JPH0785610B2 - Ground switch for gas insulated switchgear - Google Patents

Description

The present invention relates to a ground switch for a gas insulated switchgear.

A gas-insulated switchgear (hereinafter referred to as GIS), which is configured by housing the circuit breaker body, disconnector body, busbar conductor, etc. in a metal container at ground potential filled with insulating gas such as SF ₆ gas. In order to ground the safety of the main circuit, that is, the main body of the circuit breaker, the main body of the disconnector, and the energized main circuit formed by connecting and disconnecting the bus conductors, a grounding switch is provided at a required place.

By the way, the main circuit of the GIS has a sealed structure as described above, so the main circuit resistance to check whether or not it maintains the specified performance is measured by the terminals of each device such as the circuit breaker body and disconnector body. Can not be done directly from outside the container. For this reason, two ground switches are used and the voltage drop method is used.

However, when using a normal grounding switch, there is a problem that a value including the resistance of the grounding switch is derived.

On the other hand, if the main circuit grounding circuit (current injection circuit) and the main circuit voltage measuring circuit are separated, the resistance of the grounding switch is not included.

In order to satisfy this, it is conceivable that the movable part and the voltage measuring terminal of the voltage measuring circuit are connected by a flexible electric wire. However, according to this configuration,
When the number of times of opening and closing is increased, there is a problem that the connecting portion of the electric wire may be fatigue-ruptured, or the flexible portion may be entangled with other parts to hinder or cut the operation. It is also conceivable to configure the voltage measuring circuit by slidingly contacting the flexible electric wire for the entire stroke of the opening / closing operation instead of the flexible electric wire, but there is a problem that the wear of the contact is accelerated.

By the way, the grounding switch is used in various places. For example, when it is used on the GIS line side as shown in FIG. 1, there is a case where a large current flows to the grounding circuit due to the induction from the line 101. It is dangerous to ground the ground wire 102 to the GIS container 3. Therefore, the ground wire 102 is routed to the ground point 103 where sufficient grounding is performed at the electric station.

Therefore, at the moment when the impedance of the grounding circuit becomes high and the movable contacts 8 and 21 are closed and grounded, the grounding terminal
A voltage close to the rated voltage of the main circuit 104 may be applied to 26a. At this time, in the unlikely event that the container 3 is flashed, a surge voltage will be generated in the surrounding equipment, and the equipment (for example, the disconnecting switch, the control circuit of the operation device of the earthing switch, etc.) will be damaged.

Therefore, in order to prevent such a situation, the ground terminal 26a is designed to maintain insulation strength. Specifically, since the countermeasure is taken by increasing the creepage distance of the insulating spacer 105, the insulating spacer 105 becomes relatively large.

CB is a circuit breaker, DS is a disconnecting switch, and CH is a cable head.

As described above, when the main circuit grounding circuit and the main circuit voltage measuring circuit are separated, the latter is also provided with the voltage detection conductor 27 at the portion drawn from the container 3, but even if there is no current-carrying capacity, the voltage detection conductor 27 is drawn from the insulating surface. Insulating spacers 106 having substantially the same size as the insulating spacers 105 in the conductor 26 are required, which has the drawbacks of increasing space and cost.

In addition, the charge voltage of the power cable or the charging voltage of the capacitor load may be grounded via the grounding switch. In this case as well, a voltage close to the rated voltage of the main circuit may be applied in the same manner as above. There is a problem that the insulating spacers for the grounding circuit and the voltage measuring circuit must be large.

The present invention has been proposed in view of the above points, and an object thereof is to separate the main circuit grounding circuit and the main circuit voltage measuring circuit, and further, in the former in which the latter is closed near the closed position, both circuits are The purpose is to provide a grounding switch for GIS that shares space and costs by reducing the space.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 2 shows one embodiment of the present invention, in which the inside of the main body container of GIS is filled with an insulating gas 2 such as SF ₆ gas at a predetermined pressure. 3 is an end container that closes the open end of the container 1 and also serves as an operation mechanism container for the ground switch 4 and the disconnector 5. Reference numerals 6, 7 and 8 are fixed contacts, sliding contacts and movable contacts of the earthing switch. The contactor 6 is supported by the container 3 through the main conductor 9 of the main circuit, the insulating spacers 10, and the mounting base 11 for the three phases arranged in the direction orthogonal to the plane of the drawing. The sliding contactor 7 is supported by the container 3 via a contactor stand 12 and an attachment plate 13 made of an insulating material and having three phases.

The movable contactor 8 is operated by an operating unit (not shown) connected to an operating shaft 17 via a connecting rod 14 made of an insulating material, a three-phase mounting metal fitting 15, and an operating lever 16. Reference numeral 18 is a guide for guiding the mounting hardware 15 to move linearly and is arranged between the phases. 19 is a stopper.

In this embodiment, the movable contactor 8 has a cylindrical shape, and the voltage detection movable conductor 21 is housed inside the insulating cylinder 20. A tip 21a of the conductor 21 is slightly projected from the tip of the movable contact 8 so that the conductor 21 comes into contact with the fixed-side voltage detection contact 22. Reference numeral 23 is a pressure contact spring. An auxiliary movable contact 24 is attached to the other end of the conductor 21 and protrudes from the side surface of the movable contact 8 at a right angle. An auxiliary fixed contact 25 for receiving the contact 24 is attached to the mounting plate 13.

Reference numeral 26 is a grounding lead conductor, and 27 is a voltage detecting conductor, which are integrally embedded in an insulating spacer 28 made of an insulating material such as epoxy resin. Reference numeral 29 is a connection conductor for connecting the conductor 26 and the contact base 12, and 30 is a connection conductor for connecting the conductor 27 and the contact 25 for voltage detection.

The ground terminal 26a of the lead conductor 26 is grounded by an insulated wire 102 to a ground point 103 by a ground network at an electric station.

34 is a shield, 35 is a main circuit lead-in conductor, and 36 is a main circuit lead-out conductor.

Further, although each component has three phases arranged in a direction perpendicular to the plane of the drawing, the description thereof is omitted.

The disconnector 5 has a fixed contactor, a sliding contactor, a movable contactor that slides into and out of contact with these, and is operated from the outside of the container 3, but the description thereof is omitted.

The grounding switch 4 opens when the disconnector 5 is closed and the main circuit conductors 35, 9, 36 are connected. In this state, the main circuit is energized.

The main circuit conductors 35 and 9 may be grounded by closing a circuit breaker (not shown), opening the disconnector 5, and then closing the grounding switch 4. As a result, the fixed contact 6, the movable contact 8, the sliding contact 7, the contact stand 12, the connecting conductor 29, the lead conductor 26, the insulated wire 102 for grounding, and the main circuit grounding circuit by the ground point 103 Grounding is performed.

The auxiliary contacts 24 and 25 come into contact with each other when the earthing switch 4 comes close to the closed position, that is, when the movable contact 8 and the fixed contact 6 come in contact with each other, and the conductor 21 and the contact 22 come into contact with each other. Therefore, in addition to the grounding circuit, a main circuit voltage measuring circuit including the spring 23, the contact 22, the conductor 21, the contacts 24 and 25, the connecting conductor 30, and the conductor 27 is formed.

The main circuit resistance can be measured by, for example, a circuit breaker CB as shown in FIG.
The grounded switches 4 and 4'that sandwich the measured sections a and b having the above are closed, and the insulated wires 102 and 102 'are removed from the ground terminals 26a and 26a' of the lead conductors 26 and 26 ', respectively. Then, the measuring power source D is connected to allow a current to flow, and the voltage between the voltage detecting conductors 27 is measured by the voltmeter V to obtain the resistance. In this way, the voltage between the conductors 27 is the same as the voltage between the sections a and b to be measured, and the resistance of the main circuit can be directly measured, so that a highly accurate check can be performed. That is, it is possible to measure only the main circuit resistance without including the contact portions of the grounding devices 4 and 4'and the resistance of the lead conductor.

In this embodiment, since the flexible electric wire is not used, fatigue cutting due to the opening / closing operation and the trouble that the flexible electric wire is entangled with other parts do not occur. Also, the sliding portion is minimized, so that the wear is small. It also requires less operating force.

Further, since the lead-out conductor 26 of the ground circuit and the voltage detecting conductor 27 of the voltage measuring circuit are lined up and integrally molded and the insulating spacer 28 is shared, the space and cost are reduced.

Although the insulating spacer 28 is provided for each phase in the above embodiment, three phases may be integrated, and in this case, the space can be further reduced.

It is also possible to provide the voltage detecting conductor 27 inside the lead conductor 26 by hermetically sealing the O-ring or by resin bonding.
In this case, compared to the illustrated embodiment, the instability of airtightness due to the use of a small O-ring or the instability from cracking to airtight leakage due to the adhesion of a small amount of resin is inevitable. Can be used satisfactorily.

As described in detail above, according to the present invention, not only the main circuit can be reliably grounded, but also only the main circuit resistance can be accurately measured, and the flexible wire is not required, and the structure is simple and highly reliable. , It is possible to provide a grounding device for GIS in which the insulating spacers of the main circuit grounding circuit and the main circuit voltage measuring circuit are shared and the space and cost are reduced.

[Brief description of drawings]

FIG. 1 is an electric diagram showing a conventional device, and FIG.
FIG. 3 is a side sectional view showing an embodiment, and FIG. 3 is an electric circuit diagram for explaining a main circuit resistance measuring method according to that of FIG. 6: Fixed contact, 7: Sliding contact 8: Movable contact, 20: Insulating cylinder 21: Movable conductor for voltage detection 22: Contact for voltage detection on fixed side 24: Auxiliary movable contact 25: Auxiliary fixed contact 26 : Lead-out conductor, 27: Voltage detection conductor 28: Insulation spacer

Claims (1)

[Claims] 1. A gas-insulated container in which a closed container is filled with an insulating gas and a main circuit conductor for energization connected in series through a circuit breaker is housed therein, and which is connected before and after the circuit breaker. In the grounding switch for switchgear, this grounding is performed by a fixed contact provided on the main circuit conductor, a movable contact that makes contact with and separates from the fixed contact, and a sliding contact between the movable contact and an insulator. A sliding contact attached to the mounting plate; a grounding lead conductor connected to the sliding contact and led out to the outside of the container in an insulated manner; A voltage detection movable conductor having a projecting tip, a voltage detection contact provided on the main circuit conductor with which the tip of the voltage detection movable conductor contacts, and a voltage detection movable conductor attached to the insulating mounting plate. Auxiliary provided at the rear end of the voltage detection movable conductor An auxiliary fixed contact with which the contact comes in contact, a voltage detection conductor which is provided independently of the auxiliary fixed contact from the circuit for grounding the main circuit via the grounding conductor and is insulated from the outside of the container, and A main circuit formed through the voltage detection movable conductor, comprising: a common conductor for drawing out a ground circuit lead-out conductor and a voltage detection conductor for the voltage measurement circuit, which are insulated and led out to the outside of the container. A ground switch for a gas insulated switchgear, characterized in that the voltage measuring circuit is configured to be closed near a closed position of a main circuit grounding circuit formed through the movable contactor.