JPS6188722A - Protector for communication - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication protector that protects communication equipment within a switching center from abnormal voltages and abnormal currents generated in communication lines due to lightning strikes, power line crosstalk, or the like.

[Conventional technology]

Conventionally, this type of communication protector has a gas input detonator 42 provided between one internal communication line A-B and CD and a grounding terminal 41, as shown in FIG. The main wiring between the external communication line and the protected communication equipment consists of heat coils 43 provided on the exchange equipment side at the connection points between the pipe 42 and the internal communication lines A-B and CD. The primary protector 4 provided on the board (MDF), the internal communication lines A-B and CD provided in the subscriber circuit (LC) after this primary protector, and the ground terminal 51. and a secondary protector 5 consisting of a metal oxide varistor 52 connected between the two.

The electrical characteristics of each element are that the discharge starting voltage of the gas entry detonator 42 is approximately 400V, and the current capacity of the heating coil 43 is 35V.
0 mA, and the varistor voltage of the gold-maki oxide varistor 52 is about 120 cm, such as when 1 mA is applied.

[Problem that the invention seeks to solve]

In a communication protector composed of such elements, abnormal voltage may be caused by a lightning strike, for example, on the internal communication lines A-B and C-.
When induced by D, the metal oxide varistor 52, which has a low operating voltage and fast response speed, performs a clamping operation, and the communication line A-
The voltage applied to B and C-D is approximately 250V or less, but because the DC resistance of the heating coil 43 is as small as about 4Ω, the voltage required for igniting the gas entry detonator 42 is not reached. . Therefore, the metal oxide varistor 52 must absorb most of the lightning surge energy, and excessive energy application causes problems such as deterioration of the characteristics of the metal oxide varistor 52 and short-circuit failure. Also, connect AC200 to the external communication line.
When power lines such as V are in contact with each other, the metal oxide varistor 52 performs a clamping operation similar to the operation in response to a lightning strike.
If power line contact continues for a long time (approximately 5 seconds or more), the metal oxide varistor 52 will generate abnormal heat, leading to characteristic deterioration, short circuit failure, and burnout. At this time, since the minimum operating current of the heating coil 43 is a large value of about 0.5 A, it has been impossible to prevent characteristic deterioration, short circuit failure, burnout, etc. of the metal oxide varistor 52. In addition, in order to cope with the drop in withstand voltage of communication equipment due to the shift to LSI in recent years, the output voltage of communication protectors also needs to be protected from lower voltages. [Means for solving the problem] The communication protector of the present invention prevents internal communication between the external communication line side connection terminal and the protected communication device side connection terminal. A first protector having a positive characteristic thermistor and a resistive element connected in series to a line, and a gas entry detonator inserted between a connection point between the positive characteristic thermistor and the resistive element and a ground terminal. a second deep care device located after the first protector and having a non-linear resistance element between the internal communication line and the ground terminal; A resistive element and an anode connected in series with the internal communication line are grounded; a first diode connected to the internal communication line and a cathode connected to the power supply terminal; and a third protector having a diode.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, in one embodiment of the present invention, a primary protector 1 is mounted on a main distribution frame (MDF) installed at an interface between an external communication line and a protected communication device, and 2 Secondary and tertiary protectors 2 and 3 are subscriber circuits (
The primary protector 1 and the secondary and tertiary protectors 2 and 3 are connected by wrapping connection means or the like and a cable. A and C are connection terminals on the external communication line side, and B and D are connection terminals on the protected communication equipment side.

The primary protector 1 has a positive characteristic thermistor 11, which is a current limiting element for limiting abnormal current, connected to an internal communication MA-
B and C-D in series, and a gas input detonator 13 that utilizes low-pressure gas discharge is connected between each connection point of the positive characteristic thermistor 11 and the ground terminal 12. Resistance elements 14 are connected to the rear of the connection points of the tubes 13 to facilitate ignition and discharge of the gas entry detonators 13.

The secondary protector 2 is located after the primary protector l and consists of metal oxide varistors 22 connected between the internal communication lines AB and CD and the ground terminal 21, respectively.

The tertiary protector 3 is located after the secondary protector 2, and has a resistance element 31 inserted in series in internal communication lines A-B and CD, an anode connected to a ground terminal 32, and a cathode connected to the ground terminal 32. The first connected to internal communication lines A-B and C-D.
The diode 33 and cathode of are respectively connected to the power supply terminal -VBB3.
4 and a second diode 35 whose 111 poles are connected to internal communication lines A-B and CD, respectively. Resistance element 31 includes diode groups 33 and 3
5 current limit and non-linear resistance element 22 of secondary protector 2
This is to make the clamp operation easier.

Next, the operation of this embodiment will be explained. The electrical characteristics of each element shown in FIG.
The resistance value of the resistance element 31 is 50Ω, the DC resistance value of the positive temperature coefficient thermistor 11 is 10Ω, and the minimum operation 'v7L current for current limiting is 0.3A.

When an abnormal voltage is induced in an external communication line by a lightning strike, the lightning surge voltage is suppressed by the following three protective operations.

When the surge current is 2A or less, this surge current is passed through the positive characteristic thermistor 11. Resistance element 14. The voltage flows through the resistance element 31 and the diode 33 to the ground terminal 32, and the tertiary protector 3 works, and the forward current-forward voltage characteristic of the diode 33 suppresses the sissage voltage to within the equation 7.

When the surge current is about 2A to IOA, the terminal voltage of the metal oxide varistor 22 is higher than the varistor voltage 100V (50V).
The metal oxide varistor 22 performs a clamping operation and the secondary protector 2 operates.

When the surge current is IOA or more, the terminal voltage of the gas entry detonator 13 is the discharge starting voltage of 250 V or more (terminal voltage of the metal oxide varistor 22 + voltage drop due to the resistance element 14).
Therefore, the gas inlet detonator 13 is clamped and the primary protector is activated.

Next, a protective operation when a power line such as AC 200 V comes into contact with an external communication line will be explained.

If the connection current due to cross-contact is 0.3 A or less, this cross-contact current flows through positive temperature coefficient thermistor 11. Resistance element 14° flows through resistance element 31 and diode 33 to ground terminal 32,
No cross-contact current flows to the communication equipment side.

When the cross-contact current is about 0.3 A to 2 people, the resistance value increases rapidly due to self-heating of the PTC thermistor 11, and the cross-contact current is limited to several tens of mA or less.

If the contact current is 2 Å or more, the terminal voltage of the metal oxide varistor 22 becomes equal to or higher than the varistor voltage before the PTC thermistor 11 limits the current, so the contact current flows into the metal oxide varistor 22, damaging the communication equipment. Protect. After the % light is limited by the increase in the resistance value of the PTC thermistor 11, no current flows through the metal oxide varistor 22, and the communication equipment is protected only by the current limiting action of the PTC thermistor 11.

Furthermore, when the contact current exceeds IOA, the terminal voltage applied to the gas entry detonator 12 becomes equal to or greater than the discharge start voltage until the positive temperature coefficient thermistor 11 limits the current, and the gas entry detonator 12 starts discharging. Thereafter, stain light limitation is performed by the positive temperature coefficient thermistor 11. Note that the same effect can be expected even if another nonlinear resistance element such as a Zener diode is used in place of the metal oxide varistor 22 of the secondary protector.

〔Effect of the invention〕

As explained above, the present invention includes a primary protector consisting of a positive characteristic thermistor, a gas entry detonator, and a resistance element, and a secondary protector consisting of a nonlinear resistance element such as a metal oxide varistor or a Zener diode. A communication protector is constructed from a resistive element and a tertiary protector consisting of first and second diodes, and a relatively large energy burden is placed on the primary protector.
By adopting a functional sharing configuration in which the tertiary protector has a relatively small energy burden, and the secondary protector has an intermediate energy burden, it is possible to prevent a drop in the withstand voltage of the protected communication equipment. It is possible to obtain a communication protector that is compatible with the above, has few failures, and is highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional communication protector. 1...Primary protector, 11...Positive characteristic thermistor, 12...Grounding terminal, 13...
・Gas entry detonator, 14... Resistance element, 2...
... Secondary protector, 21 ... Ground terminal, 22.
... Metal oxide varistor, 3 ... Tertiary protector, 31 ... Resistance element, 32 ... Ground terminal, 33 ...... No. 1 diode, 34...
...Power supply terminal ('1n) s35...Second diode, A, C...External communication line side connection terminal, B, D...Protected communication Device side connection terminal, 4.
...Primary protector, 41...Ground terminal, 4
2...Gas inlet detonator, 43...Heat coil, 5...Secondary protector, 51...
Ground terminal, 52...Metal oxide varistor.

Claims (1)

[Claims] A positive temperature coefficient thermistor and a resistance element arranged in series on an internal communication line between an external communication line side connection terminal and a protected communication device side connection terminal, a connection point between the positive temperature coefficient thermistor and the resistance element, and a ground terminal. a first protector having a gas entry detonator inserted therebetween; and a second protector located after the first protector and having a non-linear resistance element between the internal communication line and the ground terminal. a resistive element located after the second protector and connected in series with the internal communication line, and a first diode whose anode is grounded and whose anode is connected to the internal communication line, and whose cathode is connected to a power supply terminal. and a third protector having a second diode connected to the internal communication line and having an anode connected to the internal communication line.