SU987826A1 - Device for protecting cable communication line - Google Patents

Description

The invention relates to relay protection and can be used to protect cable lines, due to the influence of external electromagnetic fields created by various sources (PI, contact network, lightning discharges.

A device for protecting a communication line with gas-filled gaps is known, including 1X between the cable cores and the sheath within the amplification section. When exposed to an external electromagnetic field between the core and the shell arise. large voltages leading to triggering of the arrester. The voltage between the core and the shell is reduced to a safe value of 1.

However, after the cessation of the effect of the electromagnetic field, the discharge remains in the on state, as the current of the remote power supply flows through. This leads either to a disruption of communication due to the shunting of the cores by arresters, or to overload and disconnection of the remote supply circuits.

Closest to the present invention is a device that contains reed switches in wallless diaphragm filled with ionizing gas, connected between the wire and ground. The windings of the reed switch relays are included in the rupture of the command connection. When dangerous voltages appear between the wire and ground, the reed switch operates like a normal gaiter, and when a large current is generated in the wire, the contact triggers like a relay. In either case, the protection device (reed switch) is triggered by an overvoltage impulse in the communication wire. If, however, a constant remote power supply current is transmitted through the wire, then it, through the relay winding, may trigger the reed switch 2.

Thus, the device has the same drawback as in the case of the application of the arrester. Namely zagdaty chain with reed. the relay will be turned on by remote powering, and the inductance of the relay coil in the communication wire reduces the spectrum of frequencies transmitted by wire.

The purpose of the invention is to reduce the number of devices for the work of the protected communication line.

Claims (2)

This goal is achieved by the fact that in a cable protection device containing a reed relay, the closing contacts of which are connected between the cores and the shell, the control coil of this relay is included in the cable sheath break and its disconnecting contacts are split between the cores contacts and source of remote power supply of the protected line. The drawing shows a device diagram. The device contains a coil 1 of a control of a reed switch, which is included in the dissection of the sheath 2 of a communication cable. Breaking contacts 3 of the relay are included in the dissections of the cores of the 4 cable, and closing contacts 5 are between the conductors 4 and the shell 2. Contacts 3 are connected between the remote power source (not shown) of the communication line and contacts 5. The device operates as follows. In the absence of current in the sheath 2, the cable cores are restored and working currents and currents of remote power flow through it.When an external electromagnetic field is applied to the cable, a current flows through the sheath and coil 1 of the relay, a magnetic field and voltage appear inside the coil Thus, the current in the shell, which is the cause of the occurrence of overvoltages in the protected core circuit, triggers protection. At the same time, the cores in the cable are broken and simultaneously closed on the shell. The core gap does not overload the remote circuits. . The power supply, and the 3-looping with a shell reduces the voltage at the disconnection of the tGM reed switch and on the conductors. The number of turns of the coil determines the pickup current, and its inductance is so small that it does not lead to a noticeable increase in communication between the living and the shell. The invention has the following advantages: its implementation is simple and does not require scarce components, the protection device practically does not limit the band of transmitted frequencies through the cable and when it is triggered, the remote power supply does not disconnect, which ultimately increases the reliability of communication. Claims An apparatus for protecting a cable link, comprising a reed switch, which contacts are connected between the conductors and the shell, characterized in that, in order to reduce the device’s impact on the link, the control coil of the relay is inserted cable, and its disconnecting contacts - in the dissections lived between the place where the closing contacts were turned on and the remote power source of the protected line. Sources of information taken into account during the examination 1. Mikhailov M.I. and others. Protection of communication structures against hazardous and interfering INFLUENDS. M., Sw., 1978, p. 250-252. 2. US patent 3858089, cl. H 02 H 3/10, published. 1974 (prototype). ////// 7 // L ///////////