SU881931A2 - Device for overvoltage protection of communication line - Google Patents

Description

(54) DEVICE FOR PROTECTION OF COMMUNICATION LINE FROM OVERVOLTAGE

I

The invention of fire-switching to automatic telephone and telegraph switching, mainly to devices for building smartphones, connected with electric lines on electronic and quasielectrical PBX from hazardous electrical effects, and can be used as a stand-alone step or sewn into a second step after discharge dnik and developing schyussepy.

According to the main author. St. No. 754563 discloses a device comprising thyristors connected between the path wires and the ground, and resistors included in the latching circuit of each thyristor, as well as semiconductor diode diodes, while the thyristors are connected in series with each other in the same direction and connected to ground with a common point. The anode of a semiconductor diode, connected between the conductor path, is connected to the cathode of one of the thyristors, the cathode of this diode is connected to the anode of the other thyristor, and in the control circuit

Each thyristor between the control electrode and the anode is counter-switched on / series-connected semi-vanadiode diode and zener diode. The speed of operation, a clear threshold response characteristic, simplicity of the circuit design are characteristic for the ycTpoJ. This device provides protection from overvoltages, from weathering, from high-frequency electro-10 impulses to a fertile field, from high-voltage power lines, etc. Cll.

However, this device is not provided to protect line equipment from dangerous currents.

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Claims (3)

The most common way to protect the device on semiconductor devices from over-current is to use fuses. Fuse protection is possible if up to 20 the empty current of the device and the time of permissible current overload are longer than the time of the fuse-link rupture. In case of non-observance of this condition, the device goes out of order 36 and the fuse protection is impossible. In practice, it is also important that the protection circuit has multiple operations and an acceptable response time. Fuses and other known current protection devices are slow-acting devices and in most cases do not protect electronic equipment. The purpose of the invention is to expand the functionality of the device by providing protection not only against dangerous voltages, but also against dangerous currents. This goal is achieved by the fact that in the overvoltage line protection device, an input circuit of the thyristor optocoupler, shunted by a resistor, is sequentially connected to each conductor of the path, and the output circuits of the thyristor optocouplers are connected in parallel to the zener diodes of the thyristor control circuits. The drawing shows a schematic diagram of the proposed device sewn. The input circuits of the thyristor optocouplers 1 are included in the path wires from the PBX, and the output circuits are parallel to the zener diodes 2. Thyristor optocouplers 1 are used to turn on the corresponding thyristors 3 with an increase in the current in the line above the permissible value. Resistors 4, shunting the input circuit of the thyristor optocouplers 1, set the allowable amount of current in the line. Diodes 5 in the control circuits of each thyristor are designed to protect a control transition — a cathode transition under reverse voltage across the path wires; Zener diodes 2 are designed to turn on the corresponding thyristor 3 when the voltage is in a line above the threshold of the stabilizer. Diode 6 together with thyristors 3 serves to protect equipment depending on the polarity of the affecting voltage, i.e. either one of the thyristors 3, or the thyristor 3 and diode 6 are opened. The device operates as follows. When the voltage rises, for example, on the top wire above the threshold, when the Zener diode 2 closes, the latter opens and the control current begins to flow through the control transition of the corresponding thyristor 3, resulting in the opening of the thyristor 3. If the polarity of the affecting voltage is positive, semiconductor diode 6 and the lower thyristor 3 open. If the polarity of the influencing voltage is negative, the upper thyristor is triggered. 3. Similarly, the device operates with respect to the lower wire when the external voltage polarity changes. When protected from a dangerous current in the line, when this current rises above the permissible value, the LED (input circuit) of the thyristor optocoupler 1 opens and turns on the corresponding thyristor 3, thereby shading the protected device. If it is necessary to protect against dangerous currents of the field of polarity, one more thyristor optocouplers can be connected to the wires of the path, the output circuits of which can be used. turn on opposite shoulders. Thus, the proposed device, in comparison with the known, provides protection of electronic equipment not only against dangerous voltages, but also against dangerous currents, while retaining all the advantages of the circuit. The invention device to protect the communication line from overvoltage by aut. St. N 754563, characterized in that, in order to expand the functionality of the device, by simultaneously protecting against dangerous currents, an input of a thyristor optocoupler shunted by a resistor is connected in series to each wire of the path, and the output circuits of the optocouplers are connected in parallel to the zener diodes of the thyristor control circuits. Sources of information taken into account in the examination 1. USSR author's certificate N 754563, cl. H 02 H 9/04, 1978. V  A -.-- Oh V five II 4i eu