SU754563A1 - Device for protecting communication line from overvoltage - Google Patents

Description

The invention relates to an automatic telephone and telegraph switching, advantageously to devices for protection, devices connected to the electric lines for electronic and quasi telephone station from ⁵ GOVERNMENTAL dangerous electrical influences, and can be used as a self-protection stage, or second stage after dischargers and decoupling chokes.

A device for protecting electrical lines and electronic equipment from overvoltage, containing ₅ zener diodes m.

A disadvantage of the known device is a small permissible power dissipation at the Zener diode, _Μ

as a result, zener diodes are of limited use, mainly in circuits with a low level of working voltage, (sealing equipment).

REINFORCEMENT

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It is also known a device containing security elements connected between the path wires, for example, dynistors] _2]

A disadvantage of the known device is the uncertainty of the threshold of the device, which leads to a decrease in the effectiveness of protection.

The closest technical solution to the proposed is a circuit for protecting communication devices from atmospheric noise, which contains protection elements on the thyristors connected between the path wires and the ground, and resistors included in the control circuit of each thyristor. This protection scheme is designed to protect communication devices against potential difference arising between the ground and the air line, communication line or cable And ·.

The disadvantages of the known devices are not sufficiently clear threshold response characteristics of the circuit, due to the presence of resistors and

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capacitors for control purposes; insufficient performance of the circuit due to the inertia of the operation of the tigristors. This leads to the transmission of a pulse and an overvoltage to the protected equipment, with a duration equal to the response time of the thyristor,

The circuit provides for two thyristors of unilateral conductivity for each wire or one symmetrical thyristor, which leads to a complication of the circuit.

The aim of the invention is to improve the performance and improve the threshold characteristics of the device.

This goal is achieved by the fact that semiconductor diodes and zener diodes are introduced into the device to protect the communication line against overvoltage, which contains thyristors connected between the path wires and ground, and resistors included in the control circuit of each thyristor. Thyristors are connected in series with each other in one direction and a common point is connected 25 to the ground, the anode of one semiconductor diode is connected to the path wire to which the cathode of one of the thyristors is connected, the cathode to another wire of the path connected to the anode of another thyristor. In the control circuit of each thyristor between the control electrode and the anode, a series-connected semiconductor diode and a zener diode are counter-connected. 35

The drawing shows a schematic diagram of a device for protection.

The device contains a semiconductor diode 1, thyristors 2, zener diodes 3 and diodes 4. _4θ

The anode of the semiconductor diode '1 is connected to the wire of the path to which the thyristor cathode is connected, the cathode to the other wire of the path to which the anode of the other thyristor is connected. However five- ₄₅ Ristori semiconductor diode 2 and 1 are used to protect equipment depending on the polarity of the voltage affecting, i.e. either one thyristor 2 or semiconductor diode 1 ₅₀ and another thyristor are opened, while the thyristors 2 are connected in series with each other in one direction and are connected to ground with a common point.

In the control circuit of each thyristor ₅₅ between the control electrode and the anode, a series-connected semi-arched diode% and a zener diode 3 are counter-connected. wire path. The zener diodes 3 in the control circuit of each thyristor are designed to turn on the corresponding thyristor at a voltage above the threshold response of the zener diode 3.

The device provides protection from overvoltage, from atmospheric influences, from electromagnetic impulses of a high-frequency electromagnetic field, from high-voltage transmission lines, etc.

The device works as follows (the application of voltage to the upper wire is considered).

When the voltage is above the threshold of the Zener diode 3, the latter opens and through the control switch? the stroke of the corresponding thyristor 2 begins to flow control current, as a result of which the thyristor 2 opens. If the polarity of the affecting voltage is positive., The semiconductor diode 1 and the lower thyristor 2 open. If the polarity of the influencing voltage is negative, the upper thyristor 2 is triggered. Similarly, the device operates relative to the lower wire when the external voltage polarity changes.

Compared with the known, the proposed protection device provides improved performance by using the inertia-free control circuits of the thyristors as a protection step, improves the threshold characteristics of the device due to the use of control circuits of thyristors with small rasbrosov electrical parameters, such as stabilization voltage, except that the control circuit of each thyristor diode, directed in opposite direction with respect to the zener diode, reduces the requirements for thyri torus on the reverse allowable voltage "control electrode - the cathode."

Claims (1)

Claim A device to protect the communication line from overvoltage, containing thyristors connected between the path wires and ground, and resistors included in the control circuit of each thyristor, 5 754563 | characterized in that, with the purpose of improving performance and improving the threshold characteristic, semiconductor diodes and zener diodes are introduced, while the thyristors are connected in series with each other in one direction and the common point is connected to earth, the anode of one semiconductor diode is connected to the path wire, the cathode of one of the thyristors is connected, the cathode is connected to the other wire of the path to which the anode of the other thyristor is connected, with the control circuit of each thyristor between control electrode and anode counter-connected in series semiconductor diode and zener diode.