle but separated between the phases is as follows.
This is to reduce eddy current loss in the cable metal sheath during power transmission and to reduce thermal interference between cables. Further, these three-phase power cables 5A, 5B, and 5C are vertically snaked together at a pitch length of 5 to 10 m in order to absorb thermal expansion and contraction.

Note that 7 is a cable cleat. A water cooling pipe 8 is disposed at the upper part of the trough 3.

By the way, it has recently become extremely difficult to construct underground tunnels due to urban roads and underground conditions, and once constructed, it is necessary to lay as many cables as possible within the tunnel. Therefore, the accommodation space for each cable line must be reduced as much as possible.

[Problems to be Solved by the Invention] However, in the conventional power cable line, the three-phase power cables 5A, 5B, and 5C had to be projected high above the cleat 7 to create a vertical snake. There was a problem in that the width W was large and a large amount of space was required for accommodating the cable line.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power cable line that does not require much accommodation space even if it is snaked vertically.

[Means for Solving the Problems] To explain the configuration of the present invention for achieving the above object, the present invention has three phases of a single-core power cable separated from each other and an axial cross section at least at the top of the snake. In a power cable line in which vertical snakes are laid in an equilateral triangular arrangement, one power cable in the center phase and two power cables in the lower phase are laid with their snake phases shifted by 180 degrees. It is characterized by

[Operation] In this way, in a three-phase power cable line laid vertically in an equilateral triangular arrangement at least at the top of the snake, one power cable in the center phase and two in the lower phase each. When power cables are laid with their snake phases shifted by 180 degrees, other power cables can be snaked within the snake width of one power cable.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 and 2 show an embodiment of the present invention. The power cable line of this embodiment is laid in a vertical snake in such a way that the three phases of the single-core power cables 5A, 5B, and 5C are separated from each other, and the axial cross section is in an equilateral triangular arrangement at least at the top of the snake. The points are the same as before. In this embodiment, these power cables 5A, 5B
, 5C, one center phase power cable 5A and two lower phase power cables 5B and 5C are characterized in that they are laid with their snake phases shifted by 180 degrees. That is, the single power cable 5A of the center phase and the two power cables 5B, 5C of the lower phase are arranged in the axial direction so that the snake width and pitch are the same, and the top and bottom points are opposite, as shown in the figure. It has been laid continuously. When laid in this manner, the inflection points of the snakes are lined up at the same position as shown in the figure, so the three phases can be fixed together with the cleat 7 at this position.

In the top and bottom sections of the snake, which are the standard cross sections of the line, the three phases of power cables 5A, 5B, and 5C are separated by a phase-to-phase distance L.
If the snakes are arranged in an equilateral triangular shape, the snake laying width W can be kept within (flXL)/2.

By the way, the sheath distortion, snake width change, and axial force that occur during line power transmission must be kept as small as possible, but these greatly depend on the snake installation width W as shown in FIG. 3.

As shown in the figure, it is desirable that the snake installation width W is larger, but this goes against the idea of saving tunnel space, so in reality W = 1.
．． In many cases, it is approximately 0D (D: cable outer diameter).

When w < 1.0D, the axial force. Sheath distortion becomes an issue and may have negative effects on the cable.

In this example, even if the phase distance (≧2D) is 2D, W=
1.73D can be secured, the axial force, etc. can be greatly suppressed, and the effect of suppressing the total snake laying width by reducing the snake laying width W is also added.

[Effects of the Invention] As explained above, the power cable line of the present invention has one power cable in the center phase and two in the lower phase of a three-phase power cable line laid vertically in an equilateral triangular arrangement. Since the power cables in the strip are laid with their snake phases shifted by 180 degrees, it is possible to snake other power cables within the snake width of one power cable. Therefore, the snake laying width is narrower than in the past, and the snake can be laid vertically without requiring a high space above as in the past, and the snake can be laid by making effective use of the space.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the installation state of the power cable line according to the present invention, Figure 2 is a cross-sectional view at the top of the snake in Figure 1, and Figure 3 is the snake installation width, sheath distortion, and snake width change. , a characteristic diagram showing the relationship with axial force, FIG. 4 is a cross-sectional view of a power cable line laid in a state, and FIG. 5 is a side view of a conventional snake laid state. 1... Vertical hardware, 2... Receiving hardware, 3... Disaster prevention trough, 4... Bottom support spacer, 5A, 5B, 5C...
- Power cable, 6... interphase spacer, 7... cable cleat, 8... water cooling pipe.

Claims (1)

[Claims] In a power cable line in which three phases of a single-core power cable are spaced apart from each other and the axial cross section is arranged in an equilateral triangle at least at the top of the snake, the power cable is laid vertically in a vertical snake manner. A power cable line characterized in that the two power cables of the lower phase and the lower phase are laid with their snake phases shifted by 180 degrees.