JP2000076984A - Breaker circuit for protection against lightning failures - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve, at relatively low cost, a high reliability of protection against lightning failures of a breaker circuit for protection against failures due to lightning and to protect communication equipment itself and information retained therein from lightning. SOLUTION: This circuit is provided with a switching means 30 placed in a part of at least either a communications line or commercial power line, a lightning current detection means 21 for producing signals corresponding to lightning currents entering communications equipment from the communications line or commercial power line, an integrating circuit 22 for integrating the signals generated by the means 21, a rectifying circuit 24 for rectifying the signals outputted by the circuit 22, and a control means, which when the level of the signal outputted by the rectifying circuit 24 exceeds a predetermined level, controls the switching means 30 for separating at least either the communications line or commercial power line from the communications equipment.

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. Circuit breaker circuit for lightning damage protection.

[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. Not only networks provided by telecommunications carriers but also user-based services such as corporate LANs and homes have been developed. 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 communication device breaks down the circuit inside the communication device and moves to the opposite side of the intrusion route. 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. 3A 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. 3B 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.

FIGS. 3C and 3D 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. By the way, many recent communication devices hold various information in a built-in memory. Further, when a power failure or the like occurs at the time of lightning damage, the information held in the memory of the communication device is often erased or destroyed. Therefore, regarding the effects of lightning, not only the failure of the communication equipment itself but also the destruction of the information held therein becomes an important problem.

[0008] In order to prevent information from being destroyed by a power failure, communication devices have conventionally been equipped with a backup power supply such as a storage battery. Then, when a power failure occurs, the commercial power supply is automatically switched to the backup power supply. Therefore, even if a power failure occurs, power supply to the communication device is continued for a certain period of time, and destruction of information is prevented.
By the way, many recent communication devices hold various information in a built-in memory. Further, when a power failure or the like occurs at the time of lightning damage, the information held in the memory of the communication device is often erased or destroyed. Therefore, regarding the effects of lightning, not only the failure of the communication equipment itself but also the destruction of the information held therein becomes an important problem.

In order to prevent information from being destroyed by a power failure, communication equipment has conventionally been equipped with a backup power supply such as a storage battery. Then, when a power failure occurs, the commercial power supply is automatically switched to the backup power supply. Therefore, even if a power failure occurs, power supply to the communication device is continued for a certain period of time, and destruction of information is prevented.

[0010]

In the case where the above-mentioned bypass arrester method is used to protect communication equipment by lightning, a current intruding from a communication line or a commercial power supply line when a lightning strike occurs may flow through the bypass arrester. However, a potential difference is naturally generated between the communication line and the commercial power supply line, and it is essentially unavoidable that a voltage is applied to the device to near the breakdown voltage of the device.

[0011] Further, if the above-mentioned common grounding method is applied to communication equipment used in an existing house, a high cost is required due to the necessity of repair work on the house. 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.

Further, even if a backup power supply is installed to prevent the destruction of stored information at the time of a power failure, the information held inside the communication device is destroyed by the effect of a lightning strike before the power failure occurs. May be done. Therefore, the information stored in the communication device cannot be protected from lightning only by mounting the backup power supply. SUMMARY OF THE INVENTION It is an object of the present invention to provide a circuit breaker circuit for protection against lightning damage, which realizes high reliability of protection against lightning damage at relatively low cost, and protects the communication equipment itself and information held therein from lightning. .

[0013]

According to a first aspect of the present invention, there is provided a circuit breaker circuit for protection against lightning damage of a communication device to which a communication line and a commercial power line are connected, wherein at least one of the communication line and the commercial power line connected to the communication device is provided. A switch disposed at one halfway thereof; a lightning current detecting unit configured to generate a signal corresponding to a lightning current entering the communication device from at least one of the communication line and the commercial power line; An integrating circuit for integrating the obtained signal, a rectifying circuit for rectifying the signal output by the integrating circuit, and controlling the switch means when the level of the signal output by the rectifying circuit exceeds a predetermined level; A control unit for automatically disconnecting at least one of the communication line and the commercial power line from the communication device is provided.

When a lightning current appears on the communication line or the commercial power line, a signal corresponding to the current is output from the lightning current detection means. The signal output from the lightning current detection means is integrated by the integration circuit and rectified to a specific polarity by the rectification circuit. The control means controls the switch means when the level of the signal output from the rectifier circuit exceeds a predetermined level.
Therefore, the switch means automatically disconnects at least one of the communication line and the commercial power line from the communication device when a lightning current is detected.

Therefore, according to the first aspect, it is possible to protect the communication device by reliably shutting off the lightning current before the lightning current entering the communication device exceeds the withstand voltage of the communication device. In addition, since expensive equipment such as an insulation transformer and special installation work are not required, communication equipment can be protected at low cost. Claim 2
Is a circuit breaker circuit for protection against lightning damage according to claim 1.
A dual-wave rectifier circuit is used as the rectifier circuit.

The polarity of the signal output from the lightning current detecting means due to the occurrence of the lightning current may be positive or negative. Also, this polarity may change depending on the installation condition of the breaker circuit for lightning damage protection. According to claim 2, by using the dual-wave rectifier circuit,
Regardless of whether the polarity of the signal output by the lightning current detection means is positive or negative, a signal having a predetermined polarity is obtained, and in any case, the lightning current is detected. In this case, at least one of the communication line and the commercial power line can be reliably disconnected from the communication device.

According to a third aspect of the present invention, in the circuit breaker circuit for protecting against lightning damage according to the first aspect, a pulse generating circuit for generating a pulse signal having a predetermined width when a level of a signal output from the rectifier circuit exceeds a predetermined level. Is provided in the control means. Since the time during which a lightning current actually appears is very short, communication devices can be protected by shutting off only when a large level lightning current is detected. According to the third aspect, the pulse generation circuit generates a pulse signal having a predetermined width when the level of the signal output from the rectifier circuit exceeds a predetermined level. Can be. Therefore, even when the switch means operates to cut off the lightning current, the state returns automatically to the original state after a lapse of a predetermined time. That is, there is no need for a human to perform a manual operation to release the cutoff state.

[0018]

1 and 2 show an embodiment of a circuit breaker circuit for protection against lightning damage according to the present invention. This form corresponds to all claims. FIG. 1 is a block diagram showing the configuration of a circuit breaker circuit for lightning damage protection of this embodiment. FIG. 2 is a time chart showing the operation of the circuit breaker circuit for lightning damage protection of this embodiment.

In this embodiment, the switch means of the first aspect,
The lightning current detecting means, the integrating circuit, and the rectifying circuit correspond to the relay 30, the zero-phase current transformer 21, the integrating circuit 22, and the bridge rectifying circuit 24, respectively. This corresponds to the pulse generator 29. In addition, the double-wave rectification circuit of claim 2 corresponds to the bridge rectification circuit 24, and the pulse generation circuit of claim 3 corresponds to the pulse generator 29.

As shown in FIG. 1, a communication device 1 to be protected is provided.
0 is connected to the communication line 51 via the communication line terminal 11,
It is connected to the commercial power line 52 via the power line terminal 12. In this example, a breaker circuit 20 for protection against lightning damage is inserted between the communication line 51 and the commercial power line 52. Circuit breaker circuit 2 for protection against lightning damage shown in FIG.
0 is a zero-phase current transformer 21, an integrating circuit 22, a varistor 23,
Bridge rectifier circuit 24, capacitor 25, Zener diode 26, resistor 27, battery 28, pulse generator 29
And a relay 30. Battery 28 is a power supply for supplying power to pulse generator 29.

When a lightning surge current caused by a lightning strike or the like flows through the commercial power supply line 52, a signal (voltage V0) proportional to the magnitude of the lightning surge current is output from the zero-phase current transformer 21. The signal output from the zero-phase current transformer 21 is input to an integrating circuit 22 composed of a resistor R1 and a capacitor C1.

At the output of the integrating circuit 22, a signal (voltage Vc) integrated with a time constant determined by the resistor R1 and the capacitor C1 is obtained. The varistor 23 protects the lightning damage protection breaker circuit 20 itself when an excessive surge voltage appears as the voltage Vc. The bridge rectifier circuit 24 outputs a unipolar signal regardless of the polarity of the voltage Vc of the input signal. That is, assuming that the terminal 24b is at the ground potential, a voltage having a positive polarity always appears at the terminal 24a.

The polarity of the voltage V0 of the signal output from the zero-phase current transformer 21 changes due to the difference in the direction of the lightning surge current flowing through the commercial power line 52 and the difference in the direction in which the breaker circuit 20 for protection against lightning damage is attached. However, by using the bridge rectifier circuit 24, a signal having a constant polarity is always obtained between the terminals 24a and 24b. Zener diode 26
Is provided to determine a threshold value for binaryly identifying the level of the lightning surge current. That is, since the breakdown voltage of the Zener diode 26 hardly changes, this breakdown voltage is used to determine the threshold voltage.

The output terminals 24a of the bridge rectifier circuit 24,
If the voltage appearing between 24b is less than the breakdown voltage of the Zener diode 26, no current flows through the Zener diode 26 and the resistor 27 and the voltage V1 between the terminals of the resistor 27
Becomes 0. Lightning surge current appears and bridge rectifier circuit 2
When the voltage appearing between the output terminals 24a and 24b of the No. 4 is equal to or higher than the breakdown voltage of the Zener diode 26, a current flows through the Zener diode 26 and the resistor 27, and a positive voltage V1 appears between the terminals of the resistor 27.

The voltage V 1 between the terminals of the resistor 27 is applied to the input of the pulse generator 29. The pulse generator 29 is constituted by a monostable multivibrator circuit in this example. The pulse generator 29 has a built-in driver necessary for driving the drive coil 31 of the relay 30. When the voltage V1 input to the pulse generator 29 is 0 [V], no pulse is generated, and no current flows through the drive coil 31, so that the electric contact 32 and the communication line 51 arranged on the commercial power supply line 52 Are closed.

When a lightning surge current appears and the voltage V1 input to the pulse generator 29 increases to some extent, the pulse generator 29 is triggered, and a pulse signal having a time width of Ta is generated. This pulse signal is applied to the drive coil 31 as a voltage V2. Accordingly, during the time Ta, the voltage V2 is applied to the drive coil 31, and during that time, the electrical contacts 32 and 33 are opened.

That is, when the lightning surge current is detected, the electric contacts 32 and 33 are opened only for the time Ta as shown in FIG. Therefore, the communication device 10 is protected from the lightning surge current. Further, when the time Ta elapses after the electric contacts 32 and 33 are opened, the electric contacts 32 and 3 are opened.
3 automatically closes, it is not necessary to manually release the cut-off state of the breaker circuit 20 for protection against lightning damage.

Although FIG. 2 shows only the case where the voltage Vc has a positive polarity, even when the voltage Vc has a negative polarity, the polarity of the voltage V1 is kept constant by the rectifying function of the bridge rectifier circuit 24. Since it is maintained, the pulse generator 29 can be triggered by the voltage V1. In this example, the communication line 51 and the commercial power line 52
The breaker circuit 20 for protection against lightning damage is connected so as to shut off both the communication line 51 and the commercial power line 52.
The lightning damage protection circuit breaker circuit 20 may be connected to only one of them. Further, the zero-phase current transformer 21 may be arranged in the communication line 51 instead of the commercial power line 52.

The lightning damage protection circuit breaker circuit 20 shown in FIG. 1 was actually manufactured as a prototype, and a lightning surge current of about 60 [A] intruded only into the communication line 51 and into the commercial power line 52 only. The experiment was performed by adjusting the constants of the circuit so that the relay 30 was operated in each of the case and the case where both the communication line 51 and the commercial power line 52 were intruded. That is, when a simulated current waveform for obtaining the lightning surge current is generated by using a test pulse generator, and this lightning surge current is applied to the communication line 51, the lightning damage protection circuit breaker circuit 20 is activated and the relay circuit is activated. It was confirmed that the communication line 51 was cut off by the electrical contacts 33 of the communication device 30 and the communication device 10 was protected.

Further, in the trial production of the circuit, it was confirmed that the breaker circuit 20 for protection against lightning damage can be constituted by only commercially available inexpensive components. Therefore, a low-cost lightning damage protection circuit breaker circuit 20 can be provided.

[0031]

As described above, the use of the circuit breaker circuit for protection against lightning damage according to the first aspect of the present invention realizes high reliability of protection against lightning damage of communication equipment. In addition, an inexpensive lightning damage protection circuit breaker circuit can be provided.

In particular, according to the present invention, the level can be identified and the circuit can be cut off irrespective of the polarity of the lightning surge current to be detected. There is no need to consider the direction and polarity of
Further, since it is not necessary to provide a circuit for identifying the level of the lightning surge current for each polarity of the signal, the circuit configuration is simplified and the cost is reduced. Further, according to the third aspect, since the cutoff state can be automatically released as time passes, a manual release operation is not required.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a breaker circuit for lightning damage protection according to an embodiment.

FIG. 2 is a time chart illustrating an operation of the circuit breaker circuit for lightning damage protection according to the embodiment;

FIG. 3 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 terminal 12 Power supply line terminal 20 Breaker circuit for lightning damage protection 21 Zero-phase current transformer 22 Integrator circuit 23 Varistor 24 Bridge rectifier circuit 25 Capacitor 26 Zener diode 27 Resistor 28 Battery 29 Pulse generator 30 Relay 31 drive coil 32,33 electrical contact 51 communication line 52 commercial power line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Eiji Ohashi, Inventor 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Inside Japan Telegraph and Telephone Corporation (72) Inventor Kazuo Murakawa 3-192-1, Nishishinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation F-term (reference) 5G030 AC00 XX18 YY12 YY14

Claims (3)

[Claims] In a circuit breaker circuit for protection against lightning damage of a communication device to which a communication line and a commercial power line are connected, a switch means disposed at least halfway between at least one of the communication line and the commercial power line connected to the communication device. A lightning current detection unit that generates a signal corresponding to a lightning current that enters the communication device from at least one of the communication line and the commercial power line, and an integration circuit that integrates the signal generated by the lightning current detection unit. A rectifier circuit for rectifying the signal output by the integration circuit; and controlling the switch means when the level of the signal output by the rectifier circuit exceeds a predetermined level, to control at least the communication line and the commercial power line. A circuit for automatically disconnecting one of the communication devices from the communication device; 2. The lightning damage protection circuit breaker circuit according to claim 1, wherein a double-wave rectifier circuit is used as said rectifier circuit. 3. The circuit breaker circuit according to claim 1, wherein said pulse generator circuit generates a pulse signal having a predetermined width when a level of a signal output from said rectifier circuit exceeds a predetermined level. A circuit breaker circuit for protection against lightning damage, which is provided in the means.