JPS5943888B2 - Cable installation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plurality of consecutive manhole sections (here, one manhole section refers to a section sandwiched between adjacent manholes connected by a cable conduit).

) relates to a cable laying method in which an electric cable having a length greater than the sum of the lengths of these manhole sections is laid throughout the entire section.

Generally, when a long electric cable is laid all at once in a series of manhole sections, such as I and II, as shown in Figure 1, the long wire 1 is passed through the conduits of all the manhole sections. Thereafter, the tip is attached to the cable end 2 to be laid, and this wire is wound up with a winch 3.

In order to lead the wire 1 through the conduit, it is necessary to insert a call line into each manhole section and feed the wire tip into the adjacent manhole in sequence.

However, this type of wire has poor slippage within the cable conduit (the longer the length of the wire is, the greater the pulling force is required).

Such retracting work often takes a long time.

Furthermore, if the total length of the section to be pulled in at once is long, the cable being pulled in will be subjected to a large tension due to its own weight and the frictional force with the cable conduit, which is undesirable as it may lead to accidents such as breakage of the cable core wire.

The present invention has been made with attention to the above points, and an object of the present invention is to provide a method for laying a long electric cable into a conduit while passing through one or more manholes.

A further object of the present invention is to provide a method of laying cables that have low tensile strength by the above-mentioned means.

A basic embodiment of the cable installation method of the present invention will be explained with reference to FIG.

In FIG. 2, the cable 5 wound around the cable drum 4 is shown in cross section in the manhole section (■).

The length is greater than the sum of the lengths of each section of ■ and ■, and the manhole 61 remanhole 7. 8 and up to the manhole 9, the following method is used.

First, in each manhole section I, n, and III, a take-up loaf "1" of a length corresponding to the length of that manhole section is placed.
Insert 0,11.12.

This work can be done at the same time or at different times.

Next, all sections of the take-up ropes 10, 11, and 12 are connected in cascade, respectively, to form a series of take-up rope groups.

Then, one end 13 of the group of take-up ropes is connected to one end of the cable 5, the other end 14 is connected to the winch 15, and the group of take-up ropes is sequentially wound to pass through the entire sections I, n, and III of the cable 5. Complete the installation.

According to the above method, the wire can be pulled in separately for each section instead of the conventional work of pulling in long wires one after another, so the work efficiency is high and the pulling force for each section is small.

FIG. 3 is a cross-sectional view of the rope when the rope 16 is coated with a plastic coating 17 to reduce the frictional resistance between the rope and the inner surface of the pipe when the entire length of the take-up rope group is long.

In carrying out the present invention, if the material and outer diameter of the rope sheathing are made to have characteristics similar to those of the cable to be drawn in, the fifth
When the cable feeding device 18 is installed in a manhole through which the cable passes as shown in the figure, it is easy to set the feeding speed and gripping force, and the work efficiency is extremely high due to the directrix.

In other words, when the winch wire is used as the pulling rope as in the past, the feeding conditions of the intermediate feeding device are significantly different between the rope and the cable, so during the installation work the pulling device is moored and the setting conditions of the feeding device are changed. Although this was necessary, the method of the present invention can omit this work.

Fig. 4 is an example of an endless belt type feeding device that feeds the cable in the direction of arrow 19, which is suitable for the embodiment shown in Fig. 5, and 20 indicates that when the cable to be fed out has slack, the amount of slack is detected and the feed speed is adjusted accordingly. This is a sag detection device that provides feedback.

This feeding device 18 is maintained at a feeding speed according to the state of the slack detection device so that slack is generated in the cable 22 on the sending side when the cape 21 is sent out for static elimination.

This can be done by adding the output of the sag detector to the feed rate controller.

FIG. 5 shows an example in which cable laying work was carried out according to the method of the present invention using the apparatus shown in FIG. When the device 18 is installed and its gripping force is set to be optimal when gripping a cable.

Next, when the winch 24 is driven, the rope 27 is first pulled off and the slack at the connection between the ropes 26 and 27 is reduced.

At this time, the slack detection device of the cable feeding device 18 is activated, and when the slack becomes below a certain value, the feeding device starts feeding.

The feed speed is always increased or decreased so that the slack is kept within a certain range.

In this way, there is no need to separately install a signal cable or the like for interlock control between the winch and the feed device.

Moreover, according to this method, no tension is applied to the ropes or cables on the right side of the pulling device 18 in the figure by the ropes or cables on the left side, so the shorter the distance between the pulling devices, the greater the tension. Cables can be laid with low tension.

As described above, the cable installation method of the present invention can minimize the tension applied to the cable when installing cables all at once over a long section, and furthermore, the installation preparation work can be performed efficiently. Suitable for laying cables with relatively low tensile strength such as small communication cables and optical fiber cables.

[Brief explanation of drawings]

FIG. 1 is a conventional example, FIG. 2 and FIG. 5 are longitudinal cross-sectional views of the vicinity of a manhole and pipeline according to the method of the present invention, and FIGS. 3 and 4 are cross-sectional views of ropes suitable for implementing the present invention, respectively. and a side view of the cable feeder, each symbol indicates the one on the right. I, 'II, m... Manhole section, 4...
... Cable drum, 5 ... Cable, 6 ~
9... Manhole, 10-12.26-28.
...Take-up rope, 15.24...Winch, 1T...Plastic coating, 18...
...Cable feeding device, 20...Sag detection device, 23...Take-up rope group.

Claims (1)

[Scope of Claims] 1. In the case where an electric cable having a length greater than or equal to the sum of the lengths of a plurality of manhole sections is laid throughout the entire section, a length corresponding to the manhole section can be taken for each manhole section. After inserting the rope, all sections of the take-up ropes are connected in cascade to form a take-up rope group, and one end of the cable to be laid is connected to one end of the take-up rope group, and the other end of the take-up rope group is connected to one end of the take-up rope group. A cable laying method characterized by taking over a group of take-up ropes at a heel. 2. The cable laying method according to claim 1, wherein all the take-up ropes constituting the take-up rope group have a plastic jacket. 3. When installing an electric cable having a length equal to or more than the length of each section of a plurality of manhole sections throughout the entire section, after inserting a take-up rope of the length corresponding to that manhole section for each manhole section, The entire length of the take-up ropes is connected in cascade to form a take-up rope group, one end of the cable to be laid is connected to one end of the take-up rope group, and this take-up rope is connected to the other end of the take-up rope group. When taking over a group, 1 or 2 through which the cable passes
A cable feeding device is installed in each of the above manholes, and the feeding speed of the cable feeding device is controlled so that a certain amount of slack is generated on the cable feeding side in the manhole where the cable feeding device is installed. cable installation method.