JPH0636654B2 - Lightning protection system for gas metering system - Google Patents

Description

Description: [Object of the Invention] (Industrial field of application) The present invention relates to a lightning protection method used for a gas meter reading system by communication, and particularly, a system by an external surge intrusion from both a commercial power source side or a communication line. The present invention relates to a lightning protection method capable of effectively protecting from destruction.

(Prior Art) For example, a center and a terminal are installed at an LPG dealer and an LPG consumer, respectively, and a communication line such as a telephone line is connected between them, and the terminal to the center through this communication line, based on a request from the center. A two-way communication gas meter reading system is being considered, which is capable of reporting gas meter reading data as well as warning information such as gas leaks at any time.

FIG. 3 shows a general configuration of this type of meter reading system, where 11 is a center and 12 is a center network control device (C
NCU), 13 and 14 are subscriber exchanges, 15 is a no-rigging trunk, 16 and 17 are installed on the subscriber side, 16 is a protector, 17 is a controller 17a,
The terminal includes a gas meter 17b, a gas alarm 17c, and the like.

The center 11 is, for example, a terminal installed in an appropriate place of an LPG dealer and installed in each of a large number of gas consumers (only one terminal is shown in the figure, but a large number of terminals actually exist). ) Is requested once a month to report gas meter reading data, and in response to this request, the gas meter reading data reported from the terminal 17 is collected and billing work is performed for each gas consumer. It monitors the warning information such as gas leakage which is reported from the terminal 17 at any time, and takes appropriate measures such as promptly taking appropriate measures according to the content of the warning information.

Therefore, of the subscriber side terminals 17, the controller 17
The communication line 20 and the commercial power source 21 for driving are connected to a, and the commercial power source 21 is connected to the gas alarm device 17c.

Further, the gas meter 17b includes another battery power source, a microcomputer, and a centralized monitoring system centering on the microcomputer.

By the way, since the terminal 17 configured as described above is directly or indirectly connected to the communication line 20 and the power source 21, the internal system of the internal system caused by the external surge voltage due to lightning or other causes is mainly transmitted. Circuit destruction is a problem.

There are two types of external surge voltage caused by lightning, and they are distinguished as direct lightning and induced lightning. However, straight line lightning generates a huge amount of energy, so any measure is taken to protect the equipment from destruction. This is not possible, and the damage probability is extremely small, so it is ignored here.

However, there is a high probability that the induced lightning generated on the power transmission line for the commercial power supply and the communication line will occur, and the surge voltage generated by this will enter the equipment while repeatedly attenuating and reflecting the power line and the communication line.

As is well known, semiconductor elements such as ICs have a characteristic of being weaker in surge voltage than conventional vacuum tubes or mechanical contacts, and have no self-healing property, so that they are almost always destroyed. However, even if the circuit is not destroyed, it may malfunction or deteriorate, and many cases of actual damage have been reported.

As a measure for protecting the internal circuit of each device that constitutes a system from this type of lightning surge, conventionally, the withstand voltage of the internal circuit of each device has been increased.

(Problems to be Solved by the Invention) However, according to this method, the withstand voltage is set to an unnecessarily high withstand voltage in the normal state, which makes the entire system expensive and even if the withstand voltage is increased in this way. It was useless when a surge voltage higher than the withstand voltage of the internal circuit was applied.

Also, after it became clear that the damage caused by lightning was significant, a lightning protection adapter was added as a separate component, but it is expensive and the arrangement of the equipment becomes complicated, and depending on the arrangement etc. it is effective. There was a fear that it would not work.

The present invention is to solve the above problems, and a circuit for bypassing a surge voltage from both a communication line and a power supply is provided in the preceding stage of each internal circuit, and the ground side of the bypass circuit is provided in a gas meter. An object of the present invention is to provide a lightning protection method for a gas meter reading system, which is capable of effectively protecting against an external surge by grounding to the ground side through.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a gas alarm device,
A gas meter reading system comprising a controller connected to an output terminal of the gas alarm and an input / output terminal of a gas meter with a built-in microcomputer, and a communication side input / output terminal connected to a communication line side, Alternatively, a power supply side bypass circuit consisting of a combination of surge protection elements is provided in the front stage of the power supply stage in the internal circuit provided in the controller, and a fuse is provided in the power supply line between the power supply side bypass circuit and the connection plug. A communication line side bypass circuit consisting of a combination of surge resistant elements is provided in the preceding stage of the communication line connection side of the controller, and the ground ends of the power supply side bypass circuit and the communication line side bypass circuit are grounded to the gas meter side, Furthermore, the plug for connecting the gas alarm device and the plug for connecting the controller are arranged close to each other.

(Operation) With the above configuration, the surge voltage that invaded on either line was grounded to the ground side through the gas meter, and a voltage higher than the withstand voltage of the internal circuit was applied without invading each internal circuit. Effective protection, even if.
Also, the fuse protects the circuit by blowing when an excessive surge flows. Furthermore, since the gas alarm device connection plug and the controller connection plug are close to each other, the voltage drop between the plugs is small, and surges from the power supply side are given priority to the bypass circuit on the power supply side. The internal circuit on the side not provided with the side bypass circuit is protected.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.

In the figure, 50 is a gas alarm, 51 is a gas meter, and 5
2 is a controller.

The input end of the gas alarm device 50 is connected to the commercial power supply 21, the output end is connected to the input side of the controller 52, and when a gas leak or the like occurs, an alarm output is output to the controller 52 side.

Further, the gas meter 51 has a monitoring system such as a microcomputer, a shutoff valve drive circuit, a shutoff valve, and a flow rate sensor, which are not shown therein, and is connected to the controller 52 in order to exchange data that changes from moment to moment. The output terminal is connected to the input / output terminal of the controller 52.

The controller 52 has one end connected to the commercial power supply 21 side via the connection plug 53 and the other end connected to the protector 5
4 is connected to the communication line 20 side.

A power supply side bypass circuit including a fuse 55 and a pair of varistor 56 is provided between the power supply lines 21a and 21b of the commercial power supply 21 at a stage before the power supply stage of the controller 52, and between the varistor 56, that is, the ground. The end is an input / output line 51 for the gas meter 51.
It is connected to a and 51b through a varistor 56.

A communication line bypass circuit including an arrester 57 is provided between the communication lines 20a and 20b of the communication line 20 in the preceding stage of the communication side circuit unit of the controller 52.
The middle point of the arrester 57, that is, the ground terminal is connected to the ground terminal of the power supply side bypass circuit.

In the above configuration, when a surge such as a lightning surge enters the power supply 21 side, this surge voltage flows to the gas meter 51 side through the bypass circuit including the combination of the fuse 55 and the varistor 56, and then to the ground side through the bypass circuit. Be grounded.

That is, the varistor 56 has a function of smoothing the surge voltage that instantaneously rises.

The withstand voltage inside the normal circuit is set to 5 KV or more, but by setting the withstand voltage of the varistor 56 to a value lower than this, the surge flows through this portion and is bypassed to the ground side. Become.

Note that if an excessive surge flows, the fuse 55 is blown to protect the circuit.

Further, according to this configuration, although no surge countermeasure is provided for the alarm device 50 side, the connection plug 58 for the power source 21 side is connected to the connection plug 53 for the controller 52 side.
If there is a surge on the power supply 21 side, it will not flow inside the alarm device 50 but will flow preferentially to the bypass circuit side even if the surge is on the power supply 21 side. Protect 50 internal circuits.

Next, when a surge is placed on the communication lines 20a and 20b, the surge is bypassed to the ground side through the arrester 57 and the gas meter 51 as described above.

The arrester 57 has a function of smoothing the voltage that instantaneously rises almost like the varistor, and protects the internal circuit of the controller 52 by this.

Next, FIG. 2 shows a second embodiment of the present invention.

In the embodiment shown in the figure, a bypass circuit composed of a combination of a fuse 55 and a pair of varistor 56 is provided in a stage preceding the power stage of the alarm device 50.

Then, this grounding end is connected to the arrester 57 via the connecting wire 59.
Is connected to the grounded end of and the gas meter 51 side.

In this embodiment, a bypass circuit is not provided on the power supply side of the controller 52, but the surge voltage preferentially flows through this bypass circuit by arranging the connection plugs 53 and 58 close to each other.
Will protect the internal circuit of.

[Effects of the Invention] As described in detail above with reference to the embodiments, in the lightning protection system for a gas metering system according to the present invention, a surge voltage due to lightning or the like may enter either the communication line or the power supply. However, since it escapes from the gas meter to the ground side through the bypass circuit in the previous stage of the internal circuit, the elements of the internal circuit can be protected even if the withstand voltage characteristics of each device are not sufficient. In addition, since the fuse is installed in the power supply line on the connection plug side of the power supply side bypass circuit, the fuse can be blown to protect the circuit when an excessive surge flows. Furthermore, because the gas alarm device connection plug and the controller connection plug are placed close to each other, the voltage drop between the plugs is small, and even if a surge enters from the power supply side, the surge is given priority to the power supply side bypass circuit. It is possible to protect the internal circuit of a device (gas alarm or controller) that does not have a bypass circuit.

Further, according to the present invention, since a surge voltage can be protected simply by adding a simple bypass circuit consisting of a combination of elements for surge resistance to the front stage of the circuit section, the configuration is simple and the existing circuit configuration is no matter what. Since it does not need to be changed, it can be constructed at a low cost and can be made compact without increasing the number of devices to be arranged as compared with the case where a conventional lightning protection unit is externally added.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration according to a first embodiment of the present invention, FIG. 2 is a block diagram showing an electrical configuration according to the second embodiment, and FIG. 3 is a conventional two-way communication gas meter reading system. 3 is a block diagram showing the configuration of FIG. 20 ... communication line 20a, 20b ... communication line 21 ... commercial power supply 21a, 21b ... power supply line 50 ... gas alarm 51 ... gas meter 52 ... controller 56 ... varistor (constitutes a bypass circuit on the power supply side 57) Arrester (surge protection element that constitutes the bypass circuit on the communication line side)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // G01F 15/06 9107-2F

Claims (1)

[Claims] 1. A gas alarm device, and a controller connected to an output end of the gas alarm device and to an input / output end of a gas meter with a built-in microcomputer and a communication side input / output end connected to a communication line side. In the gas meter reading system, a power supply side bypass circuit composed of a combination of surge protection elements is provided at a stage before the power supply stage in the internal circuit provided in the gas alarm device or the controller, and the power supply side bypass circuit and a connection plug are provided. A fuse is provided in the power supply line between the two, and a communication line bypass circuit composed of a combination of surge resistant elements is provided in the preceding stage of the communication line connection side of the controller, and the power supply side bypass circuit and the communication line bypass circuit are grounded. The end is grounded to the gas meter side, and the connection plug for the gas alarm and the connection plug for the controller are placed close to each other. Lightning protection method for gas metering system characterized by