JPH11339627A - Lightning failure protective method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high lightning protection reliability at a relatively low cost by physically cutting off a communication line and a commercial power line with a prescribed circuit breaker when the detected lightning current or voltage exceeds the threshold predetermined in consideration of the tolerable overcurrent or overvoltage of a communication apparatus. SOLUTION: A lightning protective device 20 is inserted between a communication line connecting terminal 11 and a communication line 51. When a lightning current generated appears on the communication line 51, a voltage V1 is induced on the secondary winding by a lightning current flowing in the primary winding of a current transformer 21, and the voltage V1 is applied to an integrating circuit 22. An integrated output voltage Vc proportional to the peak level of the lightning current is obtained by integration. A relay 24 is operated to physically cut off the communication line connecting terminal 11 and the communication line 51 only when the peak of the lightning current wave-form exceeds the threshold set in a comparator 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to protect various communication devices, such as home telephones, facsimile machines, computer network equipment, private branch exchanges, to which both communication lines and commercial power lines are connected, from failures due to lightning strikes. The present invention relates to a lightning damage protection method and device.

[0002]

2. Description of the Related Art In recent years, various information services using the Internet and the like have begun to spread rapidly to companies and homes. The construction of information and communication networks is being actively pursued.

[0003] On such a network, communication devices to which both a communication line and a commercial power line are connected, such as a home telephone, a computer, a modem device, a computer network device, and a private branch exchange, are often used. In addition, telephones, facsimile machines, and the like of ordinary households also use ICs, L
A large number of electronic circuits such as SI must be mounted, and most of them use a commercial power supply.

In various communication devices to which both the communication line and the commercial power line are connected, a surge generated by a lightning strike or the like intrudes from the communication line or the commercial power line.
If the surge voltage exceeds the withstand voltage of the communication device, the circuit breaks down the circuit inside the communication device and moves to the opposite side of the intrusion route, so that a failure occurs in the communication device. For example, when a surge enters from a communication line, insulation is broken in a part of the communication device, and the surge escapes to the commercial power line side. Further, when a surge enters from a commercial power supply line, insulation is broken in a part of the communication device, and the surge escapes to the communication line side.

For this reason, various types of lightning protection technology for communication devices have been conventionally studied. A conventional lightning protection technique will be described with reference to FIG. FIG. 4A shows a technique called a bypass arrester method. In this technology, the bypass arrester attached to the communication line and the commercial power line operates due to the overvoltage caused by the lightning current, and the voltage between the communication line and the commercial power line is kept below the breakdown voltage of the device. Is prevented. As a bypass arrester, a lightning arrester or a varistor is used.

FIG. 4B shows a technique called a common grounding method. In this technique, the ground line of the communication line and the ground line of the commercial power line are commonly connected to ground. Therefore, since a large potential difference does not occur between the communication line and the commercial power line, it is possible to prevent an overvoltage from being applied to the communication device. 4C and 4D show a technique called an insulation method. According to this technology, an insulation transformer is inserted between a communication line or a commercial power line and a communication device to reliably electrically insulate the communication device from the communication line or the commercial power line, and an overvoltage is applied to the communication device. To prevent it from being done.

[0007]

In the above-mentioned bypass arrester method, even if a current intruding from a communication line or a commercial power line flows into the bypass arrester when a lightning strike occurs, the communication between the communication line and the commercial power line is prevented. Naturally generates a potential difference, and it is essentially unavoidable that a voltage is applied to the device up to near the breakdown voltage of the device.

Further, if the common grounding method is applied to a communication device used in an existing house, a high cost is required because the house needs to be repaired. Furthermore, with regard to the insulation method using an insulation transformer, the insulation transformer itself is expensive and a relatively large installation space is required, so that it is difficult to introduce the insulation method into communication equipment in ordinary houses.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for protecting against lightning damage, which realizes high reliability of lightning damage protection at a relatively low cost.

[0010]

According to a first aspect of the present invention, there is provided a lightning protection method for a communication device to which a communication line and a commercial power supply line are connected. A lightning current or a lightning voltage that enters the communication device from at least one of the power supply lines is detected, and the detected lightning current or lightning voltage is determined in advance in consideration of the overvoltage tolerance or the overcurrent tolerance of the communication device. Compared to the threshold, if the detected lightning current or lightning voltage exceeds the threshold,
At least one of the communication line and the commercial power line is physically separated from the communication device using a predetermined circuit breaker.

According to the present invention, when a lightning current or a lightning voltage exceeding a threshold enters a communication device, at least one of the communication line and the commercial power line is physically disconnected from the communication device by the circuit breaker. Therefore, the communication device can be reliably protected from the lightning current appearing on the communication line or the commercial power line. 3. The lightning protection device according to claim 2, wherein the communication device is connected to at least one of a communication line and a commercial power line connected to the communication device. A lightning current detection circuit that detects a signal corresponding to a level and a waveform of a lightning current that intrudes into the communication device; and a signal detected by the lightning current detection circuit, which is predetermined in consideration of an overvoltage tolerance or an overcurrent tolerance of the communication device. A comparison circuit for comparing with a threshold value, and a switch circuit for disconnecting at least one of a communication line and a commercial power line connected to the communication device from the communication device according to a comparison result of the comparison circuit. Features.

According to the present invention, when a lightning current exceeding a threshold value enters the communication device, the switch circuit operates to disconnect at least one of the communication line and the commercial power line from the communication device. Therefore, the communication device can be reliably protected from the lightning current appearing on the communication line or the commercial power line. In addition, since the lightning current detection circuit detects a signal corresponding to the level and waveform of the intruding lightning current, it is possible to distinguish between the lightning current and other noise, and a malfunction does not easily occur. Further, it is not necessary to use a common ground for the communication line and the commercial power supply line, and it is not necessary to use an insulating transformer.

According to a third aspect of the present invention, in the lightning damage protection device according to the second aspect, an integration circuit is provided in the lightning current detection circuit.
The comparison circuit compares a signal output from the integration circuit with the threshold value.

By using the integration circuit, malfunction can be prevented in response to high-frequency noise and high-frequency signals other than the lightning current. Further, the switch circuit can be cut off only when it is necessary to actually protect the communication device from lightning current.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Lightning fault protection device 20 of the embodiment
Will be described with reference to FIGS. This form corresponds to all claims.

FIG. 1 is a block diagram showing the configuration of a lightning fault protection device 20 of this embodiment. FIG. 2 shows the lightning fault protection device 20.
FIG. 3 is an electric circuit diagram showing a configuration of a circuit for measuring characteristics of the integrating circuit 22 of FIG. FIG. 3 shows the integration circuit 2 of the lightning fault protection device 20.
6 is a graph showing the characteristic measurement results of Example 2. In this form,
The lightning current detection circuit, the comparison circuit, and the switch circuit according to claim 2 correspond to the current transformer 21, the comparator 23, and the relay 24, respectively, and the integration circuit according to claim 3 corresponds to the integration circuit 22.

Referring to FIG. 1, a communication line 51 and a commercial power line 52 are connected to a communication line connection terminal 11 and a commercial power line connection terminal 12 of a communication device 10, respectively. In this example, a lightning fault protection device 20 is inserted between the communication line connection terminal 11 and the communication line 51. The lightning fault protection device 20 includes a current transformer 21, an integration circuit 22, and a comparator 23.
And a relay 24. The comparator 23
Is connected to a threshold adjuster 25.

Since the electrical contacts of the relay 24 are normally closed, the communication line 51 is normally connected to the communication line connection terminal 11 of the communication device 10. When a lightning current generated by a lightning strike or the like appears on the communication line 51, a voltage V is applied to the secondary winding of the current transformer 21 by the lightning current flowing through the primary winding of the current transformer 21.
1 is induced. This voltage V1 is applied to the integration circuit 22.

In this example, the integrating circuit 22 comprises a resistor R1 and a capacitor C1. The integrated output voltage Vc output by the integration circuit 22 is a voltage between terminals of the capacitor C1. Comparator 23 compares the level of the threshold voltage adjusted in advance by threshold adjuster 25 with the level of integrated output voltage Vc, and outputs a binary signal indicating the result.

The relay 24 is turned on / off by the binary signal output from the comparator 23. That is, when the integrated output voltage Vc exceeds the threshold value, the drive coil built in the relay 24 is energized, and the electrical contact of the relay 24 opens. Thereby, the communication line connection terminal 11 and the communication line 51 are connected.
Are physically shut off. Since the lightning fault protection device 20 detects the current waveform of the lightning current appearing on the communication line 51 by smoothing it with an integrating circuit, it has a feature that it does not malfunction in response to a high-frequency current or induction noise appearing on the communication line 51.

That is, by integrating the voltage V1 appearing on the secondary winding of the current transformer 21 by the integration circuit 22, an integrated output voltage Vc proportional to the peak level of the lightning current is obtained. The integrated output voltage Vc is almost zero for a high-frequency current or induction noise that normally appears on the communication line 51.
Only when the peak value of the lightning current waveform exceeds the threshold value set in the comparator 23, the relay 24 operates to physically disconnect the communication line connection terminal 11 from the communication line 51.

Since the electric charge accumulated in the capacitor C1 of the integrating circuit 22 is discharged through the resistor R1 and the secondary winding of the current transformer 21, when the lightning current no longer appears on the communication line 51, the integrated output is obtained. Voltage Vc gradually decreases. Then, the electric contact of the relay 24 is automatically closed as time passes, so that the cutoff state is released.

Using the circuit shown in FIG. 2A, the characteristics of the integration circuit 22 shown in FIG. 1 were measured by simulation.
FIG. 3 shows a measurement result when the resistance value of the resistor R1 is 10 KΩ. In the circuit of FIG. 2A, a lightning surge generating circuit 30 is used to generate the voltage V1. This lightning surge generating circuit 30 has a voltage V having a waveform as shown in FIG.
Generates 1. Specifically, the peak level of the voltage V1 is about 100 [V], the rise time is 0.1 [μs], and the fall time is 40 [μs]. This simulates a state corresponding to a lightning current of about 60 [A] flowing.

Based on the characteristics shown in FIG.
If the capacitance of 1 is set to 0.11 [μF], an integrated output voltage Vc of about 3 [V] with respect to the voltage V1 of FIG. 2 can be obtained. In that case, if the threshold level of the comparator 23 is set to a level slightly lower than 3 [V], the relay 24 is controlled when a lightning current of about 60 [A] is detected, and the communication line 51 is connected to the communication line. It can be disconnected from the connection terminal 11.

In practice, by adjusting the threshold level of the comparator 23 in consideration of the withstand voltage of the communication device 10, the communication device 10 is reliably protected from a failure due to a lightning current. Since the communication line 51 is physically separated from the communication line connection terminal 11 using the relay 24, the lightning current that has entered through the communication line 51 does not leak to the commercial power supply line 52 side.

The lightning fault protection device 20 shown in FIG. 1 was actually manufactured as a trial and an experiment was carried out. As a result, the same result as the simulation was obtained. That is, according to the method and apparatus of the present invention,
It was confirmed that the communication line side could be physically disconnected when a lightning current occurred, and that overvoltage was not applied to the communication device side, and protection from lightning failure was possible. In the lightning fault protection device 20 shown in FIG. 1, the case where the electrical contact uses one relay 24 to control the interruption of the single communication line 51 has been described. In this case, a relay having a plurality of electrical contacts may be used in place of the relay 24 to simultaneously cut off the respective signal lines.

Further, in the lightning fault protection device 20 shown in FIG.
However, a non-contact current probe may be used instead of the current transformer 21. In the embodiment shown in FIG. 1, the lightning failure protection device 20 is provided between the communication line 51 and the communication line connection terminal 11.
Is shown, the lightning fault protection device 20 may be inserted between the commercial power supply line 52 and the commercial power supply line connection terminal 12, or one of the two lightning fault protection devices 20 may be used. The lightning fault protection device 20 may be connected as shown in FIG. 1 and the other lightning fault protection device 20 may be inserted between the commercial power line 52 and the commercial power line connection terminal 12.

[0028]

As described above, according to the lightning fault protection method according to the first aspect, since the lightning current is detected and cut off, the lightning current flowing from the communication line to the commercial power supply line or the commercial power supply line is detected. This prevents lightning currents from flowing into the communication line, thereby realizing highly reliable lightning protection for communication equipment.

Further, according to the lightning fault protection device of the second aspect, the device achieving the effect of the first aspect can be realized at low cost, which is extremely effective for practical use. Furthermore, according to the lightning fault protection device of the third aspect, the integration circuit is provided, so that the lightning current and other noises are distinguished from each other, thereby preventing malfunction from occurring.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a lightning fault protection device 20 according to an embodiment.

FIG. 2 is an electric circuit diagram showing a configuration of a circuit for measuring characteristics of an integration circuit 22 of the lightning fault protection device 20.

FIG. 3 is a graph showing characteristics measurement results of the integration circuit 22 of the lightning fault protection device 20.

FIG. 4 is a block diagram showing a configuration of a conventional lightning protection technology.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Communication equipment 11 Communication line connection terminal 12 Commercial power line connection terminal 20 Lightning fault protection device 21 Current transformer 22 Integration circuit 23 Comparator 24 Relay 25 Threshold adjuster 30 Lightning surge generation circuit 51 Communication line 52 Commercial power line R0, R1 resistance C1 capacitor V1 voltage Vc integral output voltage

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[Procedure amendment]

[Submission date] September 9, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 2

[Correction method] Change

[Correction contents]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

According to a first aspect of the present invention, there is provided a lightning protection method for a communication device to which a communication line and a commercial power supply line are connected. A lightning current or a lightning voltage entering the communication device is detected on both of the power supply lines, and the detected lightning current or the lightning voltage is determined in advance by taking into account the overvoltage tolerance or the overcurrent tolerance of the communication device. When the detected lightning current or lightning voltage exceeds the threshold, at least one of the communication line and the commercial power line is physically disconnected from the communication device using a predetermined circuit breaker. It is characterized by the following.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

According to the present invention, when a lightning current or a lightning voltage exceeding a threshold enters a communication device, at least one of the communication line and the commercial power line is physically disconnected from the communication device by the circuit breaker. Therefore, the communication device can be reliably protected from the lightning current appearing on the communication line or the commercial power line. A lightning damage protection device according to claim 2 is a lightning protection device for a communication device to which a communication line and a commercial power line are connected, wherein the communication device is connected to the communication device from both the communication line and the commercial power line connected to the communication device. A lightning current detection circuit that detects a signal corresponding to the level and waveform of the intruding lightning current, and a signal detected by the lightning current detection circuit is determined in advance in consideration of the overvoltage tolerance or the overcurrent tolerance of the communication device. A comparison circuit for comparing with a threshold value, and a switch circuit for disconnecting at least one of a communication line and a commercial power line connected to the communication device from the communication device according to a comparison result of the comparison circuit. And

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toru Kishimoto Nippon Telegraph and Telephone Corporation 3-9-1-2 Nishishinjuku, Shinjuku-ku, Tokyo (72) Inventor Hiroo Nose 3-192-1, Nishishinjuku, Shinjuku-ku, Tokyo No. Within Nippon Telegraph and Telephone Corporation (72) Inventor Takahiro Kobayashi Within Nippon Telegraph and Telephone Corporation

Claims (3)

[Claims] A lightning protection method for a communication device to which a communication line and a commercial power supply line are connected, wherein a lightning current or at least one of a communication line and a commercial power supply line connected to the communication device enters the communication device. Detecting a lightning voltage, comparing the detected lightning current or lightning voltage with a predetermined threshold value in consideration of the overvoltage tolerance or overcurrent tolerance of the communication device, and determining whether the detected lightning current or lightning voltage is When the threshold value is exceeded, at least one of the communication line and the commercial power line is physically separated from the communication device using a predetermined circuit breaker. 2. A lightning protection device for a communication device to which a communication line and a commercial power supply line are connected, wherein a lightning current of at least one of the communication line and the commercial power supply line connected to the communication device is transmitted to the communication device. A lightning current detection circuit for detecting a signal corresponding to a level and a waveform, and comparing the signal detected by the lightning current detection circuit with a predetermined threshold value in consideration of an overvoltage tolerance or an overcurrent tolerance of the communication device. A lightning fault, comprising: a comparison circuit; and a switch circuit that disconnects at least one of a communication line and a commercial power line connected to the communication device from the communication device according to a comparison result of the comparison circuit. Protective equipment. 3. The lightning damage protection device according to claim 2, wherein an integration circuit is provided in the lightning current detection circuit, and the comparison circuit compares a signal output from the integration circuit with the threshold value. And lightning damage protection device.