CH634177A5 - Switching facility for high-voltage electrical current - Google Patents

Description

The invention relates to a switching installation for high voltage electric current. More particularly, it relates to an improvement made to a gas-insulated switching device.

Due to the increase in demand for electrical energy, there is a tendency to increase the voltage of electrical power transmission lines and electrical power transmission lines have already been built operating at a voltage of 500 to 800 kV .

Consequently, an electrical substation or switching station equipping an electrical power transmission line operating at such a high voltage occupies a large area. For example, if the line voltage is 500 kV, the required insulation distance between the three phases as well as the insulation distance from the ground, reach 8 meters, taking into account a certain safety margin. Accordingly, it is advantageous to use a gas insulated switchgear, that is, a switchgear in which the circuit breakers, circuit breakers, grounding switches and the elements analogues, forming part of an electrical substation, or switching station, are enclosed in metal receptacles, earthed and provided with insulation produced by means of a gas, for example sulfur hexafluoride, having high dielectric strength and excellent arc quenching properties.

The use of such a gas-insulated switching device makes it possible to reduce the area occupied by the installation by approximately 90% and to build this switching device in a compact form.

The isolation distance between a bus bar and a power bus cannot be reduced, both of which are electrically connected to the switchgear. In addition, a large number of insulators that insulate the respective bus bars in isolation must be of sufficient size and length to allow the required insulation distance to be obtained from the hanger frames of the bus bars.

The object of the invention is to provide a switching installation in which the properties of gas-insulated switching devices are fully exploited, this installation being able to be constructed in a compact and simplified form, allowing the removal of a pylon and in which the distance between the extreme terminals can be reduced.

For this purpose, the switching installation according to the invention, which comprises three gas insulated switching units, each of which comprises a circuit breaker, circuit breakers and earthing switches which are enclosed in metal housings placed to earth whose interior is filled with insulating gas capable of extinguishing the arc and which are associated with each other electrically and mechanically; protective cover terminals for connection to the outside of these switching units; and intermediate terminals with protective cover ensuring the connection of these switching units with supply bus bars, is characterized in that these switching units are arranged parallel to each other.

Preferably, a terminal with a protective cover is electrically and mechanically associated with a divergent bus bar which itself is electrically and mechanically connected with said switching units.

Also preferably, the installation further comprises a main bus bar, supported by pylons so as to be isolated; and supply bus bars connecting this main bus bar to one of said intermediate terminals with protective cover and connecting an electrical energy transport line to one of said terminals with protective cover.

Preferably, the gas capable of extinguishing the arc is an electro-negative gas, such as sulfur hexafluoride, and it is under a pressure of three to ten atmospheres.

In the case where the switching installation according to the invention is used in a three-phase electrical energy transport circuit, each of the phases must include a group of three gas-insulated switching units.

The invention will be better understood thanks to the detailed description which follows of a gas-insulated switching device of known type as well as of an embodiment of the gas-insulated switching installation, in accordance with the invention , with reference to the accompanying drawings in which:

Figure 1 is a side view of a gas-insulated switching apparatus, of known type;

Figure 2 is a plan view of part of the apparatus shown in Figure 1, viewed in the direction of the line n-n;

Figure 3 is a schematic diagram showing the circuit of phase "T" of the apparatus of Figure 1;

Figure 4 is a schematic diagram showing the circuit of phase "T" of the installation according to the present invention;

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634,177

Figure 5 is a plan view showing an embodiment of the switching installation, gas insulated, according to the invention;

Figure 6 is a side view of an embodiment of the gas-insulated switching installation according to the invention, partially shown in longitudinal section;

Figure 7 is a side view of the installation shown in Figure 5, seen in the direction of line L-L of this figure;

Figure 8 is a side view of the installation shown in Figure 5, seen in the direction of the line M-M of Figure 5; and FIG. 9 is a side view of this same installation, observed in the direction of the line N-N in FIG. 5.

As can be seen in FIG. 1, an installation for distributing and switching electrical current, of known type, covered with a metal case, comprises three gas-insulated switching units 10, 11, 12 arranged in series. The gas-insulated switching unit 10 consists of a circuit breaker 13 on which is mounted a protective cover terminal 20 and it comprises a grounding switch 15 and a circuit breaker 16 each end of which is provided with a current transformer 17. One of the current transformers 17 is connected to the circuit breaker 13 and the other current transformer 17 is connected to a circuit breaker 18. The circuit breaker 18 is connected to a protective cover tank containing a grounding switch 15.

The gas insulated switching unit 11 consists of a circuit breaker 16, two circuit breakers 18 and two current transformers 17. The arrangement of the gas insulated switching unit 12 is identical to that of the switching unit. gas-insulated switching unit 10. The gas-insulated switching unit 11 is electrically and mechanically associated with the gas-insulated switching units 10 and 12, by means of the protective cover tank 19. A protective cover terminal 20 is installed above the circuit breaker 13. An intermediate terminal with protective cover 21 is installed above the tank with the protective cover 19. Each of the gas-insulated switching units 10 and 12 is connected via the terminal with protective cover 20 to a main busbar 22, by means of a supply busbar 23. Each intermediate terminal with protective cover 21 is connected to the electric power transmission line 24 by means of a supply busbar 25 . The electric power transmission line 24 and the supply bus bar 25 are suspended from insulators 26 which are themselves hooked to pylons 27. The pylons 27 are connected together by means of a connection wire. aerial land 28.

In the case of a 500 kV electric power transmission line, the distance B between the main bus bar 22 R and the other main bus bar 22 T is 40 meters.

Figure 2 is a plan view of the installation shown in Figure 1. The isolation distance A between the three respective phases reaches 8 meters, taking into account a certain safety margin.

Consequently, the surface occupied by the electrical substation of the 500 kV class is greater than 720 square meters.

The circuit diagram shown in Figure 3 illustrates a switching device corresponding to the A's circuit breaker busbar system.

One of the main bus bars 22 is connected to one of the electric power transmission lines 24 by means of a circuit breaker 16 which is provided with two circuit breakers 13 and 18, arranged on both sides other of the circuit breaker 16. The two electric power transmission lines 24 are connected together by means of the circuit breaker 16, each end of which is provided with a circuit breaker 18. The bus bar system with circuit breaker A is useful for stabilizing the transmission of electrical energy from the main busbar 22 to the electrical power transmission lines 24.

FIG. 4 represents a circuit diagram of an electrical substation or switching station, which is represented in FIG. 5, in accordance with the present invention.

Although the parts corresponding to the three phases T, S and R are shown in FIG. 5, only the part corresponding to the phase T is described with reference to FIG. 4 since! O the parts corresponding to the other phases S and R are arranged in the same way.

An electrical power transmission line 40 is connected to a main busbar 42, by means of a terminal with protective cover 44, circuit breakers 18, current transformer 15, circuit breaker 16 , another current transformer 17 and an intermediate terminal with protective cover 45. Earthing switches 15 are arranged on the opposite sides of the circuit breakers. Earthing switches are used to ground the circuit, for safety reasons, when testing the substation or electrical switching station.

An electric power transmission line 41 is connected to a main busbar 43 by means of a terminal with protective cover 46, circuit breakers 18, an intensity transformer 17, circuit breakers 16, another current transformer 17 and an intermediate terminal with protective cover 47. The electrical energy transmission line 41 is also connected, in the same way, to the electrical energy transmission line 40 .

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FIG. 5 illustrates an embodiment of an installation corresponding to the diagram shown in FIG. 4. The gas-insulated switching units 50, 51, 52 are arranged so that the circuit breakers 18, the circuit breakers 16, the intensity transformers 35, the grounding switches 15 and the like are enclosed in grounded metal boxes which are filled with SF6 gas, at a pressure of three to ten atmospheres. The gas-insulated switching unit 51 is electrically and mechanically associated 40 with the gas-insulated switching units 50,52, via the divergent bus bars 53. The terminals with protective cover 44,46 are installed above the terminal of the divergent bus bars 53. The intermediate terminals with protective cover 45, 47 are arranged above the circuit breakers 18. 45 The arrangement of the gas-insulated switching units 51, 52 is identical to that of the switching unit insulated with gas 50. The terminal with protective cover 44 is connected to the electric power transmission line 40 by means of a supply bus bar 54. The terminal with protective cover 46 is connected to the line of transmission of electrical energy 41 via a supply bus bar 54. The intermediate terminal with protective cover 45 is connected to the main bus bar 42 via a supply bus bar 54. The bo an intermediate protective hood 55 is connected to the main busbar 43 by means of a supply busbar 54. The electric power transmission lines 40,41 and the supply busbar 54 are attached to insulators 26 which are themselves suspended from pylons 27. Each pylon 27 is 60 connected to an overhead ground wire 28.

In the case of an electric power transmission line of the 500 kV class, despite the fact that the insulation distance between the three respective phases reaches 8 meters, taking into account a certain safety margin, the distance D is only 65 meters from 20 meters thanks to the fact that the gas-insulated switching units 51.52 are placed between the respective phases T and S. The distance E between the terminals with protective cover 44.46 is 20 meters taking into account a certain safety margin.

634177

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As a result, the area occupied by the 500kV class electrical substation is approximately 400 square meters.

FIG. 6 illustrates, in detail, the arrangement of the terminal with protective cover 47, of the gas-insulated switching unit 52, etc.

The gas insulated switching unit 52 is arranged inside cylindrical metal boxes 55, 56, 57 which are held above the base of the installation 58 by means of feet 59, 60. These metal boxes are filled with SF6 gas, at a pressure of three to ten atmospheres. A plurality of damping gas circuit breaker units 61, arranged in groups of two units, are placed in series in the first cylindrical housing 55. A movable member, forming part of a group of circuit breaker units 61 , is supported inside the housing 55 by a hollow insulating cylinder 62 and it is controlled and set in motion by means of an insulating rod (not shown) which passes through the insulating cylinder 62.

The circuit breaker control mechanism is identified by the reference numeral 63. The control mechanism 63 and the insulating rod are mechanically associated with one another so as to allow the opening or closing of the circuit breaker.

The reference numeral 64 designates a control orifice provided in the housing 55, this orifice being hermetically closed by means of a cover 45 provided with an absorbent member 66. An insulating spacer in the form of a disc 67 is supported in the outer peripheral part 67A and it is hermetically closed between a flange 56A disposed at one end of the housing 56 and a flange 57A disposed at the other end of the housing 57. A flange 56B, disposed at the other end of the housing 56 is hermetically sealed on a flange 55B placed at one end of the housing 55. Another insulating spacer in the form of a disc 67 is also supported by the external peripheral part 67A and hermetically closed between a flange 57B, placed at the other end of the housing 57, and a flange 70A disposed at one end of the housing 70. In addition, a conductor 72 is placed in the central part of the spacer 67 and this conductor is connected to the u ne of the ends of the circuit breaker unit 61, by means of an electrically conductive member 72 and, at the other end, it is connected by means of a pipe 73 to the circuit breakers 13, which will be described later. Each spacer 67 separates the housing 57 from the housings 55, 56 and also from the housing 70, in a gas-tight manner.

The left part of the circuit breaker unit 61 is electrically connected to the circuit breaker 18.

Circuit breakers 74 are placed inside the metal cylindrical housings. The circuit breaker 74 comprises a fixed contact 74A, placed at one end of a conductor 75 supported by an insulating spacer in the form of a disc 67, and a movable contact 74B. The movable contact 74B is in contact with an electrically conductive member 76 which also provides the support function for this movable contact and which includes a current conductive contact (not shown). The electrically conductive member 76 is supported by the insulating spacer 67, by means of a conductive piece. The movable conductor 74B is arranged so as to be controlled and set in motion, in the direction of the arrow "P", shown in the drawing, by means of a control mechanism 78 mounted on the outer surface of the housing 70 by the through an insulating rod 79. An orifice 80 is formed in the box containing the control mechanism, in order to allow the latter to be controlled, this orifice being hermetically closed

by means of a cover 41. A control lever 42 is actuated and set in motion by the control mechanism 78.

A grounding switch 15 is installed on the

5box 70 and its earthing contact 42 is arranged

so as to be closed when the electrically conductive member 76 is in the open position. The earthing contact 42 is actuated by means of a control mechanism 83.

A gas-insulated busbar 84 comprises a cylindrical metallic xo box 57 and an electrically conductive member 73 arranged concentrically inside the housing 57. The gas-insulated busbar 84 is surrounded, concentrically, by the current transformer 17. The current transformer 17 consists of a solenoid 90 and a housing 91 which contains the solenoid 90 and which is mounted on a pedestal 92.

The lower end of a central conductor 93, which passes through the intermediate terminal with protective cover 47, is connected to the conductor 75 which passes through a disc-shaped spacer 67. The conductor 75 is placed in the housing 2o70 and it is electrically and mechanically connected to the fixed contact 74A of the circuit breaker 74.

The reference numeral 94 designates a protective ring which is placed concentrically with respect to the base of the protective cover 47. The disc-shaped insulating part 67 is supported in such a way as to be hermetically closed to the external peripheral part 67A between a flange 70B, placed at one end of the housing 70, and a flange 95A, placed at one end of the housing 95. The housing 95 is disposed between the cover 47 and the cylindrical metal housing 70.

3o The insulation characteristics of the circuit breaker 16 are improved by bringing the gas pressure in the housing 55 to a value greater than that prevailing in the housing 57 or the housing 70.

Although the protective cover 47 is shown, in the embodiment which has just been described, in the form of a gas-insulated cover, one could also use in the installation according to the present invention a filled protective cover oil, in particular a protective cap of the condenser type filled with oil, instead of the gas-insulated protective cap. 40 The use of gas-insulated switching units makes it possible to stabilize the transmission of electrical energy from the main bus bars 42 and 43, to the electrical power transmission lines 40 and 41. For example, when the bus bar main 42 is broken, the gas iso-45 switching unit 50 (Figure 5) is switched off and, therefore, the electrical energy is transmitted from the main busbar 43 to the transmission lines d electrical energy 40 and 41. When the main busbar 43 is broken, the gas-insulated switching unit 52 (Figures 5 and 6) is turned off and, therefore, electrical energy is transmitted from the main busbar 43 to the electric power transmission lines 40 and 41. When the main busbars 42 and 43 are broken, the gas-insulated switching units 50 and 52 are switched off and, consequently, 55 , transport lines of electrical energy 40 and 41 are connected to each other.

In the above description, no mention has been made of organs of the usual type, such as voltage detectors, 60 spark gaps, etc. However, it is clear that such elements would be incorporated, the usual way, in the electrical energy switching installation covered with a metal case which has just been described.

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3 sheets of drawings

Claims (8)

634,177 1. Switching installation, gas insulated, comprising three switching units, gas insulated, each of which includes a circuit breaker (16), circuit breakers (18) and grounding switches (15), which are enclosed in earthed metal boxes, the interior of which is filled with insulating gas capable of extinguishing the arc and which are associated with each other, electrically and mechanically; protective cover terminals (44,46) for connection to the outside of these switching units; and intermediate terminals with protective cover (45,47) ensuring the connection of these switching units with supply bus bars (54), characterized in that these switching units (50,51,52) are arranged in parallel between them. 2. Installation according to claim 1, characterized by the fact that a protective cover terminal (44) is electrically and mechanically associated with a divergent bus bar (53) which is itself electrically and mechanically connected with said switching units. 2 3. Installation according to claim 1 or 2, characterized in that it further comprises: a main bus bar (42,43) supported by pylons so as to be isolated; and supply bus bars (54) connecting this main bus bar to one of said intermediate terminals with protective cover (45, 47) and connecting a line for transporting electrical energy to one of said terminals with protective cover ( 44.46). 4. Installation according to one of claims 1 to 3, characterized in that the gas capable of extinguishing the arc is an electronegative gas and that it is under a pressure of three to ten atmospheres. 5. Installation according to claim 4, characterized in that said electronegative gas is sulfur hexafluoride. 6. Installation according to one of claims 1 to 5, for a three-phase electrical energy transport circuit, characterized in that it comprises, for each of the three phases, a group formed by three of said switching units. 7. Installation according to one of claims 1 to 6, characterized in that the circuit breaker and the circuit breakers are placed inside the separate boxes insulated from each other by waterproof membranes. 8. Installation according to one of claims 1 to 7, characterized in that the opposite ends of a gas insulated bus bar (84), connecting a terminal with protective cover to a gas insulated switching unit, are provided waterproof insulating spacing parts whose interior is filled with gas.