JPH0636653B2 - Lightning protection method for two-way communication gas metering system - Google Patents

Description

The present invention relates to a lightning protection method used for a gas meter reading system by two-way communication, and in particular, 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 the system from damage due to damage.

(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, 17 and 18 are installed on the subscriber side, 16 is a security device, 17 is a terminal network control unit (NCU), 18 Is the communication controller (HC) 18
a, a gas meter 18b, a gas alarm 18c, 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 18 is collected and billing work for each gas consumer is performed. It monitors the warning information such as gas leaks that is reported from the terminal 18 at any time, and takes appropriate measures such as promptly taking appropriate measures according to the contents of the warning information.

Therefore, the communication line 20 is connected to the security device 16, the center network control device 17 and the controller 18a of the subscriber side terminal 18, and the commercial power source (AC100V) 21 stepped down by the transformer 19 is connected to the gas alarm device 18c. .

Further, the gas meter 18b contains another battery power source, a microcomputer, and a centralized monitoring system centering on the microcomputer.

By the way, since the control device 17 and the terminal 18 having these configurations are directly or indirectly connected to the communication line 20 and the power source 21, the external surge voltage caused by lightning or other causes is mainly transmitted through them. The circuit breakdown of the internal system has become 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 circuits of the respective devices that form the system from this type of lightning surge, conventionally, the withstand voltage of each of the internal circuits has been increased.

(Problems to be Solved by the Invention) However, according to this method, the withstand voltage is set higher than necessary in the normal state, and the entire system becomes expensive, and even if such withstand voltage is increased. 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. It is an object of the present invention to provide a lightning protection method for a two-way communication gas meter reading system, which enables effective protection against an external surge by grounding to the ground side through.

[Means for Solving the Problems] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a gas alarm device connected to a commercial power source side, a gas meter grounded to the ground, and a gas alarm device. A communication controller connected to an output end and an input / output end of the gas meter; and a center network control device connected to a communication side input / output end of the communication controller and a communication line. In a two-way communication gas meter reading system, a bypass circuit consisting of a combination of surge protection elements is provided in a stage preceding the commercial power supply side of the internal circuit of the gas alarm, and the ground end of the bypass circuit is connected to the communication controller. A bypass circuit consisting of a combination of surge protection elements, which is connected to the ground terminal and is provided in the preceding stage on the communication line side of the internal circuit of the center network control device. Provided, the ground end of the bypass circuit is connected to the ground end of the communication controller, further to the gas meter, a gap lower than the withstand voltage of each internal circuit of the gas alarm, gas meter, controller and center network control device. Provided is a lightning protection system for a two-way communication gas meter reading system, wherein one end of the gap is connected to a communication controller and a signal transmission line connecting a gas meter, and the other end is connected to a case of the gas meter.

(Operation) According to the above configuration, the surge voltage that invades on either line is grounded to the ground side through the signal transmission line and the gas meter, and does not enter the respective internal circuits.

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
Reference numeral 2 is a communication controller (HC), and 53 is a center network control unit (NCU).

The gas alarm 50 is a case 54 and AC100V pulled out from the case 54 and stepped down by the transformer 19.
And a gas alarm circuit section 56 having its input end connected to the power supply lines 21a and 21b from the connection plug 55 in the case 54.

The gas meter 51, which is outdoors and is connected to a gas pipe, has a case 57 in which a microcomputer, a control circuit unit 58 such as a shutoff valve drive circuit, a shutoff valve (not shown), a flow rate detection sensor, and the like. It has a built-in drive power supply.

The communication controller 52 includes a case 59 and a gas security system circuit section 60 provided in the case 59.

The center network control device 53 includes a case 61 and a center network control circuit unit 62 provided inside the case 61.

The circuit parts 60 and 62 of the controller 52 and the control device 53 are connected to the output end of the alarm device 50 via signal transmission lines 50a and 50b. The input / output terminal of the control circuit section 58 of the gas meter 51 is connected to the input / output terminal of the circuit section 60 via a signal transmission line 58a, and inside the controller 52, the one signal transmission line 50b side. Signal transmission line 58
It is connected via b.

The alarm device 50 has a grounding terminal 6 electrically connected to the case 54.
3 is provided, and a pair of varistor 64 forming a surge-proof bypass circuit is connected between the power supply lines 21a and 21b in the front stage of the circuit section 58, and the midpoint, that is, the ground end, is used for the grounding. It is connected to the terminal 63.

Further, the control device 53 is provided with a grounding terminal 65 which is electrically connected to the case similarly to the above, and the communication lines 20a and 20b provided therein are provided in the upstream side of the connection side of the circuit section 62 to the communication line 20. A pair of varistor 64 is connected between the two, similarly to the above, and the midpoint, that is, the ground end, is connected to the grounding terminal 65.

Further, the controller 52 is also provided with a grounding terminal 66 which is electrically connected to the case 59, and the grounding terminal 66 is provided.
The grounding terminals 63 and 65 provided in the alarm device 50 and the control device 53 are connected to each other through connection lines 67 and 68, respectively.

Inside the gas meter 51, one end is connected to the signal transmission line 58b, and the other end is connected to the case 5 of the gas meter 51.
A gap 72 consisting of a surge-proof element, which is connected to 7, is provided.

The withstand voltage of the gap 72 depends on the circuit parts 56, 5 described above.
It is set to be lower than the withstand voltage of 8, 60, 62 (a value of about 40 to 47 KV when the withstand voltage of each circuit part is set to 50 KV or more in the solid line). It has a function of bypassing to the gap 72 side before entering.

Each of the varistor 64 has a function of smoothing the instantaneous rise of the surge voltage, and the bypass circuit configured by this connects the surge voltage on the power supply lines 21a and 21b to the connection line 67 side through the grounding terminal 63. And is grounded to the ground side through the case 57 of the gas meter 51, the gas pipe, the LP gas cylinder, etc. through the signal transmission line 58b and the gap 72.

On the contrary, when a surge voltage enters from the communication line 20 side, it is grounded to the ground side through the bypass circuit and the gap 72 which are also formed by the varistor 64.

As described above, both surge voltage intrusion from the power supply 21 side and surge voltage intrusion from the communication line 20 side are bypassed to the ground side in the preceding stage of each circuit section, and the circuit section of each device is bypassed. It will protect you.

The controller 52 and the control device 53 may be housed in the same case, and the number of signal transmission lines is actually larger.

The power source 21 is also supplied to these, but even if an external surge is applied to them, they flow to the ground side through the bypass circuit on the alarm device 50 side. Absent.

In the embodiment shown in the figure, the grounding connecting line connecting the controller 52 and the gas meter 51 is eliminated, and one signal transmission line 58b is provided inside the case 59 on the controller 52 side.
Is connected to the grounding terminal 68 and is connected in parallel to the gap 72 side in the case of the gas meter 51 and in the front stage of the circuit portion 58, and the signal transmission line 58b is connected via this gap.
The surge voltage on the top is bypassed to this part, and it is grounded to the ground side.

In this embodiment, the gas meter 51 and the communication controller 5
The number of connections with 2 can be reduced by one, and wiring becomes easy.

FIG. 2 shows a second embodiment of the present invention. In this embodiment, in addition to the above embodiment, the signal transmission line 50b connecting the control device 53 and the alarm device 50 is also used as a surge resistant connection line.

That is, in this example, the middle point of the varistor 64 is connected to the signal transmission line 50b, and the controller 51 is internally connected to the ground terminal 66 and the signal transmission line 58b.

In this embodiment, the gas meter 51 and the communication controller 5
It is possible to reduce the number of connections between the two and one, and also reduce the number of connections between the controller 52 and the control device 53 by one, which further facilitates wiring.

[Effects of the Invention] As described in detail above with reference to the embodiments, in the lightning protection method for the two-way communication gas metering system according to the present invention, the surge voltage due to lightning or the like has entered either the communication line or the power supply. Even in such a case, since it escapes from the gas meter to the ground side through the bypass circuit in the preceding 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.

Further, according to the present invention, a simple bypass circuit composed of a combination of elements for surge withstand is added to the front stage of the circuit section, and a gap having a withstand voltage lower than that of the internal circuit is provided on the ground side to prevent surge voltage. Because you can protect
Since the configuration is simple and the existing circuit configuration is not changed at all, the configuration can be inexpensive, and the number of devices can be reduced and the size can be reduced 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 device 51 ... gas meter 52 ... communication controller 53 ... center network control device 56,58 , 60, 62 ... Circuit part 64 ... Varistor (protective element) 50a, 50b, 58a, 58b ... Signal transmission line 63, 65, 66, 70 ... Grounding terminal 67, 68 ... Connection line 72 ... gap

─────────────────────────────────────────────────── ─── 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 connected to a commercial power source side, a gas meter grounded to the ground, a communication controller connected to an output end of the gas alarm device and an input / output end of the gas meter. And a center network control device connected to a communication side input / output end of the communication controller and connected to a communication line, the commercial power supply side of the internal circuit of the gas alarm device. A bypass circuit consisting of a combination of surge protection elements is installed in the front stage of
The ground terminal of the bypass circuit is connected to the ground terminal of the communication controller, and a bypass circuit composed of a combination of surge protection elements is provided in the preceding stage on the communication line side of the internal circuit of the center network control device, Connect the ground end of the bypass circuit to the ground end of the communication controller,
Furthermore, in the gas meter, the gas alarm, the gas meter,
A gap lower than the withstand voltage of each internal circuit of the controller and the center network control device is provided, one end of which is connected to the signal transmission line connecting the communication controller and the gas meter, and the other end is connected to the case of the gas meter. Lightning protection method for two-way communication gas metering system.