SU624337A1 - Device for overvoltage protection of high-voltage network - Google Patents

Description

The invention relates to the field of electrical engineering and is used to protect electrical equipment of high-voltage electrical networks from overvoltages.

Known protection devices against prose and switching overvoltages are included in the power systems between the phase conductor and ground.

Such devices contain spark gaps, which penetrate when a dangerous voltage is generated on the conductor to isolate electrical equipment, and the energy of the wave is diverted to the ground. When spark gaps are triggered, a short-circuit in the network arises, which is turned off by the gas generator tube of the tubular arrester or by the power system switch.

A short circuit in the power system does not occur if the non-linear resistance is switched on in series with the spark gap in the overvoltage protection device.

Valve arresters containing spark gaps and nonlinear resistances with a high degree of nonlinearity of 1.2J are also known.

The use of such a resistance, which has a small value when overvoltage waves occur and a large one after their passage, leads to the limitation of the accompanying current of the industrial frequency to the value that is turned off by successively connected spark gaps.

The nonlinear impedances used in valve gaps have insufficient throughput. This does not allow to improve the protective characteristics of arresters by reducing the number of series-connected nonlinear resistance disks and spark gaps, since an increase in the accompanying current leads to a decrease in the service life of the armature.

Claims (2)

The aim of the invention is to improve the protective characteristics of an overvoltage protection device and increase the reliability of jsro operation. This is achieved by the fact that a device for protection against overvoltages of a high-voltage electrical network, containing a valve arrester, one output of which is connected to the mains wire, is equipped with an additional valve (m, one output of which is connected to the same network wire, and a two-winding transformer, moreover, the second terminals of said valve arresters are each connected to the terminals of different transformer windings, while the second terminals of these windings are grounded, The drawing shows the circuit of protection device about The device contains valve dischargers 1 and 2, connected to the wire 3 of the network, and the windings 4 and 5 of the transformer wound on a common core 6. When approaching the device overvoltage waves, due to the natural dispersion of discharging voltages of dischargers Initially, only one discharge (for example, discharge 1) is triggered. The current flowing through discharge 1 and winding 4 results in a magnetic flux in the core 6, resulting in a voltage across the winding 5 of the transformer of the opposite sign with respect to the voltage on the wire 3.. This leads to an increase in the voltage at the spark gaps and to the operation of the arrester 2. At the same time, the current flowing through discharge 2 and the winding 5 of the transformer detects a magnetic flux equal to the magnitude, but directed opposite to the current generated by the current in the winding 4. The total magnetizing flux of the core 6 is close to zero. The transmissive streams coupled to the winding of the transformer generators 4 and 5 create inductive resistances of the windings less than the resistance of magnetization and much less than the value of the non-linear resistance of the dischargers 1 and 2. The scatter of the volt-ampere characteristics of the non-linear resistance of the arresters does not cause a noticeable unequal current of the current Since the different voltages arising in this case on the windings 4 and 5 of the transformer, lead to the equalization of currents in the arresters. The magnetic flux of the scattering closing through the windings 4 and 5 with the flow of equal currents in them, and the absence of the magnetic flux of the magnetization of the core 6 determine the low inductive resistance of the windings and slightly degrade the protective characteristics of each discharge, however, the use of two parallel arresters. Improving the protective characteristics of the device reduces the magnitude of dangerous lightning and switching overvoltages. in high-voltage electrical systems, to reduce the level of isolation of power transformers and other electrical equipment of systems, to reduce the cost of construction and to increase the service life and reliability of the protective device. Claims An overvoltage protection device for a high-voltage electrical network, comprising a valve discharge, one output of which is connected to a network wire, characterized in that, in order to increase the reliability of its operation, it is provided with an additional valve discharge, one output of which is connected to the same to the network wire, and a double-winding transformer, repeat the conclusions of the specified valve arresters each connected to the terminals of the various transformer windings, while the second terminals of these windings are Lena. Sources of information taken into account in the examination: 1. Dolginov, A.I. Perenapr $ 1 in electrical systems, SEI, 1962. 2.Shishman, D.V., et al., High Pressure Voltage Valves, Energie, 1971.