RU2668220C1 - Connection diagram for fuse network for protecting cells of switch gears - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electrical engineering and can be used to protect the cell of switch gears in 6–35 kV networks. Voltage measuring transformer and the non-linear overvoltage suppressor are connected to the mains via a common fuse, designed to protect the voltage measuring transformer and the non-linear surge suppressor.

EFFECT: technical result is to provide protection against overload and short-circuit currents with one common fuse and a voltage measuring transformer and an overvoltage limiter non-linear without changing the dimensions of the switchgear cell, as well as providing the possibility of determining the operation of a common fuse for the absence of indications of devices included in the circuit of the measuring voltage transformer.

1 cl, 2 dwg

Description

The invention relates to the field of electrical engineering and can be used to protect cells of complete switchgear in networks of 6-35 kV.

An analogue is the connection circuit to the mains fuse for protecting the voltage measuring transformer (ITN) installed in the cell of the complete switchgear (KRU) together with a non-linear surge suppressor (OPN) connected to the network without a fuse (Imanov G.M., Khalilov F.Kh. ., Tadzhibaev AI Methodology for the selection of non-linear surge suppressors, Publishing House of the Perm Energy Institute for Advanced Studies of the Ministry of Fuel and Energy of the Russian Federation, St. Petersburg, 2000, p. 7, paragraph 3 bottom).

A disadvantage of the analogue is that the arrester is not protected against overload currents during prolonged quasi-stationary (temporary) overvoltages in the network and other abnormal operational influences, as well as from short circuit currents due to internal arrester damage, while arrester damage leads to serious electrical equipment failures in the networks and power supply systems.

The prototype is a circuit for connecting a fuse to the network to protect the arrester installed in the switchgear cell in conjunction with an ITN, which is protected by its fuse, i.e. two fuses are installed in the circuit (Imanov G.M., Khalilov F.Kh., Tadjibaev A.I. Methodology for the selection of nonlinear surge arresters. Publishing house of the Perm Power Engineering Institute for Advanced Studies of the Ministry of Fuel and Energy of the Russian Federation, St. Petersburg, 2000 , p. 7, paragraph 2 below).

The disadvantage of the prototype is that the fuse to protect the arrester can be detected by maintenance personnel only during inspection. In this case, until the cell is inspected, the electrical equipment remains unprotected from switching and lightning surges.

In addition, the installation of a fuse for the protection of an arrester and a fuse for protecting an ITN in a small-sized cell of modern complete switchgears is difficult, or requires a change in the dimensions of the cell.

The objective of the invention is to develop a connection circuit to the fuse network to protect the cells of the complete switchgear, which eliminated the disadvantages of the analogue and prototype.

The technical result is the provision of the possibility of protection against overload and short circuit currents by one common fuse and a voltage measuring transformer and a non-linear overvoltage limiter without changing the dimensions of the switchgear cell and with the possibility of determining the common fuse tripping due to the absence of instrument readings included in the voltage measuring transformer circuit.

The technical result is achieved by the fact that in the circuit of the fuse for protecting the cell of the complete switchgear comprising a voltage measuring transformer and a non-linear surge suppressor, connected to a fuse according to the present invention, the voltage measuring transformer and a non-linear surge suppressor are connected to the network through a common fuse, made with the possibility of protection of the measuring voltage transformer and surge suppressor nonlinear.

The invention is illustrated by drawings, where in FIG. 1 shows the proposed circuit for connecting a fuse to the circuit of the switchgear, and in FIG. 2 shows the design of a fuse configured to protect a voltage measuring transformer and a non-linear surge suppressor.

In FIG. 1 numbers indicate:

1 - network;

2 - measuring voltage transformer TV;

3 - surge suppressor nonlinear arrester;

4 - fuse F, configured to protect the measuring voltage transformer and non-linear surge suppressor.

In FIG. 2 numbers indicate:

5 - insulating tube;

6 - contact cap;

7 - an intermediate washer;

8 - fusible insert;

9 - ceramic core;

10 - bandage;

11 - quartz sand;

12 - cover.

The connection diagram of the fuse 4 network for protecting the switchgear switchgear cell v includes a voltage measuring transformer 2 and a non-linear surge suppressor 3 connected to the fuse 4.

The difference of the proposed circuit is that the measuring voltage transformer 2 and the non-linear surge suppressor 3 are connected to the network 1 through a common fuse 4, configured to protect the voltage measuring transformer 2 and the non-linear surge suppressor 3.

The fuse 4 for protecting the measuring voltage transformer 2 and the non-linear 3 surge suppressor 3 has a cartridge in the form of an insulating tube 5 reinforced with cement with contact caps 6.

A fusible insert 8 is placed in the cartridge, made of one or several parallel wires with the ability to pass switching and lightning impulse currents without tripping, as well as disconnect overload and short circuit currents with the ability to determine the tripping by the absence of instrument readings included in the voltage measuring transformer 2 circuit.

The wire is wound on a ceramic core 9 and fixed with the possibility of replacement on the intermediate washer 7, soldered to the bandage 10 on the ceramic core 9.

The tube 5 is filled with quartz sand 11 with the possibility of extinguishing the arc when the fuse box 8 burns out, is closed by covers 12 and hermetically sealed.

The connection diagram to the fuse network for the protection of the switchgear cubicles is as follows.

In normal mode, non-linear 3 and a voltage measuring transformer 2, which are under operating voltage, flow through the overvoltage limiter by a fraction of milliamperes, which does not affect fuse 4, which transmits rated currents measured in amperes without tripping.

When switching or lightning overvoltages occur, the current through the non-linear 3 overvoltage limiter in the microsecond time range increases to several kiloamperes, so the diameter and number of parallel fuse-links 8 of fuse 4 is selected so as to withstand lightning and switching currents without tripping.

With quasi-stationary overvoltages, the resistance of the non-linear 3 overvoltage limiter decreases, and the current flowing through it increases.

In order to maintain its thermal stability during prolonged quasi-stationary overvoltages, and other unnormalized influences, the diameter and number of parallel fuse-links 8 of fuse 4 are selected so as to disconnect the overload currents.

In the short circuit mode, the fuse insert 8 of the fuse 4 burns out along the entire length while maintaining the breaking capacity of the fuse 4, protecting the measuring voltage transformer 2 and the non-linear 3 overvoltage limiter in case of internal damage, while the operation of the fuse 4 can be determined by the absence of readings into the circuit of a voltage measuring transformer 2.

Thus, the use of the present invention will provide the ability to protect against overload and short circuit currents by one common fuse 4 and a voltage measuring transformer 2 and a non-linear 3 overvoltage limiter without changing the dimensions of the switchgear cell, and also provide the ability to determine the operation of the common fuse 4 by the absence of instrument readings into the circuit of a voltage measuring transformer 2.

The use of a fuse in the proposed circuit to protect the measuring voltage transformer and non-linear surge suppressor is possible in organizations and network companies serving; substations and distribution networks of 6-35 kV and implies a significant economic effect from reducing interruptions in power supply to consumers and extending the service life of electrical switchgear equipment.

Claims (1)

A fuse connection diagram for protecting the switchgear switchgear cell, comprising a voltage measuring transformer and a non-linear surge suppressor connected to a fuse, characterized in that the voltage measuring transformer and a non-linear surge suppressor are connected to the network through a common fuse configured to protect the voltage measuring transformer and non-linear surge suppressor.

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