SU516146A1 - Device to protect a wired communication line from overvoltage - Google Patents

Description

The invention relates to the field of communications installations from hazardous voltages caused primarily by the influence of power plants, as well as atmospheric overvoltages.

Devices are known in which gas-filled dischargers and drainage coils 1 are used to protect against significant stresses arising relative to the ground.

It is known, in particular, a device for protecting a wired communication line from overvoltages, containing arresters connected between the communication wires to be protected and ground, as well as a drainage coil connected between these wires 2.

The known devices are constructed in such a way that the protection of the communication line is carried out only if the resulting overvoltages exceed the threshold of operation of the corresponding bit. However, in a number of cases it is necessary to ensure the elimination of overvoltages lower than the triggering voltage of the arresters, for example, when protecting communication lines on concrete supports from the dangerous influence of high-voltage power lines (OHL).

The normalized, allowable voltages with a short circuit disconnect time on VL 0.6 s and above are 120 V (rms value). This voltage is significantly less than the operating voltage of the specified arresters, amounting to 280-350 „.„ „„, ..,

200-250 V depending on

type of discharge (RB-280, R-350, ZR 350). Ensure the trigger is triggered when

overvoltages smaller than the threshold between the main (protective) electrodes can be made using gas-filled arresters with nodging electrodes; and, but they are energized by means of a pop-up transformer. However, such a solution should not be applied to protect communications, since the wires of these lines must be strictly symmetric with respect to the ground, and the permissible leakage resistance is measured by megohms. Under these conditions, it is not possible to ensure an effective ignition of the glitter.

The aim of the invention is to eliminate overvoltage on the wires of the communication line and

providing sample dischargers at voltages. The 1 lower threshold.

This goal is achieved by the fact that the device additionally contains a step-up transformer, and the arresters are made with ignition electrodes, the transformer primary winding being connected between the midpoint of the drain coil and ground, and the secondary winding through the limiting resistances to the ignition electrodes.

The scheme of the device is shown pa drawing, where 1 - wires of the protected line; 2 - dischargers; 3 - drainage coil; 4 - transformer; 5 - resistors; 6 - capacitors.

The arresters 2 are designed to divert a pair that exceeds the allowable voltage from the wires of the communication line. A three-electrode discharge can be used, for example, of the P-35 type.

A drainage coil 3, connected between the protected cables, is intended for balancing the line.

Transformer 4 is turned on by winding a higher voltage on the igniter electrodes of the arrester 2 and is designed to increase the voltage applied to the discharge.

Resistors 5 are included in the circuits of each pair of ignition electrodes to eliminate the possible reduction of voltage on the secondary winding of transformer 4 when gas is broken between the ignition electrodes of one of the arresters on this circuit.

The capacitors 6 are connected between each end of the drainage coil and the wires to be protected when it is desired to monitor the state of the circuit to be protected by direct current.

The device works as follows.

When voltage is applied to the protected wires 1 against the ground, it will be applied through the windings of the drainage coil 3 with negligible attenuation to the primary winding of the transformer 4.

The windings of the drainage coil are symmetrical and the magnetic fluxes in the core cancel each other out.

The transformation ratio n of the transformer 4 is chosen so that the voltage on the linear voltage leads to earth and that arising on the secondary winding of the voltage nU is sufficiently large to break the gap between the ignition electrodes of the arresters, for example, with a margin of at least twice.

After the ionization of the internal space of the discharge, the gaps between the main electrodes are punched at a voltage of QT from tenth to several tenths of the nominal response between them. This ensures the elimination of overvoltages on the linear wires.

To reliably trigger dischargers

branch inductance on both wires

magnetizing transformer 4 must

be significantly higher than shoulder inductance

drainage rolls. 3

In the event of atmospheric overvoltages, with a relatively large amplitude and a steep front, the main electrodes of the arresters 2 will immediately penetrate.

Thus, the device provides reliable protection both at voltages lower than the trigger threshold, and the gentle front of the overvoltage wave (e. S., Induced by overhead lines), and at atmospheric overvoltages. The use of the proposed device does not degrade the symmetry of the communication circuit.

Claims (1)

Invention Formula A device for protecting a wire communication line from non-non-generic, containing arresters connected between the protected wires of the communication line and ground, as well as a drain coil connected between these wires, characterized in that, in order to reduce the device operation voltage, it additionally contains a step-up transformer, and the arresters are filled with ignition electrodes, the primary winding of the transformer is connected between the midpoint of the drainage coil and the ground, and the secondary is connected through limiting sleep otivleny to igniter electrodes arrester. Sources of information taken into account in the examination: 1 Rules for the construction and repair of overhead lines and radio transmission networks, part IV, pp. 24, 60, 1971. 2 Auth. St. № 127284, M. CL. H 02 H 9/04.