JPS6028332A - Information transmission network - Google Patents

Abstract

PURPOSE:To improve the operating ratio by allowing a main power supply to apply power via a power transmission cable of a main cable and supplying power with a stepped-down voltage via a branch cable and also transmitting information to an information transmission device connected to a coupler via the branch cable to unify the supply of large power to the entire system. CONSTITUTION:The couplers 6 are provided to the main cable 6 at a proper interval and an MODEM8 functioning as an information transmitter is connected respectively to each coupler 6 via the branch cable 7. The coupler 6 relays an information signal transmitted via an information transmission cable 2 of the main cable 4 to the said branch cable 7 and the information transmission among the information transmitters (MODEMs) 8 is performed via the branch cable 7 and the main cable 4 in this way. Further, the said coupler 6 receives the power supplied through the power transmission cable 3 of the main cable 4 while voltage step-down and supplies the power to the MODEM8 via the branch cable 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an information transmission network that can easily supply power to information transmission equipment and that can reduce system costs.

[Technical background of the invention and its problems]

A so-called broadband network that applies CATV technology is known as a type of local area network (LAN) that is the core of an OA (office automation) system. This system has attracted attention as a cost-effective way to transmit information such as voice information from telephone calls, code information created by word processors, image information stored in optical disk devices, and even TV information and video information. ing.

By the way, as the amount of information accommodated in such a system increases, it becomes necessary to further increase the operating rate of the entire network. To this end, it is necessary not only to improve the reliability of the various devices that make up the network, but also to unify power management for the various devices, and to take into account operational considerations. Furthermore, as the telephone system is accommodated in the network, it becomes necessary to provide power with measures against power outages.

To meet this demand for power supply,
BACKGROUND ART A star network in a private branch telephone exchange system is known. In this example, a large-capacity power supply is provided in the main body of the switch, and power is supplied from the main body of the switch to telephones connected thereto via twisted pair wires for information transmission provided in a star shape. However, the twisted pair wires supply power only to telephones, and their power capacity is extremely small. Therefore, it was impossible to apply this technique to the above-mentioned system.

On the other hand, in a CATV system using a coaxial cable as an information transmission medium, for example, a repeater amplifier is provided every time the coaxial cable is laid for about 500 meters, and power is supplied to the repeater amplifier via the coaxial cable. ing. However, even in this case, the target of power supply is limited to the relay amplifier, and power is locally supplied by small capacity power supplies of, for example, 30V and IA, provided at appropriate intervals. However, it was difficult to apply it to the above-mentioned system.

That is, information transmission networks tend to become larger and larger, and their network configurations are becoming more diverse, such as bus, ring, and tree types. Then, it becomes necessary to supply large amounts of power on the order of KW via these networks. Therefore, it has been difficult to apply the above-mentioned small capacity power supply technology.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to provide reliable and effective power supply to various information transmission devices in systems that perform various large-capacity information transmission. It is an object of the present invention to provide a highly practical information transmission system that can sufficiently cope with layout changes, etc., without causing an increase in system costs.

[Summary of the invention]

The present invention provides a plurality of cassillas via a trunk cable that includes an information transmission cable and a power transmission cable, and also allows power to be supplied from the main power supply through the power transmission cable of the trunk cable. , the Cassilla relays the information transmission via the information transmission cable, steps down and extracts the power from the power transmission cable, and supplies the information transmission equipment connected to the coupler via the branch cable. In addition to supplying step-down power through the branch cable, information is also transmitted.

〔Effect of the invention〕

Thus, according to the present invention, large-capacity power is supplied to each of the plurality of couplers via the main cable, and each coupler supplies the reduced-voltage small-capacity power from each coupler to the information transmission equipment via the branch cable. becomes possible. Therefore, it is possible to centralize the large-capacity power supply to the entire system, improve its operating rate, and improve operation and maintenance management. Furthermore, if the main power source device is equipped with uninterruptible measures, telephones can be connected to the network in accordance with the technical standards for private branch exchanges. Therefore, it is possible to effectively promote an increase in the amount of information transmitted in the system.

In addition, as described later, the supply voltage from the main cable is 30
If the voltage is set to 0 V or less and the secondary side capacity is set to 3 kVA or less, it can be installed relatively easily as a low-voltage indoor installation within the range specified by electric power equipment technical standards. In addition, by making the branch cable a weak current (low power) circuit of 30V or less and 38V or less, the installation work can be facilitated, and changes in the layout of information transmission equipment can be easily handled. It is possible and highly practical. Further, by distributing a plurality of main power supply devices and each having an appropriate redundant capacity, the reliability of the entire system can be improved.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An information transmission network according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an embodiment network. This network is structured around the head office.
A plurality of trunk cables 4 each consisting of an information transmission cable 2 and a power transmission cable 3 each composed of one or two coaxial cables are provided, each of which constitutes a segment. Main power supply devices 5 are connected to the power transmission cable 3 of the trunk cable 4 at a plurality of locations to supply power.

The main cable 4 is provided with cutters 6 at appropriate intervals, and the branch cable 7 is connected to the cutter 026.
A modem 8, which is an information transmission device, is connected to each terminal via the terminal. Various information terminals 9 are connected to this modem 8, respectively. Incidentally, the amplifier 10 provided at an appropriate location on the trunk cable 4 is for compensating for attenuation of the information signal transmitted via the information transmission cable 2.

The cassilla 6 relays the information signal transmitted via the information transmission cable 2 of the trunk cable 4 between the branch cable 7 and the information transmission equipment (modem). Information transmission between the two terminals 8 is performed via the branch cable 7 and the trunk cable 4.

Further, the cassilla 6 lowers the voltage of the power supplied via the power transmission cable 3 of the trunk cable 4, extracts it, and supplies it to the modem 8 via the branch cable 7. This branch cable 7 is not, for example, a coaxial cable for information transmission, and using this coaxial cable, voltage-down, reduced-capacity power is supplied as in the conventional CATV system. In addition, when information transmission is performed using an optical fiber using light as a medium, an optical fiber with a twisted pair wire attached thereto is used as the branch cable 7, and this twisted pair wire is used to transmit the voltage reduced. What is necessary is to supply a small amount of power.

In this way, according to this network, large-capacity power is transmitted to the cassilla 6 via the power transmission cable 3 of the trunk cable 4.
This drives each coupler 6 with electric power, and each coupler 6 steps down and extracts the large-capacity electric power into a small-capacity electric power, which is then supplied to the modem 8 via the branch cable 7. Each modem 8 is driven respectively. Power can be centrally (uniformly) supplied to the coupler 6, modem 8, relay amplifier 10, etc. that construct the network by the power supply device 5. Therefore, it becomes possible to carry out the operation management and maintenance management effectively.

Therefore, it is possible to sufficiently cope with the increase in the amount of information that the system accommodates, and to ensure its reliability, resulting in great practical effects.

By the way, the configuration scale of the network, such as the number of segments connected to the headend 1 and the number of Kagura 6 for each segment, depends on the design concept of the OA system,
It varies depending on the specifications of the office where the system is installed. Therefore, although the advantages of this network cannot be discussed in general terms, its effects can be fully understood by assuming an average power supply model as shown below. That is, suppose that the average model is expressed as follows.

Average modem power consumption: 15 W / Modem amplifier power consumption: Average 30 W / Number of amplifier modems connected: 0 units / Number of segment amplifiers: 5 units / Segment Branch cable power transmission efficiency = 90 Main cable power transmission efficiency: 90% In addition, above The power transmission efficiency of each cable is due to the coupler 6 in addition to the loss due to the cable itself. It also includes power conversion efficiency, etc. Assuming such a model, the amount of power required to be supplied from the main power supply device 5 to each segment is approximately 1.5 kW. Therefore, by using a main power supply 5 having a capacity of about 1.5 kW per segment, the network shown in FIG. 1 described above can be effectively powered and operated.

By the way, when constructing a network including such a power system, it is necessary to satisfy various legal constraints. In other words, the laws and regulations related to local area network power supply include ``Electric Power Equipment Technical Standards,'' ``Extension Line Regulations,'' ``Electrical Contractor Act Construction Ordinance,'' and ``CAT.
``Electrical Maintenance'' and ``Technical Standards for Internal Switching Equipment, etc.''. To summarize the restrictions indicated by these regulations: (i) Grounding work is not required for equipment, etc. that is powered via an isolation transformer whose secondary side is 300V or less and whose capacity is 3kVA or less. .

()1) If the device consumes less than 30V and 3A,
This can be considered a weak current (low force) circuit, and power transmission via a signal (coaxial) cable is possible. Also, the work does not need to be done by an electrician.

011) For the telephone system, it is sufficient to have a backup power supply capable of supplying power for 3 hours at peak current consumption.

etc. However, when such equipment conditions are taken into consideration, the power consumption per segment is approximately 1.5%, as mentioned above.
Since a power capacity of kW is required, in order to supply power to each segment from one main power supply, it is necessary to perform grounding work on each device. This leads to an increase in installation costs and also leads to centralization (increased capacity) of the main power supply device. Furthermore, failure of the main power supply device brings about a system down of the entire network, causing a decrease in its operating rate.

Therefore, if a main power supply device is provided independently for each segment, there are great practical advantages, such as eliminating the need for the above-mentioned grounding work for each device.

Furthermore, if a plurality of main power supplies 5 are arranged in a distributed manner along the trunk cable 4 in each segment, if one main power supply fails, other normal main power supplies will function as a redundant system. As a result, it is possible to effectively avoid the problem of stopping the operation of the entire system.

Further, by distributing the main power supply devices in this manner, the reliability required of each main power supply device does not become extremely high, and the cost can be reduced. Further, by distributing the main power supply devices, it is possible to disperse the current flowing on the trunk cable 4, thereby making it possible to reduce the capacity of the cable and reduce its installation cost.

Furthermore, secondarily, by reducing the capacity of each main power supply,
Since natural air cooling operation is also possible, noise reduction can also be expected.

Now, in such a network, there are no legal restrictions on the form of power transmitted via the main cable 4 and the power transmitted via the branch cable 7, and even if AC power is supplied, Alternatively, direct current power supply may be used.

Incidentally, in CATV systems, alternating current power supply is used to avoid galvanic corrosion at connectors. However, unlike the above-mentioned CATv, local area networks for offices are not exposed to high humidity, and galvanic corrosion can be completely prevented by selecting the so-called plating material of the connector, so AC power supply is not suitable for local area networks. Or 1
It is possible to adopt either district current power supply. Now, if we consider this power supply method, we can consider the forms shown in FIGS. 2(a) to 2(d) as a power supply method in one segment. That is, the combinations of the power feeding system in the trunk cable 4 and the power feeding system in the branch cable 7 include the DC/DC system shown in FIG. 2(a), the DC/AC system shown in FIG. 2(b), and the DC/AC system shown in FIG. ) The AC/AC method shown in
The AC/DC system shown in FIG. 2(d) can be considered.

In FIG. 2, the names shown in the blocks indicate the devices that implement them, <>-i: The numerical value shown is the relative cost of the unit power. Further, the coupler number coefficient α indicates a margin for adding or changing modems after the network is installed. Note that the above relative cost is given to estimate the tendency based on the number of component parts of the device, etc., and it goes without saying that it changes depending on the scale of mass production, etc., and is only a rough guideline.

Under such an assumption, Figure 3 shows the relative cost of the power supply system of each segment a and b when the two-cup number coefficient α changes.Characteristics A, B, C
, D are shown corresponding to each method shown in FIGS. 2(a) to 2(d).

As is clear from the trends shown in FIG. 3, the relative cost is highest for the AC/DC power supply system, followed by the DC/AC power supply system. Therefore, when the coefficient α is "l", the relative installation cost is the lowest when the DC/DC power supply system is adopted, and the coefficient α is r 1.5.
It can be seen that in the case of exceeding J, the installation cost can be reduced by adopting the AC/AC power supply system. This can be said to be because when the above-mentioned AC/AC power supply system is adopted, the power system of the coupler 6 can be simply constituted by a transformer, which is advantageous in reducing costs. Note that this is related to the modeled network as described above, and it cannot be said that the actual cost is sufficiently reflected. However, when the coefficient α is large, it has a sufficiently large meaning as a tendency, and as the capacity of the network increases due to the addition of Kagura 6, we believe that the adoption of the AC/AC power supply method described above is very high. It will be done.

On the other hand, due to the above-mentioned legal restrictions, it is advantageous for network installation work to reduce the voltage of the power transmitted via the main cable 4 to 300V or less, but in general, the higher the voltage, the better the power transmission efficiency. Moreover, the voltage drop at that time is also small.

On the other hand, in order to reduce the cost of the system by effectively using commercially available power supply components, it is desirable that the voltage be lower. FIG. 4 shows the relationship between the supply voltage of the transmission power in the trunk cable 4, the transmission efficiency, and the voltage drop, which was determined based on this viewpoint. However, this relationship applies to 600'V, CV type,
Segment length 4 using 3.5m + N2 diameter, with 20 units of 75W load of 400Hz AC power installed at equal intervals.
This is about the 00m network. As shown in FIG. 4, when the supply voltage is 150V or less, the transmission efficiency
It can be seen that the voltage drop Y increases rapidly below 5V. Conversely, if the supply voltage is approximately 2. If it is equal to or higher than QOV, no significant difference is found in transmission efficiency X and voltage drop Y.

For this reason, 200V power supply devices are becoming popular, and system costs can be expected to be reduced by using more of these parts. Supply voltage from 2
If you set it to around 00V, when building a network,
High practical advantages. In this case, if the output voltage fluctuation of the main power supply device 5 is about ±5 inches, the voltage supplied to the coupler 6 should be 200 V (+5% to -14 inches).

The above explanation was based on the power system model with one modem 8 connected to one Kagura 6, but
A distributor may be provided between the coupler 6 and the modem 8 to connect a plurality of modems 8, and the coupler 6 itself may be of a multi-branch type to connect a plurality of coaxial cables. Considering such an embodiment, in order to supply power to equipment with a branch cable of 7 or less as a weak current (small power) circuit and to simplify the configuration, the capacity should be 30V or less and 3. It is necessary to set it to 8 or less.

Therefore, in order to satisfy such specifications, the number of modems 8 connected to the Kagura 6, that is, the number of branch cables 7, may be set to four at maximum. If you do this, cup 26
Assume that the maximum power load supplied by the main cable 4 is (15W x 4) = 60W, the voltage drop at 7° and 6 is 16°, and the power from the main cable 4 is stepped down to 30V and supplied to the branch cable 7. For example, the voltage supplied to the coupler 6 is 30V (+5% to -30%) in consideration of the above fluctuation.

Therefore, even when the maximum load is 60 W, the current supplied via the branch cable 7 is about 2.9 A at the maximum, which fully satisfies the above-mentioned conditions. Therefore, it is possible to supply power to the modem 8 using the information transmission cable as the branch cable 7. In addition, by doing this, it is possible to easily change the network below the branch cable without relying on electrical engineers, and it is possible to move or change network equipment due to changes in office layout, etc. can be dealt with effectively and easily.

Next, when transmitting power using an AC power supply method,
As a factor for determining the above AC frequency, the coupler 6
etc., the size of the transformer installed in the main cable 4, the voltage drop in the trunk cable 4, etc. In general, there is a tendency that by increasing the frequency, it is possible to make the transformer smaller, and by lowering the frequency, it is possible to reduce the voltage drop. FIG. 5 shows the relationship between the transformer size and the frequency when the size of the transformer incorporated in the coupler 6 at a maximum load of 60 W is modeled as a cube. The above transformer has a frequency of 3
For those below kHz m, S 1-Fe is used as the core, and for frequencies above 3 kHz, ferrite is used as the core.

As shown in this figure, the transformer size with respect to frequency is 3o, whereas it is small at frequencies below 300Hz and becomes small at frequencies above 3kHz.

There is no change in magnitude at ~3 kHz. Still, Figure 6 shows the change in effective resistance with respect to the frequency of transmitted power in the power transmission cable, but from this relationship, the effect of reactance appears as the frequency increases, and the effective resistance decreases at 3 kHz or higher. A sudden increase in resistance is read. By taking these points into account, when adopting AC power supply, it is possible to reduce the size of the transformer by setting the frequency to around 400Hz, and to suppress losses in power cables to provide effective power supply. I am made aware of what will happen.

When configuring a network under these specifications, the cost can be reduced by selecting the thinnest power transmission cable 3 in the trunk cable 4 within the range of permissible transmission efficiency and voltage drop. It is advantageous in terms of target and installation work. Preferably, the size of the power transmission cable 3 is equal to or smaller than that of the signal transmission cable 2 attached to the power transmission cable 3, in order to avoid an increase in the bending radius of the cable during installation work. FIG. 7 shows the effective resistance L1, voltage drop M1, and transmission efficiency N of the power cable when transmitting AC power of 200 V and 40' OHZ by varying the cable size. However, the cable size is shown here as a conductor cross-sectional area. From the characteristics shown in Figure 7, for example, if you choose a cable with a conductor cross-sectional area of 35 x 2, the voltage drop I/'i will be about 9% and the transmission efficiency will be about 94%. It turns out that you are fully satisfied.

Since the size of such a cable is comparable to that of the coaxial cable serving as the information transmission cable 2, it does not pose any problem during installation work.

In this way, this network can be realized inexpensively and efficiently, and its practical advantages are enormous.

Note that the present invention is not limited to the above embodiments. For example, if light is used as the information transmission medium, an optical fiber may be used as the signal transmission cable.In this case, since the branch cable 7 cannot provide staining force to the optical fiber, twisted pair wires are used as described above. It may be installed in parallel to supply electricity. There is also no need for the network to be configured in a path centered around the head end 1. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a network according to an embodiment of the present invention, and FIGS. 2 to 7 are diagrams each showing a consideration of power transmission of the embodiment network and its characteristics. 1... Head end, 2... Information transmission cable,
3... Power transmission cable, 4... Trunk cable,
5... Main power supply device, 6... Cassilla, 7... Branch cable, 8... Modem (information transmission equipment), 9...
Information terminal, 10...relay amplifier.・ Figure 1 Figure 2 (a) ■゛ Figure 3 Cuff...2'; [4th stage Otsu □ φ---Ll))

Claims (5)

[Claims] (1) A trunk cable that includes an information transmission cable and a power transmission cable, a main power supply device that supplies power to the power transmission cable of the trunk cable, and a main power supply device that is connected to the trunk cable and that transmits the information. A plurality of cassillas that relay information transmission via the transmission cable and step down and extract the power transmitted via the power transmission cable, and a plurality of cassillas connected to each of these cassillas via branch cables. An information transmission network comprising: a plurality of information transmission devices that receive the step-down power through the branch cable and transmit information through the branch cable. (2) The branch cable consists only of an information transmission cable, and not only transmits information through this information transmission cable, but also supplies the power reduced at Cassila to the information transmission equipment through the information transmission cable. An information transmission network according to claim 1. (3) The information transmission network according to claim 1, wherein a plurality of main power supply devices are distributed along a trunk cable. (4) The power supplied from the main power supply device to the cup 2 via the main cable and the power supplied from the above-mentioned Cassilla to the information transmission equipment via the branch cable are both AC power or DC power. Information transmission network described in scope 1 ◇ (5) The information transmission network according to claim 1, wherein the branch cable consists of an information transmission cable and a power transmission cable attached to the information transmission cable.