JPH0595623A - Surge protection network system - Google Patents

Abstract

PURPOSE:To realize a surge protection network system, in which a destruction and malfunction due to external surge current can be prevented whether a safety/communication earth terminal is connected with a ground earth or not. CONSTITUTION:The frame/signal earth ER2 in a communication terminal apparatus is completely separated from an external surge current route SG. Thus, it is possible to prevent the destruction of the apparatus and the malfunction in the apparatus caused by external surge current. Also, a triode lightning arrester 21 being a surge protection element is inserted between a safety/ communication earth terminal E and the external surge current route SG. As a result, a satisfactory surge protection function can be obtained whether the safety/communication earth terminal E is connected with the ground or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surge protection circuit system for a communication terminal device that uses a commercial power source to realize a telecommunication function by connecting to a wired telecommunication line.

[0002]

2. Description of the Related Art In a communication terminal device that uses a commercial power source, a lightning surge or the like that comes in through an overhead line for a commercial power source or an overhead line for a communication line, or a surge that enters through other devices that use a commercial power source. It is indispensable to protect from damage caused by static AC noise, electrostatic noise applied and discharged through the human body, and malfunction of devices. This is because these surge noises are
Or, it is easy to mix in the same phase (common mode) between the ground and the communication line, and the mixed noise on the one hand through the equipment internal circuit on the other ground ground, that is, the pole transformer ground for the commercial power line, This is because a communication line is likely to have a current surge flowing toward the communication ground at the other end, and therefore, these types of terminal equipment require more consideration for surge protection than other types of electronic equipment. .. Furthermore, in the case of a device using a communication line, a communication earth may be connected to the ground for communication, and from this viewpoint, consideration of surge protection is important.

A general surge protection circuit system for dealing with the above-mentioned surge protection has conventionally been as shown in FIG.

In FIG. 2, a commercial power supply line is connected to a ground power source ER1 (for example, AC100).
V) closing switch 2 and fuse 3 for inputting 1
The commercial power supply is supplied to the DC power supply circuit 4 via the closing switch 2 and the fuse 3. The DC power supply circuit 4 converts a commercial power supply into a DC voltage source required inside the equipment. A communication line interface circuit 5 for realizing a communication function is connected to the communication line 6 equivalently shown in FIG. The communication line 6 is connected to the earth ER1 via the communication terminal device on the other side. Note that the output voltage from the DC power supply circuit 4 and the circuit inside the device (for example, the communication line interface circuit 5) are
Frame / Signal earth ER connected to the equipment housing
The standard is 2.

The communication terminal equipment is provided with a security / communication ground terminal E, and the earth / ground ER1 and the frame / signal ground ER2 can be connected via the security / communication ground terminal E.

The communication terminal equipment connected to the commercial power source 1 and the communication line 6 in this way is, for the above-mentioned reason,
A surge absorption / discharge circuit 10 as a surge protection structure is provided. The surge absorbing / discharging circuit 10 includes three-pole surge arresters 11 and 4
It is composed of individual varistors 12 to 15. Both poles of the three-pole surge arrester 11 are connected to each commercial power supply line via a varistor 12 or 13, respectively. 3 pole arrester 1
The grid No. 1 is connected to each communication line via varistor 14 and 15. The three-pole surge arrester 11 discharges when the voltage between both electrodes exceeds a predetermined voltage value due to an external surge or the like, or when the voltage between one pole and the grid exceeds a predetermined voltage value due to an external surge or the like. When the voltage becomes equal to or lower than a predetermined voltage value due to such discharge, the discharge is stopped and the current path is cut off. Barista 12
Numerals 13 and 13 are for preventing the discharge from continuing due to the continuous flow of the commercial power source, and varistors 14 and 15 are for absorbing the surge from the communication line 6 above a certain value.

The connection line SG between the grid of the three-pole arrester 11 and the communication line side varistors 14 and 15 is a current route through which an external surge current flows, as will be described later. It is connected to the signal ground ER2 and thus to the security / communication ground terminal E.

Basic surge absorption in the above configuration,
The principle of discharge is as follows. That is, the external surge mixed in the same phase with the ground in the commercial power supply line is communicated through the varistor 12, 13 on the commercial power supply side, the three-pole arrester 11, and the varistor 14, 15 on the communication line side in this order. Line 6
It is absorbed as an external surge current toward the earth ground ER1. In addition, an external surge mixed in the same phase with the ground on the communication line is the varistor 14 on the communication line side.
15, a three-pole surge arrester 11, and a varistor 1 on the commercial power supply side
Earth ground ER1 of commercial power supply 1 through 2 and 13 in order
Is absorbed as a surge current toward. Therefore, the line SG serves as a current route for passing the external surge current.

With respect to the external surge mixed in the normal mode between the commercial power supply lines or the communication line, the varistor 12, 13 on the commercial power supply side or the three-pole surge arrester 1 is used.
It goes without saying that it is absorbed and discharged by the varistor 14 and 15 on the communication line side.

As the surge absorbing / discharging circuit, in addition to the circuit 10 shown in FIG. 2, various circuits similar thereto have been conventionally used. That is, the three-pole arrester 11 in FIG.
Is replaced with a varistor pair, two bipolar discharge tubes connected in series, the varistor 14 on the communication line side in FIG.
The one in which 15 is replaced with one three-pole surge arrester has been proposed. These all act on external surges in the same manner as those shown in FIG. 2 and obtain similar effects.

[0011]

However, in the above-mentioned conventional method, in the state where the safety / communication earth terminal E is connected to the earth ground, the operation stability against the external surge mixed in the same phase with the earth is established. There was a problem.

Usually, as shown in FIG. 2, the current route SG of the external surge current is the frame / signal earth ER of the equipment.
Since it is connected to 2, the surge current will flow through the frame / signal earth ER2 against the external surge that is mixed with the ground in the same phase, which will affect the stability of the internal operation of the equipment. May affect. In order to avoid this, an attempt has been made to separate the current route SG of the external surge from the signal ground inside the equipment and make it an independent wiring, but in large-scale communication terminal equipment, the signal ground wire is complicated, and in addition, it is small. In a communication terminal device, independent wiring may be difficult, so that good results may not be obtained as long as it is connected to the same potential as the signal ground line. Therefore, a configuration may be considered in which the route SG of the external surge current is completely separated from the signal ground, but in this case, when the communication / safety ground terminal E is connected to the ground, it is mixed in the same phase with the ground. The potential of the external surge current route SG during the discharge of the external surge is a value obtained by subtracting the voltage value at the time of discharging the varistor 12 and 13 from the communication / safety earth terminal E, which is still a large potential. There is a possibility of causing dielectric breakdown between the line SG and the security / communication ground terminal E, inside the DC power supply circuit 4, or inside the communication line interface circuit 5.

The above problems are as described above.
Even when the three-pole arrester 11 in FIG. 2 is replaced with a varistor pair or the like, or when the communication line side varistors 14 and 15 are replaced with three-pole arrester or the like, the same drawback occurs.

The present invention has been made in consideration of the above points, and can prevent damage or malfunction due to an external surge current regardless of whether or not the safety / communication ground terminal is connected to the ground. It is intended to provide a surge protection circuit system.

[0015]

In order to solve such a problem, the present invention provides a surge protection circuit system for a communication terminal device using a commercial power source, which is an external circuit when an external surge enters the commercial power line. An external surge current is sent to the earth ground on the communication line side via the surge current route, and when an external surge enters the communication line side, an external surge current is sent to the earth ground on the commercial power source side via the above external surge current route. In the surge protection circuit system in which the current is flowed, the frame / signal ground inside the communication terminal device is completely separated from the external surge current route, and the frame / signal ground can be connected to the earth ground. It was decided to insert a surge protection element between the ground terminal and the above-mentioned external surge current route.

[0016]

In the present invention, the frame / signal ground inside the communication terminal equipment is connected from the commercial power line to the communication line, or from the communication line to the commercial power line.
By completely separating the external surge current route through which the external surge current flows and the frame / signal ground inside the communication terminal device, it is possible to prevent the device from being damaged due to the external surge current and the internal malfunction of the device. Further, in the present invention, by inserting a surge protection element such as a lightning arrester between the security / communication ground terminal capable of connecting the frame / signal ground to the ground earth and the external surge current route, the security / communication ground terminal is provided. Whether or not you connect the
A good surge protection function can be realized.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIG. Here, FIG. 1 is a block diagram showing the configuration of this embodiment.

In the case of this embodiment, as shown in FIG. 1 in which the same parts as those in FIG.
Unlike the conventional configuration of the discharge circuit 20, the connection configuration with the commercial power supply 1 of the communication terminal device and the connection configuration with the communication line 6 are as follows.
Naturally, it is the same as the conventional one. That is, the commercial power source 1 is connected to the DC power source circuit 4 through the switch 2 and the fuse 3 for turning on.
The communication line 6 is connected to the communication terminal equipment by the communication line interface circuit 5.

The surge absorbing / discharging circuit 20 of this embodiment
Also, it is composed of a triode arrester 21 and four varistors 22 to 25. However, the connection method is different from the conventional one. One pole of the three-pole surge arrester 21 is connected to the other ends of the varistors 22 and 23 whose one end is connected to one commercial power supply line. The other pole of the three-pole surge arrester 21 is connected to a frame / signal earth ER2, which is connected to a security / communication earth terminal E which can be connected to a ground earth ER1. The grid of the three-pole surge arrester 21 is connected to each communication line via the current route SG of the surge current and further via the varistors 24 and 25.

Therefore, the current route SG of the surge current is
It is completely separate from the frame / signal earth ER2. In this embodiment, the current route SG of such a surge current is completely separated and independent from the frame / signal ground ER2, and as described above, the frame / signal ground ER2 (hence, the security / communication ground terminal E) is used. ) And the external surge current route SG, a three-pole surge arrester 21 is inserted.

The above-mentioned triode arrester 21 of this embodiment is also
Discharge is performed when the voltage between both poles exceeds a predetermined voltage value due to an external surge or when the voltage between one pole and the grid exceeds a predetermined voltage value due to an external surge. The discharge is stopped and the current path is cut off when the voltage becomes equal to or lower than a predetermined voltage value. Also, the varistors 22 and 23 are for preventing the discharge from continuing due to the continuous flow of the commercial power source, and the varistors 24 and 25 are for absorbing the surge from the communication line 6 which is equal to or more than a certain value.

In the above-mentioned structure, the external surge mixed in the commercial power supply line in the same phase with the ground also communicates with the varistor 22 and 23 on the commercial power supply side, the three-pole arrester 21, in this embodiment as well. A surge current is absorbed toward the ground earth ER1 of the communication line 6 through the line-side varistor 24 and 25 in order and is absorbed. In addition, an external surge mixed in the same phase with the ground on the communication line is also commercialized via the varistor 24, 25 on the communication line side, the three-pole arrester 21, and the varistor 22, 23 on the commercial power source side in this order. It is absorbed as a surge current toward the ground earth ER1 of the power supply 1.

Therefore, according to the above-mentioned embodiment, since the external surge current route SG is completely separated from the frame / signal earth ER2 connected to the security / communication ground terminal E, the security / communication ground terminal E is provided. Earth Earth ER
Whether or not 1 is connected, the surge current does not affect the stability of the internal operation of the device via the frame / signal earth ER2. Further, even when the safety / communication ground terminal E is connected to the ground earth ER1, it is possible to surely absorb the surge by the discharge of the three-pole surge arrester 21 against an external surge mixed with the ground in the same phase. it can.

Incidentally, in the past, when trying to obtain the same effect, the whole structure was complicated and expensive, but in the case of this embodiment, the three poles which existed in the past are also present. The effects described above can be obtained only by changing the connection of various lines to the lightning arrester 21, and the overall circuit simplification and cost reduction can be realized.

Note that, instead of the three-pole surge arrester 21 in FIG. 1, two two-pole discharge tubes may be connected in series, and a pair of varistor and the like may be arranged in the same manner to obtain the same effect. be able to.

[0026]

As described above, according to the present invention, the frame / signal ground inside the communication terminal equipment is completely separated from the external surge current route, and the safety / communication ground terminal and the external surge current route are connected. Since a surge protection element is inserted between them, it is possible to prevent damage to the equipment due to external surge current, malfunctions inside the equipment, etc. In addition, a good surge protection function is provided regardless of whether the safety / communication ground terminal is connected to the ground. Obtainable.

[Brief description of drawings]

FIG. 1 is a block diagram showing a surge protection circuit system of an embodiment.

FIG. 2 is a block diagram showing a conventional surge protection circuit system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Commercial power supply, 6 ... Communication line, 20 ... Surge absorption / discharge circuit, 21 ... Tripole arrester, 22-25 ... Varistor, ER
1 ... Earth ground, ER2 ... Frame / signal ground, E ...
Security / communication ground terminal, SG ... External surge current route.

Claims (1)

[Claims] 1. A surge protection circuit system for a communication terminal device using a commercial power supply, wherein when an external surge is mixed into a commercial power supply line, the external surge current is supplied to the earth ground of the communication line side via an external surge current route. In the surge protection circuit method in which the external surge current flows to the earth ground of the commercial power source side via the external surge current route when the external surge enters the communication line side, The frame / signal ground of is completely separated from the external surge current route, and a surge protection element is inserted between the security / communication ground terminal capable of connecting the frame / signal ground to the ground and the external surge current route. Surge protection circuit method that is characterized.