RU21316U1 - VOLTAGE PROTECTION DEVICE FOR TELECOMMUNICATION EQUIPMENT - Google Patents

Description

TELECOMMUNICATION VOLTAGE PROTECTION DEVICE

EQUIPMENT

The utility model relates to the field of electrical engineering, namely, to schemes for protecting telecommunication equipment against excessive voltage, which respond to voltage above normal, without disconnecting the protected equipment from communication lines.

Known devices for protecting communication equipment from excessive voltage, described in the book: Yu. I. Kornyshev, A. Ya. Markovich, M. I. Pisker, V. M. Romantsov Stationary equipment for rural telephone communications, Moscow, Radio and communications, 1990 ., p. 280, fig. 15.1 c) - protection scheme for connecting cable lines. To protect the equipment from high voltage currents, the device contains a three-electrode gas-filled spark gap, two terminals of which are connected to the input terminals of the device intended for connection to the communication line, and the third terminal is connected to ground. Its disadvantage is not high enough speed.

It is also known a device for protecting communication equipment from excessive voltage, application No. 94000893 - Device for protecting two-wire lines from overvoltages. This device contains a spark gap and semiconductor devices varistors, thermistors. Its disadvantage is not high enough speed.

A device for surge protection is also known - the invention according to the patent of the Russian Federation No. 2050663 - Device for protection against lightning impulses of overvoltages of a two-wire communication line. This device contains an arrester included in each of the wires, which is connected to each of the input terminals and the ground loop, electrical resistances made in the form of chokes included

sequentially in each of the wires, bilateral semiconductor voltage limiters connected between the output terminals and the ground loop.

This surge protection device is the closest to the claimed utility model in its essence and technical result.

However, such a technical solution has the following disadvantages.

With this technical solution, the threshold voltage of protection of the equipment from pulse differential overvoltages, i.e. from overvoltages, directly between two wires of the communication line, at which two series-connected voltage limiters are triggered, is greater than the threshold voltage at which the protection against common-mode overvoltages is activated, i.e., overvoltages between ground and one or both wires of the communication line, at which one of the limiters can be triggered or both. This is due to the use of the same two limiters to provide protection against both differential and common-mode overvoltages, although the threshold voltages for these overvoltages can generally be independent and can vary significantly in magnitude.

In many cases, the value of common-mode voltages acceptable for equipment is greater than for differential ones. However, in this technical solution, at the selected optimal threshold of protection against differential overvoltage determined by the parameters of two series-connected voltage limiters, the threshold for common-mode overvoltage is automatically lower than from differential, since in the latter case, not two series-connected limiters are switched on during overvoltages, but only one of them, and the threshold of the device is determined by the parameters of only one of the limiter nd, not two. This leads to a deterioration in the quality of communication due to additional interference introduced by the device during false positives, when this protection might not turn on without danger to the equipment, and, in addition, leads to overheating of the elements of the device.

Therefore, at a given optimal threshold voltage for tripping the protection against differential overvoltages, the threshold voltage for tripping the equipment against surge common-mode surges is not optimal for such a circuit. Protection can operate at common-mode voltages, the amplitude of which is acceptable and safe for equipment, i.e., in fact, such voltages are not overvoltages, which increases the total time of current flow through the limiters and their heating, and creates additional communication interference. If the permissible common-mode voltage amplitude for equipment is higher than differential, then this solution does not allow to implement a device with appropriate protection thresholds that could satisfy such requirements. With such a scheme, it is impossible to set the optimal threshold protection voltage.

As voltage limiters in such devices, zener diodes are predominantly used, which have a significant parasitic capacitance, which increases the attenuation of the useful signal on the communication line; this is also a disadvantage. In addition, during prolonged exposure to overvoltages, for example, during a series of pulses of long duration and large overvoltages, for example, due to the effects of lightning overvoltage impulses, voltage limiters due to their high stabilization voltage can fail due to overheating.

The problem to which the claimed utility model is directed is to eliminate these drawbacks, to improve communication quality by eliminating false alarms of protection and to reduce additional noise introduced by the device, to increase the reliability of the protection device by reducing the overheating of device parts by current flowing during overvoltage.

The technical result achieved in this case is as follows: to increase the reliability of the protection device by optimizing its threshold voltage of the overvoltage protection on the communication line, depending on the allowable values of common-mode and differential voltages connected to

communication lines of equipment outputs, due to this false alarms are eliminated

protection;

to increase the reliability of the protection device by reducing the likelihood of overheating

and failure of semiconductor voltage limiters with pulse

overloads;

and, in addition, in reducing the signal attenuation introduced by the device in the communication line beyond

by reducing the parasitic capacitance of the device parts.

To achieve the specified technical result with this task, a device for surge protection of telecommunication equipment, containing:

a three-electrode gas-filled spark gap, the two terminals of which are connected to the input terminals of the device for connecting to the communication line, and the third terminal is connected to the ground terminal;

two-sided semiconductor voltage limiters connected to the output terminals of the device designed to connect protected equipment; two electrical resistances, in each of which one terminal is connected to the input terminal, and the second terminal is connected to the corresponding output terminal of the device; performed as follows:

the number of said two-way semiconductor voltage limiters is at least three, they are interconnected in the form of a triangle, two vertices of which are connected to two output terminals of the device, and the third to the ground terminal;

voltage limiters are made on semiconductor devices with the characteristics of symmetrical dynistors, and with a delay time of their inclusion less than the delay time of operation of the aforementioned three-electrode gas-filled spark gap;

have the same parameters;

and each of the two electrical resistances is made in the form of a wire resistor from a wire with high electrical resistance, placed on a heat-conducting base.

The drawing shows a diagram of an electrical device, where are indicated: 1,2- input pins intended for connection to a communication line;

3- three-electrode gas-filled spark gap;

4- grounding terminal;

5, 6 - wire resistors;

7.8 - output terminals of the device designed to connect protected

equipment;

9, 10, 11 - symmetric dinistors or similar semiconductor devices with

characteristics of symmetrical dinistors.

Conclusions 1, 2, intended for connection to the communication line, are input for overvoltage coming from the communication line to the protection device. Conclusions 7.8 - output conclusions of the protection device, however, they can be connected to both the input of the protected equipment and its output.

Input terminals 1, 2 of the protection device are connected to two terminals of a three-electrode gas-filled spark gap 3, the third terminal of which is connected to the ground terminal 4. Terminals 1, 2 are also connected to the first terminals of two electrical resistances 5, 6, the second terminals of which are connected to the corresponding output terminals 7 , 8 devices designed to connect protected equipment. Each of the two electrical resistances 5, 6 is made in the form of a wire resistor made of a wire with high electrical resistance, placed on a heat-conducting base in order to increase the overload capacity in case of pulse overloads with overvoltage currents.

Symmetric dinistors 9, 10, 11 or similar semiconductor devices with the characteristics of symmetrical dinistors are interconnected in the form of a triangle, two vertices of which are connected to two output terminals 7, 8 of the device, and the third to ground terminal 4.

The switching voltage of the dinistor 9 is selected taking into account the differential voltages acceptable for the equipment, and the dinistors 10, 11 - taking into account the common-mode voltages acceptable for the equipment.

Symmetric dinistors 10 and 11 have the same parameters, as a result of which equal protection conditions are provided for overvoltages arising either between terminals 1 and 4, or between terminals 2 and 4, or simultaneously between terminal 4 and terminals 1, 2.

The wire resistors 5, 6 are made with low thermal resistance between the wire from which they are made and the heat-conducting base on which this wire is located or wound, as a result of which they are more resistant to short-term power overloads, since the heat from the wire is transferred to the heat-conducting base protecting the wire from burnout.

The voltage drop on the symmetric dynistors 9, 10, 11 in the on state is much less than that of zener diodes, usually used as voltage limiters; accordingly, less heating of the dinistors by the flowing current.

In addition, the electrical capacitance of the symmetric dinistors 9, 10, 11 is significantly lower than the capacitance of conventional two-sided semiconductor limiters made on zener diodes. Therefore, the attenuation introduced by them at the higher frequencies of the useful signal is less.

The device operates as follows.

6 to the output 7, 8. The gas-filled spark gap 3 and the symmetrical dinistors 9, 10, 11 do not work, since the voltage amplitude of the useful signal is insufficient to trigger them.

When a differential overvoltage pulse appears at the input 1, 2 connected to the communication line, the value of which exceeds the threshold voltage for switching on the symmetric dinistor 9 and the spark gap 3, first the transistor 9 having a short turn-on delay time is turned on. Then, the total voltage drop across the resistors 5, 6 and on the dinistor 9 gradually exceeds the operating voltage of the arrester 3, and the arrester is triggered. The delay time of the arrester 3 is longer than that of the symmetric dinistor 9. During this period, before the arrester 3 is triggered, the overvoltage pulse current flows through resistors 5, 6 and dinistor 9. Due to the heat removal from the wire from which the resistors 5, 6 are made, on the heat-conducting base on which this wire is located, there is no significant heating of the resistors 5, 6, which protects them from failure. Overvoltage pulses do not pass to the output terminals 7, 8 of the device and the protected equipment. If resistors 5, 6 were absent, the arrester 3 could work only after the combustion of the shunting dinistors. The permissible current through the arrester 3 significantly exceeds the permissible current through the dynistors, and the operation of the arrester protects the dynistors from current overloads.

The voltage at the output of the device in this case has the following form. First, a short-term pulse appears, the duration of which is determined by the sum of the rise time of the input voltage to the threshold voltage of the dynistor and the turn-on delay time of the symmetric dynistor 9; the pulse amplitude is equal to the dynamic threshold voltage of the inclusion of the dynistor. After turning on the dinistor 9, the output voltage drops to the value of the voltage drop across this dinistor.

Arrester 3 goes into a conducting state in which the voltage drop across it is small; the current of the overvoltage pulse flows through two parallel circuits - through the arrester 3 and through the dinistor 9 with wire resistors 5, 6, and the voltage at the terminals 7, 8 is determined by the voltage drop across the dinistor 9.

When the input voltage decreases, the current through the arrester 3 and the dinistors 9 decreases. Then the current decreases to the level at which the arrester is turned off and the current continues to flow through the dynistor 9. A further decrease in the current through the dynistor 9 leads to its shutdown.

When an overvoltage pulse appears at the input between terminal 1 connected to the communication line and ground terminal 4, the amplitude of which exceeds the threshold voltage for switching on the dynistor 10 and the arrester 3, the dynistor 10 is first turned on, then the arrester 3 is activated, protecting the section of the electric circuit between pin 4 and output pin 7 of the device, and protected equipment connected to the device. Otherwise, the operation of the device is similar to the operation described above with differential overvoltages.

When an overvoltage pulse appears at the input between terminal 2 connected to the communication line and ground terminal 4, the dynistor 11 having a view of the camera’s action is first turned on, and then, due to a voltage drop on the wire resistor 6 and on the dynistor 11, the arrester 3 is activated, protecting against overvoltage a section of the electrical circuit between terminal 4 and output terminal 8 of the device, and protected equipment connected to the device. Otherwise, the operation of the device is similar to the operation described above with differential overvoltages.

When a common-mode overvoltage pulse appears between terminal 2 connected to the communication line and ground terminal 4, and simultaneously between terminal 1 connected to the communication line and ground terminal 4, first, due to the variation in the parameters of the dynistors 10, 11, a more high speed dinistorYu or 11, and then the second dinistor and both dinistors 10 and 11 turn on

turn on. Due to the voltage drop across the resistors 5, 6 and on the dynistors 10, 11, a spark gap 3 is triggered, protecting a section of the electrical circuit between terminal 4 and the output terminals 7, 8 of the device from overvoltage, and the protected equipment connected to the device. Otherwise, the operation of the device is similar to the operation described above with differential overvoltages.

A close to optimal ratio between the protection thresholds for various common-mode and differential overvoltages is set by the appropriate choice of the operating voltage of the symmetrical dinistor 9 for differential voltages, and 10 and 11 for common-mode ones.

Instead of a single symmetrical dinistor 9, as well as instead of 10, 11, several dinistors connected in series can be used.

Instead of symmetrical dinistors, modules or microcircuits with the same characteristics and complex electrical circuits can be used, for example, on thyristors with control circuits for their operation.

Instead of all or part of the triangle-connected semiconductor devices, modules or microcircuits containing them may be used, including those in which the corresponding connections of these semiconductor devices are made.

Instead of two separate wire resistors 5, 6, a module containing these resistors can be used.

The device increases the reliability of surge protection and can be used for lightning protection and other overvoltages on the communication line, including maintenance-free regenerative points powered by phantom circuits. The device allows protection of equipment against overvoltages without false positives if there are no overvoltages hazardous to equipment on the communication line, with optimal protection thresholds for both common mode and differential overvoltages on the communication line.

Sources of information

1.Yu. N. Kornyshev, A. Ya. Markovich, M.N. Pisker, V.M. Romantsov Stationary equipment for rural telephone communications, Moscow, Radio and communications, 1990, p. 280, fig. 15.1 Q).

2. RF Application No. 94000893 - Device for protecting two-wire lines from overvoltage.

3. RF patent No. 2050663 - Device for protection against lightning impulses of overvoltage of a two-wire communication line. Author of utility model // / 7- - Ivanov

Claims (1)

A surge protection device for telecommunication equipment containing a three-electrode gas-filled spark gap, two terminals of which are connected to the input terminals of the device intended for connection to the communication line, and a third terminal is connected to the ground terminal, two-sided semiconductor voltage limiters connected to the output terminals of the device intended for connection protected equipment, two electrical resistances, each of which has one output connected to the input output and the second terminal is connected to the corresponding output terminal of the device, characterized in that the number of said two-way semiconductor voltage limiters is at least three, they are interconnected in the form of a triangle, two vertices of which are connected to two output terminals of the device, and the third to the terminal grounding; voltage limiters are made on semiconductor devices with the characteristics of symmetric dynistors, and with a delay time of their inclusion less than the delay time of the aforementioned three-electrode gas-filled spark gap, and semiconductor devices belonging to those two sides of the triangle, which are connected to the ground terminal and two output terminals of the device, have the same parameters, and each of the two electrical resistances is made in the form of a wire resistor from a wire with high m electrical resistance, placed on a heat-conducting base.