JPS58803B2 - cable line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cable line, and more particularly to a cable line having a main cable connected to a signal source and a plurality of sets of branch lines for loads.

Emergency broadcast wiring is installed in buildings, underground malls, or tunnels, and conventionally used cable lines as shown in FIGS. 1a and 1b are examples of this type of wiring.

The cable line shown in FIG. 1A is one in which the amplifier 1 and each of the installed speakers 2 are individually connected by cables 3.

Therefore, in this case, it is necessary to wire each speaker 2 individually, which increases the amount of cables used and complicates the connection between the cables and the amplifier 1.

On the other hand, in the cable line shown in FIG.
is provided to perform branch connection of the speakers 2.

Therefore, with this method, the amount of cable used is small and the connection between the cable and the amplifier 1 is easy, but in the unlikely event that one of the speakers 2 is destroyed by a fire, or due to external damage, a short circuit or a ground fault occurs. If this occurs, the effect will extend to other speakers 2 through the main cable 4, and the emergency broadcast function will be lost.

In particular, these emergency broadcast speakers are installed at intervals of 20 to 50 meters, and for example, inside a building, they are installed throughout each floor of the building.
The impact would be extremely significant, as it would be impossible to make emergency announcements throughout the building.

The object of the present invention is to provide a cable line that eliminates such drawbacks and can reduce the influence on other loads even when any number of loads are short-circuited or grounded. A cable line having a plurality of sets of branch lines for loads on a main cable connected to a line is characterized in that a resistor is inserted in at least one of the branch lines of each set.

Examples will be described below.

FIG. 2 shows one embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

This cable line consists of a main cable 6 made of a fireproof and heat-resistant cable connected to the amplifier 1, a branch cable 7 connected to this, and a resistor with a resistance value of 50 to 200 Ω inserted in a part of the branch cable 7. 8, and a speaker 2 is connected to each branch cable 7.

FIG. 3 shows the structure of the branch connection part of this cable line, and the main cable 6 and the branch cable 7 to which the resistor 8 is connected are crimped or compressed connected at the branch connection part 9. The outer periphery of the branch connection 9 and the resistor 8 is covered with a fireproof and heat-resistant layer 10 made of mica, glass tape, asbestos, silicone, or other inorganic material, and the outer periphery is made of plastic such as vinyl or polyethylene. An insulating layer 11 is provided.

In a cable line having such a structure, a branch connection part 9 is formed at the speaker installation position of the main cable 6, and a resistor 8 is connected to one of the two cores of the branch cable 7. Wrap water and heat resistant tape over the top to make it fireproof.
A heat-resistant layer 10 is formed to protect the branch connection portion 9.

Then, an insulating treatment is applied thereon to form the insulating layer 11 using an insulating tape or injection molding of an insulating material.

Note that the resistor may be inserted into both of the two wires that make up the branch cable.

FIG. 5 shows a cross section of the trunk cable 6, in which the conductor 61
In addition to the insulating layer 63, the inclusion 64, and the sheath 65, it has a fireproof and heat-resistant layer 62.

In this cable line, each branch cable for each speaker is connected to the main cable via a resistor, so even if one of the speakers catches fire or is short-circuited or grounded, there will be no short-circuit or grounding current. Since it flows through the resistor, it can be reduced, and therefore damage to other speakers can be prevented, and emergency information can be transmitted by other speakers.

That is, even if a fire breaks out on one floor of a building, evacuation information can be transmitted to other floors.

As described above, the cable line of the present invention can reduce the influence on other loads even when an individual load is short-circuited or has a ground fault, and is an industrially effective device.

[Brief explanation of the drawing]

Figures 1a and b are circuit diagrams of conventional cable lines;
3 is a schematic sectional view of a branch connection portion, and FIG. 4 is a sectional view taken along line A-A in FIG. 2. In the figure, 1 is an amplifier, 2 is a speaker, 6 is a trunk cable, 7 is a branch cable, 8 is a resistor, 9 is a branch connection, 10 is a water-resistant and heat-resistant layer, and 11 is an insulating layer.

Claims (1)

[Scope of Claims] In a cable line in which a main cable connected to one signal source has a plurality of sets of branch lines for loads, a resistor is inserted in at least one of the branch lines of each set. Characteristic cable line. 2. The cable line according to claim 1, wherein the resistor is coated with a fire-resistant, heat-resistant, and waterproof electrically insulating material together with the branch connection portion and the branch line of the main cable. 3. The cable line according to claim 1 or 2, wherein the signal is an audio signal and the load is a speaker.