SU1367092A1 - Device for protecting communication line equipment against overvoltages - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to increase the reliability of protection by reducing the voltage on the protected equipment by eliminating the influence of the working signal. An overvoltage impulse in the form of a longitudinal voltage is supplied to the transverse component extraction unit 6, which occurs due to the difference of the longitudinal stresses induced on both wires of the line 7, as well as due to the asymmetry of the input circuits of the protected equipment. When the polarity of the overvoltage pulse is negative, transistor 1 operates and shunts the input of the equipment to be protected. When the polarity of the overvoltage pulse is positive, transistor 2 operates. Reliability increases due to the fact that the operating signal is a transverse signal and is absent at the outputs of block 6. 2 h. P. f-ly, 3 ill. with o (L

Description

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The invention relates to electrical engineering and can be used for protection against impulse overvoltages of equipment of transmission systems installed on unattended and serviced amplification points of cable communication lines.

The purpose of the invention is to increase reliability by reducing the voltage on the protected equipment by eliminating the influence of the working signal.

Fig, 1 shows a block diagram of the proposed device, on

Figs. 2 and 3 show examples of implementation of a block 15 which are led to both wires of a line 7 for separating a longitudinal component. field voltages as well as

The device contains the first 1 and second 2 transistors, the first 3 and the second 4 diodes,

A diode bridge circuit 5 and a block 6 for extracting the longitudinal component of an overvoltage pulse, the inputs of which are connected to the communication line 7, the first and second protective outputs to the inputs of the hard-core apparatus 8, the third protective output to the ground, and the first and second control outputs to the inputs of the introduced bridge circuit 5, anodic and cathodic

the outputs of which are connected to bases; soo signals are fed to the inputs of the pavement

responsibly transistors 1 and 2, the collectors of transistors 1 and 2 are connected respectively to the anode and cathode of diodes 3 and 4, the second terminals of which are interconnected and connected to the first protective output of the allocation unit 6, and the emitters of the transistors to the second protective output of block 6, and the transistor 1 has a pp, - and the transistor 2 pp - conductivity.

The unit 6 for allocating the longitudinal component of the overvoltage pulse (FIG. 2) contains the first 9 and second 10 differential transformers, a resistor 11 and a pair of counter-enabled Zener diodes 12,

In the particular case, if the protected equipment has a balanced input, the output unit 6 (FIG. 3) can be implemented as a differential transformer 13, a resistor 14 and two pairs of counter-connected Zener diodes 15 and 16 connected in series. When using block 6 in the communication lines with remote power supply, between the midpoint of the differential transformer 9 and the resistor 11 must turn on the capacitor

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circuits 5, through which the shunt transistors 1 and 2 arrive

At each of the control outputs of block 6, a positive or negative polarity signal may appear relative to the emitters of the transistors 1 and 2, depending on the polarity of the voltage induced on the wiring line 7, thanks to connecting 40 bridge circuit 5 to the base Transistor 1, which has pnp conductivity, always receives a negative control relative to the emitter, and control transistor 2, which has pnp conductivity, is positive relative to the emitter control potential.

With negative polarity, the induced voltage at the output of block 6 relative to the emitters of transistors 1 and 2 triggers a circuit of successively connected transistors

1 and diode 3 and shunts the input of the protected equipment 8, and with a positive polarity - a circuit of the transistor

2 and diode 4, diodes 3 and 4 protect transistors from reverse polarity voltages. The magnitude of the induced voltage arriving at the device input

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The device works as follows.

An overvoltage impulse is induced on one or both of the wires of line 7 in the form of a longitudinal voltage (which is the positive or negative potential between the wire and ground. The longitudinal voltage is applied to the block 6 (Fig. 1)). 6, the transverse component of the overvoltage pulse U, which arises due to the difference in the asymmetry of the input circuits of the protected equipment 8, appears. The transverse component of the overvoltage pulse arrives

20 to the input of the protected equipment, in parallel with which an electronic key circuit is included, containing shunt transistors 1 and 2, protective diodes 3 and 4, and a diode bridge circuit

25, circuit 5; The signals from the longitudinal component of the overvoltage pulse appear on the first and second control outputs of the extraction unit 6. Managers

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circuits 5, through which the shunt transistors 1 and 2 arrive.

At each of the control outputs of block 6, a signal of positive or negative polarity may appear relative to the emitters of transistors 1 and 2, depending on the polarity of the voltage induced on the wires of line 7, thanks to the bridge circuit 5, 0, which has pp-conductivity, the control potential is always negative with respect to the emitter, and the base of transistor 2, which has pp-conductivity, is positive with respect to the emitter control potential.

With negative polarity, the voltage applied at the output of block 6 relative to the emitters of transistors 1 and 2 triggers a circuit of series-connected transistors

1 and diode 3 and shunts the input of the protected equipment 8, and with a positive polarity - a circuit from the transistor

2 and diode 4, diodes 3 and 4 protect transistors from reverse polarity voltages. The magnitude of the induced voltage applied to the input of the device5

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Consequently, the transistor and the diode are open and do not exceed 3-5 V.

The working signal, coming through line 7 to the input of block 6, is a transverse signal and is completely absent at the control outputs of block 6. Thus, the electronic key circuit does not react at all to the voltage of the working signal, regardless of its value,

The longitudinal component extraction unit 6 operates as follows (Fig. 2).

The longitudinal voltage through the midpoint of the first differential transformer 9 is fed to a series circuit of a resistor 11 and a pair of 12 zener diodes connected in opposite direction, which is connected to ground with the other end. Resistor 11 serves to limit the current in the midpoint-to-ground circuit; in a pair of zener diodes it ensures a voltage drop across it equal to the stabilization voltage of the zener diodes. Each zener diode of pair 12 provides a voltage drop of respectively positive or negative polarity depending on the polarity of the induced voltage. The operating signal coming from line 7 to the primary winding of the transformer 9 is in its structure a transverse signal and there is no midpoint-ground circuit. Thus, the voltage drop across a pair of 12 zener diodes occurs only in the case of induced voltages - Q to exclude the influence of the operating signal having a longitudinal character. on setting the pickup threshold of the device, the voltage stabilizing the zener diodes occurs only in the case of induced voltages of a longitudinal nature.

The stabilization voltage of the zener diodes can be chosen by anyone regardless of the magnitude of the working signal, in particular, much less than it, which is impossible in the prototype and other analogues. Parallel to the pair of 12 zener diodes, a second differential transformer 10 is connected, through which control signals are generated to act on transistors 1 and 2. The middle point of the differential transformer 10 is connected to one of the wires of the secondary winding of the differential transistor.

Connected to the emitters of transistors 1 and 2 ". At each of the outputs of the secondary winding of the differential transformer 9, which are the control outputs of the allocation unit 6, a signal of both positive and negative polarity with respect to the polarity may occur on a pair of 12 zener diodes. Thus, with a negative polarity of the voltage on the Zener diodes, the output I of the differential transformer 10 has a control signal of negative polarity relative to the midpoint, and the output 2 has a positive polarity. With a positive polarity, the voltage at the zener diode at the output of I is positive, the voltage of the positive polarity at the output of II is negative.

In the particular case5 when the input of the protected equipment 8 is balanced (absent), the execution of the allocation unit 6 can be simplified (Fig. 3). In this case, the control signals of the required field pliocTH can be formed using

two pairs 15 and 16 series-connected zener diodes 5, the connection point of which is connected to one of the wires of the secondary winding of the differential transformer 13.

The feasibility of using the proposed device is as follows. The introduction of new blocks with their connections allows

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Protection systems and, accordingly, reduce the induced voltage at the input of the protected equipment, which ultimately leads to an increase in the reliability of protection using the proposed device. The increase in the reliability of protection is also manifested in the fact that the proposed device works only on induced voltages and does not respond to the working signal at all, regardless of its size, which prevents possible spurious triggers during jumps in the level of the working signal and, accordingly, short interruptions .

Claims (3)

Claim 1 Invention device for protection against overvoltages of equipment of communication lines. comprising two transistors and two diodes, characterized in that, in order to increase the reliability of the protection by reducing the voltage on the protected equipment by eliminating the influence of the operating signal, the bridge diode and the block for the longitudinal component of the overvoltage pulse are introduced into it, the Q inputs which are connected to the terminals for connection to the communication line, the first and second protective outputs are connected to the terminals for connection to the inputs of the equipment to be protected, the third protective output is 15 to ground, and the first and second control signals are to the inputs bridge circuit, the anodic and cathodic outputs of which are connected to the bases of the first and second transistors, respectively, the collectors of the transistors are connected respectively to the anode and cathode of the diodes, the second outputs of which are interconnected and connected to the first protective output of the longitudinal selection unit 25 the overvoltage pulse, and the emitters of the transistors - to the second protective output, the first and second transistors having, respectively, pnp and pnn conductors, and a block in the longitudinal component containing t differential transformer and generator of various control signals, connected through a resistor between the average about 5 13670926 the point of the primary winding of the differential transformer and the ground, the first and second outputs of the control signal generator are the control outputs of the longitudinal component, and the third output, in relation to which different polarity control signals are formed, is connected to the emitters of transistors, 2. The device according to claim 1, characterized in that the driver of the multi-polar control signals contains a differential transformer, in the primary winding of which a pair of opposite-connected zener diodes is included, and its secondary winding is made with a midpoint, and the secondary windings are control outputs control driver, and the middle point output is its third output. 3. The device according to claim 1, characterized in that the driver of opposite polarity control signals contains two pairs of oppositely connected Zener diodes connected in series, the terminals of the chain of Zener diodes being the control outputs of the signal conditioner and the common point of the pairs of oppositely connected Zener diodes - its third output. K 5 transformer and ground, the first and second outputs of the driver control signals are the control outputs of the block of the longitudinal component, and the third output, in relation to which different control signals are formed, is connected to the emitters of transistors, 2. The device according to claim 1, characterized in that the driver of the multi-polar control signals contains a differential transformer, in the primary winding of which a pair of opposite-connected Zener diodes is connected, and its secondary winding is made with a midpoint, and the secondary windings are control outputs of the driver control signals, and the midpoint output is its third output. 3. The device according to claim 1, characterized in that the driver of the multi-polar control signals contains two pairs of oppositely connected Zener diodes connected in series, the terminals of the chain of Zener diodes being the control outputs of the signal conditioner, and the common point of the pairs of oppositely connected Zener diodes is its third output . h / 15 I To scheme S Fig.Z W L M