RU23718U1 - DEVICE FOR PROTECTING EQUIPMENT AGAINST VOLTAGE - Google Patents

Description

DEVICE FOR PROTECTING APPLIANCES AGAINST VOLTAGE

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

Known devices for protecting equipment from excess voltage 1, 2. To protect the equipment from high voltage currents, each such device contains a three-electrode gas-filled spark gap, two terminals of which are connected to the input terminals of the device for connection to the communication line, and the third terminal is connected to ground. The disadvantage is low speed and limited functionality, since they are intended only for two-wire lines. With short-term overvoltage pulses on the line, the electronic equipment may fail before the protection trips.

A device is also known for protecting communication equipment from excessive voltage 3. This device contains a spark gap and semiconductor devices - varistors, thermistors. Its disadvantage is limited functionality, as it is designed for two-wire lines only.

A device is also known for protection against lightning impulses of overvoltages of a two-wire communication line 4. This device contains a spark gap included in each of the wires, which is connected to each of the input terminals and the ground loop, electrical isolation resistors made in the form of reactors connected in series to each of the wires two-sided semiconductor limiters

IPC Н02Н 9/04

voltages connected between output terminals and ground

contour. Its disadvantage is also limited functional

possibilities, since it is intended only for two-wire communication lines.

A device is also known for protection against lightning surge surges

three-wire communication line 5.

It can be used for digital surge protection

telephone exchanges and subscriber equipment; contains thermistors,

varistors and arresters. The device is connected to a grounded wire and to

two other wires of a three-wire line.

However, it has limited functionality - not

Designed for four-wire communication lines.

Closest to the claimed invention is a device for surge protection according to US patent 6.

According to Patent 6, for protecting the system shown in FIG. 1, communication between objects 1, 2, 3 is made by means of four-wire lines. For communication between objects 1 and 2, two two-wire cables with wires 4, 5 and 6, 7 were used. For communication between objects 2 and 3, two two-wire cables with wires 8, 9 and 10, 11 were used. One of the two-wire cables is intended for transmission, and the second for admission. For each two-wire cable, a separate such protective device is used - 12, 13 and 14, 15, connected respectively to wires 4 - 7, 8 - 11.

Such a surge protection device according to US Pat. No. 6 is shown in the diagram (FIG. 2). It contains two input signal terminals 16, 17 for connecting to the wires of the communication line, two output signal terminals 18, 19 for connecting the protected equipment, terminal 20 for connecting the ground, the first stage of protection 21 on the gas-filled spark gap 22,

connected to the input signal terminals 16, 17 and the ground terminal 20, the second stage of protection 23 on the varistor 24, electrical isolation resistance 25, 26.

A disadvantage of such protection is that the protection devices of FIG. 2 have limited functionality, as they are intended for two-wire lines only, and a separate protection device is required for each pair of wires.

The problem, which is aimed by the claimed utility model, is to eliminate these shortcomings; in expanding the functionality to ensure the protection of equipment connected to a four-wire communication line, one protection device, instead of the traditionally used two well-known devices designed for two-wire lines.

The technical result achieved in this case is to increase the reliability of the protection device by reducing the number of connections of the protection devices with the protected equipment, as well as to reduce the structural complexity of the protection systems.

To achieve the specified technical result

a device for protecting equipment from overvoltage, containing one protection channel, which includes: two input terminals for connecting to a communication line; two output terminals for connecting protected equipment; grounding bus;

a three-electrode gas-filled spark gap, the two terminals of which are connected to the input terminals of the device, and the third terminal is connected to the ground bus; two dividing eletricheskie resistance.

each of which is connected with one output to one of the input terminals, and the second output is connected to the corresponding output terminal, semiconductor devices with the characteristics of symmetric diode thyristors, interconnected in the form of a three-beam star, two of which are connected to two output terminals of the device, and the third to the ground bus

made as follows, distinguishing it from the known.

Additionally introduced a second protection channel

with an electrical circuit identical to the circuit of the first channel mentioned above, and the grounding buses of both channels are combined and connected to a common ground connection for both channels.

In the particular case of execution, wire resistors from a wire with high electrical resistance placed on a heat-conducting base are installed as separation electrical resistances in both channels.

In the particular case of execution, elements with a positive temperature coefficient of resistance are installed as separation electrical resistances.

Signs that distinguish the proposed device from the known one are that the device is dual-channel with a single ground terminal common to both channels.

Such uniform execution of schemes of the first and second stages of protection simplifies their calculations and coordination of operating modes, simplifies maintenance and repair of the device. Using one pin to connect the ground instead of two leads reduces the transient resistance in the ground circuit.

The essence of the proposed utility model is illustrated by the following drawings.

In FIG. 1 shows a diagram similar to that described in patent 6 of a communication system with a four-wire communication line between objects, in which one protection device is used for each pair of wires.

In FIG. 2 is a diagram of a surge protection device described in Patent 6 and used in the system of FIG. 1.

In FIG. 3 shows the proposed circuit of an electrical device for protecting equipment connected to four wires of a communication line, through one common protection device for both channels.

In FIG. 4 shows a diagram of a communication system with a four-wire communication line between objects, similar in functionality to that shown in FIG. 1, but with the use of one proposed protection device for each four wires of each of the communication lines.

Depicted in FIG. 1 is described in patent 6. This known communication system with a four-wire communication line between objects 1, 2, 3, for each pair of wires 4, 5; b, 7; and 8, 9; 10.11 uses one protection device 12, 13; and 14, 15.

(In the communication line, one pair of wires can form one channel, for example, the transmitting one, and the second pair of wires can form the second channel, for example, the receiving one.)

A diagram of the known surge protection device used in the system of FIG. 1 described in Patent 6 is shown in FIG. 2.

The findings 16, 17, intended for connection to the communication line, are the input terminals of the protection device. Through them, useful signals and overvoltage lines appear. Output pins 18, 19 of the device

5 11v5 / 6

protections are designed to connect the input or output terminals of the protected equipment. Pin 20 is for grounding. The first stage of protection 21 contains a gas-filled spark gap 22, the second stage of protection 23 contains a varistor 24.

Between the first and second steps, separation electrical resistors 25, 26 are installed.

The proposed circuit of an electrical device for protecting equipment connected to four wires of a communication line through one common protection device for both channels is shown in FIG. 3. It contains the following elements.

The input terminals 27, 28 and the output terminals 29, 30 of the first channel of the device and the common ground terminal 31 for the first and second channels. The first stage of protection 32 on the gas-filled spark gap 33. The second stage of protection 34, with two-sided semiconductor voltage limiters on semiconductor devices 35, 36 , 37 with the characteristics of symmetric diode thyristors, which are interconnected in the form of a three-beam star; two beams of this star with semiconductor devices 36, 37 are connected to two output terminals of the device, and a third beam with a semiconductor device 35 is connected to the ground bus 31. Two isolation electrical resistances 38 and 39, with one terminal connected to the input terminals 27 and 28, respectively, and the second conclusions are connected to the corresponding output terminals 29 and 30.

Additionally introduced according to the utility model, the second protection channel has an electrical circuit identical to that of the first channel. The second channel contains the following elements. Input terminals 40, 41, output terminals 42, 43 and ground terminal 31, common

for both channels.

The first stage of protection 44 on a gas-filled spark gap 45. The second stage of protection 46 on semiconductor devices 47, 48, 49 with the characteristics of symmetric diode thyristors, which are interconnected in the form of a three-beam star; two beams of this star with semiconductor devices 48, 49 are connected to two output terminals of the device, and a third beam with semiconductor device 47 is connected to the ground bus 31, which, according to a utility model, is common for both channels. Two electrical isolation resistances 50 and 51, with one terminal connected to the input terminals 40 and 41, respectively, and the second terminal connected to the corresponding output terminals 42 and 43.

In the particular case of execution, it is provided that wire resistors from a wire with high electrical resistance placed on a heat-conducting base, which serves to remove heat from the resistor wire, are installed as separation electrical resistors 38, 39, 50, 51.

In another particular embodiment, it is provided that elements with a positive temperature coefficient of resistance are installed as separation electrical resistances 38, 39, 50, 51, an increase in the resistance of which, when they are self-heating from the overvoltage current, reduces the current through the elements of the second-stage circuit.

When using the proposed protection devices, instead of the four devices 12-15 shown in FIG. 1, two devices are sufficient, as shown in FIG. 4.

protection device 62, 63.

This communication system with a four-wire communication line between objects of FIG. 4, for a function similar to that shown in FIG. 1, but with the use of one proposed protection device for each four wires of each of the communication lines.

The device shown in FIG. 3 works as follows. Under normal operating conditions and there is no overvoltage at the inputs of the first protection channel 27, 28 connected to the communication line, the useful signal passes without significant attenuation through electrical resistances 23 - 39 to outputs 29, 30. Since the maximum voltage amplitude of the useful signal is insufficient for protection to operate , then neither symmetric diode thyristors 35 - 37, nor gas-filled spark gap 33 do not work.

When an increased voltage, the value of which exceeds the threshold voltage to turn on the protection, appears between the wires of the protection device connected to the terminals 27, 28, the corresponding symmetrical diode thyristors 36 - 37 having a short turn-on delay time are first turned on. Then the total voltage drop across the connected symmetric diode thyristors 36 , 37 and in series with them the separation resistances 38, 39 gradually exceeds the operating voltage of the connected arrester 33, and the discharge nick works. The response delay time of the arrester 33 is longer than that of the symmetric diode thyristors 35 - 37, therefore, protection on the symmetric diode thyristors always works first, and then on the arrester. Overvoltage pulses, as well as useful signals, do not pass to the output terminals 29, 30 of the device and the protected equipment. If the arrester 33 of the first stage of protection 32 were connected in parallel with a symmetrical diode

thyristors 36, 37 of the second stage directly, and not through dividing

resistance 38 and 39, then the gas-filled spark gap 33 could work

only after the burnout of at least one of its shunts

symmetric diode thyristors 36 and 37.

The permissible current through the arrester 33 significantly exceeds the permissible current

through symmetric diode thyristors 35 - 37, and the operation of the arrester

protects these symmetrical diode thyristors from potential long-term

over current.

After the termination of the overvoltage, the current through the resistance 38, 39

decreases, the symmetric diode thyristors 36, 37 are locked.

The voltage at the corresponding output of the device during its operation 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 turn-on of the symmetric diode thyristor and the turn-on delay time of the symmetric diode thyristor; the pulse amplitude is equal to the dynamic threshold voltage of the inclusion of a symmetric diode thyristor. After turning on the symmetric diode thyristor, the output voltage drops to the voltage drop across this symmetric diode thyristor. Thus, the input voltage is limited to the level of voltage drop on two series-connected symmetric diode thyristors 36, 37. After a period of time equal to the sum of the rise time of the input voltage to the threshold voltage of the spark gap and the delay time of its operation, the spark gap goes into a conducting state. In the conductive state, the voltage drop across the arrester is small; the current of the overvoltage pulse flows through two parallel circuits through the arrester 33 and also through the symmetric diode thyristors Zb, 37 and resistance 8.39, and the voltage at the output terminals is determined by the voltage drop across the symmetrical diode thyristors 36, 37. When the input voltage decreases, the current through arrester and symmetric diode thyristors. Further, the current decreases to a level at which the spark gap is turned off, and the current continues to flow for some time through the resistance 38, 39 and through the symmetric diode thyristors. A further decrease in current through symmetrical diode thyristors leads to their shutdown.

When an overvoltage occurs between the ground and terminal 27, the protection on the symmetric diode thyristors 35, 36 is first triggered, and then on the spark gap 33 with a ground discharge through the grounded terminal 31. The processes are similar to those described above.

When an overvoltage appears between the ground and terminal 28 or between the ground and terminals 27, 28, the device operates similarly to that described for the case of a signal to terminal 27. A symmetric diode thyristor 35 and 37, or 35 and 36, 37, and then a spark gap 33 are triggered.

The operation of the second channel with the conclusions 40, 41 and 42, 43 is similar to that described for the first channel.

The use of a single device for surge protection on a communication line according to this PM allows you to replace several known devices designed to protect only two-wire communication lines, which simplifies the protection system.

Instead of a single symmetrical diode thyristor, several series-connected symmetric diode thyristors can be used. Instead of one or more symmetrical diode thyristors, there may be

equivalent modules or microcircuits with similar characteristics and complex electrical circuits are also used, for example, on thyristors with control circuits for their operation.

As a separation of electrical resistance can be used posistors - resistors made of ceramic semiconductor materials; positive temperature coefficient resistors made of special polymer materials; other elements with similar reversible characteristics or elements with switched circuits. As separation electrical resistances, circuit elements containing active and reactive resistances, and other nonlinear devices can also be used.

The arresters of the first stage of protection can be multi-electrode, with thermal protection, with switched circuits, and others, and in particular cases can be connected to the input and ground terminals in other ways.

The device increases the reliability of surge protection and can be used for lightning protection and other surge voltages on the communication line, including maintenance-free regenerative points. The device allows protection of equipment against overvoltages without false positives in cases where there is no overvoltage hazardous to the equipment on the communication line, with optimal protection thresholds and with fewer protection devices in communication systems than when using other known devices.

Sources of information

1. Yu. N. Kornyshev, A. Ya. Markovich, M.N. Pisker, V.M. Romantsov. Fixed equipment of rural telephony. - M .: “Radio and communications. - 1990. - S. 280, Fig. 15.1 c).

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2. GOST 5238-81 Protection schemes against hazardous voltages and currents arising on the lines. Technical requirements. - M .: “IPK Publishing House of Standards. 1998.

3. RF Application No. 94000893 - Device for protecting two-wire lines against overvoltage, MPK® Н02Н 9/04, publ. 1995.

4. RF patent No. 2050663 - Device for protection against lightning impulses of overvoltage of a two-wire communication line, IPC Н02Н 9/04, publ. 1995.

5. RF Application No. 94000895, IPC Н02Н 9/04, Device for protecting three-wire lines against overvoltage, publ. 1995.

6. US Patent No. 52722588 - Surge protector, U.S. Class 361/119, IPC H02H 9/04, publ. 1990. The author of the utility model: E. A. Ivanov

Claims (3)

1. Device for protecting equipment from overvoltage, containing one protection channel, which includes two input terminals for connecting to a communication line, two output terminals for connecting protected equipment, a grounding bus, a three-electrode gas-filled spark gap, two terminals of which are connected to the input terminals of the device and the third terminal is connected to the ground bus, two dividing electrical resistances, each of which is connected with one terminal to one of the input terminals, and the second terminal is connected with the corresponding output terminal, semiconductor devices with the characteristics of symmetric diode thyristors, interconnected in the form of a three-beam star, two beams of which are connected to two output terminals of the device, and the third to the ground bus, characterized in that a second protection channel with an electrical circuit is additionally introduced, identical to the circuit of the first channel mentioned above, and the grounding buses of both channels are combined and connected to a common ground for both channels.  2. The device according to claim 1, characterized in that the wire resistors of a wire with high electrical resistance, located on a heat-conducting base, are installed as separation electrical resistors. 3. The device according to claim 1, characterized in that elements with a positive temperature coefficient of resistance are installed as dividing electrical resistances.