CN1237680C - Sleeve-type support insulators and sleeve-type current transformers for air-insulated medium-voltage switchgear enclosed by metal enclosures - Google Patents

Abstract

The bushing insulator (DFS) and the bushing-type current transformer (DSW) have a rectangular bushing hole (DFO) that is staggered outward forming a stair step pattern, to which a receiving part (AFT) is connected, said receiving part being disposed crosswise in relation to said hole and being preferably fitted with a round cross sectional structure having a conductor terminal (LTA) pointing outward to the top side. The conductor terminal is connected in an electrically conductive manner to a counter-contact (GKT) by means of a primary conductor (PLT), whereby the bushing hole (DFO) and the receiving part (AFT) form part of a common cast resin body (GHK) and said cast resin body (GHK) has an external control electrode (SEA) molded into the cast resin surrounding the latter in a U-shaped manner in the front area of the bushing hole (DFO). The cast resin body is provided with an inner control electrode (SEI) that is molded into the cast resin and shields the bushing hole (DFO) in the form of a plate in the boundary area between the bushing hole (DFO) and the receiving part (AFT).

Description

Sleeve-type support insulators and sleeve-type current transformers for air-insulated medium-voltage switchgear enclosed by metal enclosures

technical field

The invention relates to a sleeve-type support insulator and a sleeve-type current transformer for air-insulated medium-voltage switchgear enclosed by a metal casing, each of which is arranged on a support plate and is detachable from the support plate ground connection.

Background technique

Bushing insulators and bushing current transformers are used in medium voltage switchgear to establish electrical connections between busbars or generally between cable terminals and switchgear. In addition, sleeve-type current transformers are used to monitor the current ratio of each phase of the medium-voltage switchgear. Not only the sleeve-type support insulator, but also the sleeve-type current transformer is designed so that it can meet the mechanical requirements in terms of bearing capacity and meet the electrical requirements in terms of its breakdown strength.

Contents of the invention

The technical problem to be solved by the invention is to design sleeve-type support insulators and sleeve-type current transformers for high measuring voltages, for example up to the range of 24 kV, which generally do not exceed what has hitherto been determined for such devices for lower voltages structural volume.

According to the present invention, above-mentioned technical problem is solved by following technical feature:

1.1 The sleeve-type support insulator and the sleeve-type current transformer each have a rectangular sleeve hole that is stepped outward on the front side,

1.2 Connected to the sleeve-type through-hole is a connecting part arranged perpendicular to it, preferably with a circular cross-sectional shape, on which there are wire terminals leading outwards,

1.3 The wire terminal is electrically connected to a static contact through a primary wire,

1.4 The sleeve-type through-hole and wiring parts are part of the same cast resin body,

1.5 the cast resin body has an external control electrode cast in cast resin in a U-shape surrounding the through hole at the front side region of the sleeve-type through hole,

1.6 The casting resin body is provided with a disc-shaped internal control electrode cast in the casting resin at the interface between the sleeve-type through hole and the wiring part to shield the sleeve-type through-hole.

In addition to using a stepped structure for the sleeve-type through hole to lengthen the leakage path, two additional control electrodes, namely a U-shaped external control electrode and a disc-shaped internal control electrode, are added to improve the sleeve-type support insulator and the sleeve-type current mutual inductance. To ensure the compressive strength of the device, the two electrodes are respectively arranged on the cast resin body and fixed there by casting.

For a high-voltage rectangular contact brush used to establish a conductive connection with the static contact in the sleeve-type through-hole, the rectangular sleeve-type through-hole gradually increases from the inside to the outside in a step-like manner, and the enlarged The electrical resistance in the region of the air gap and the cast resin wall is reduced so that the electric field strength in the region of this measuring voltage (Bemessungsspannung) no longer has a destructive effect.

These measures are also supported by the interaction of a U-shaped external control electrode at ground potential, by means of which the electric field strength of the voltage-carrying static contact is reduced by the equipotential lines formed relative to the external control electrode. Due to the direct arrangement of the external electrodes in the area of the front strip, the negative effects of the voltage breakdowns that usually occur at the sharp-edged strips and the partial discharges inside the sleeve-shaped through-holes are largely excluded.

The disk-shaped internal control electrode influences the electric field and the equipotential lines of the cast resin in such a way that the static contact has a correspondingly increased effect due to a markedly reduced air gap to the sleeve-shaped through-opening. The disc-shaped internal control electrode makes the electric force lines of the static contact form a practical spherical distribution.

A preferred embodiment of the present invention is realized by following further technical characterictic:

2.1 One side of the external control electrode is conductively connected to a ground potential terminal,

2.2 The ground potential terminal is arranged on the front side of the support plate area.

In this preferred form, the ground potential terminal can thus be accessed from the outside without additional installation effort.

Another preferred embodiment of the present invention comprises following further technical feature:

3.1 The wiring part contains a current transformer core,

3.2 The current transformer core concentrically surrounds the primary conductor,

3.3 The primary conductor forms such a conductive connection with the conductor terminal that at least a part of the current transformer core area is shielded outwards at a distance from the primary conductor.

With this configuration of the primary conductors, the compressive strength is increased by the corresponding bundling of the equipotential lines in the current transformer core.

Yet another preferred embodiment of the present invention obtains by following further technical feature:

4.1 The sleeve type current transformer is an annular core transformer,

4.2 The primary wire is extended so that the entire current transformer core is shielded outward. For toroidal core transformers, this increases the compressive strength.

Description of drawings

The present invention will be described in detail through two embodiments described by the accompanying drawings, wherein Fig. 1 and Fig. 2 describe a sleeve-type current transformer, Fig. 3 and Fig. 4 describe a sleeve-type support insulator, respectively Two engineering views are presented: a cutaway side view and a top view.

Detailed ways

Figure 1 shows an embodiment of a sleeve-type current transformer DSW arranged on a support plate TBL, shown in a partial cutaway view so that the static contact GKT with its primary conductor PLT and conductor connection can be seen Terminal LTA. At the same time it can be seen that the primary conductor PLT cast in the cast resin is surrounded concentrically by the current transformer core SWK of the sleeve current transformer DSW also cast in the cast resin body GHK (Fig. 2) and that in In the connection region to the conductor terminal LTA at least a part of the current transformer core SWK is surrounded above and approximately at the same distance from the primary conductor PLT running back. In particular, in the lower partial sectional view of the sleeve-type current transformer DSW it can be seen that in the region of the sleeve-type through-opening DFO the same step-like structure is used to increase the distance of the leakage current. Indicated by the schematically depicted front strip FBP, the sleeve-type current transformer DSW in a medium-voltage switchgear can be positioned on its front side via a slot not given a reference number. In this case, the primary conductor PLT is electrically conductively connected to the conductor terminal LTA in such a way that at least a part of the current transformer core SWK is shielded to the outside at a distance from the primary conductor. In addition, the sleeve-type current transformer DSW is a ring core transformer; and the primary wire PLT is lengthened so that the entire current transformer core SWK is shielded outward.

Furthermore, an external control electrode SEA is arranged in the front strip area FBP, one side of which is connected to a defined ground potential via the ground potential connection EPA. As already described above, the electric field strength originating from the live static contact GKT in the sleeve-type through-opening DFO can thus be reduced by correspondingly controlling the equipotential lines formed by the external control electrode. Partial discharges and voltage breakdowns are thereby avoided, especially at sharp edges of the front strips.

FIG. 2 shows a plan view of the sleeve-type current transformer, from which it can be seen in particular that the cast resin body GHK is fixed inside the medium-voltage switchgear front strip FBP. In particular, the arrangement of the support arm STA and the preferably circular cross-sectional shape of the terminal part AFT with the externally accessible conductor terminals LTA can also be seen in this figure.

From Fig. 3 there can be seen an embodiment of a sleeve-type standoff insulator DFS with a cast resin body GHK whose main function is only to provide a pluggable connected electrical connection. For this purpose, a contact arm with high potential has to be arranged reliably and without voltage breakdown at the same position as in the sleeve current transformer, however the fixed contact, not shown, can be connected to the sleeve current transformer. end of hole DFO. The sleeve-type support insulator DFS likewise has a support arm STA for absorbing the load forces of devices, not shown, connected to the conductor connections LTA. The sleeve-type support insulator DFS is likewise detachably connected to the carrier plate TBL.

In particular, the preferably circular cross-sectional shape of the terminal part AFT as well as the conductor terminal LTA and the support arm STA, which is here configured as a bracket, can be seen from the plan view of FIG. 4 described below.

Claims (8)

1. telescopic standoff that is used for the air insulation medium voltage switchgear equipment sealed by metal shell, it is arranged on the support plate, and removably is connected with this support plate, it is characterized in that:

Described telescopic standoff (DFS) has a rectangular sleeve cartridge type through hole (DFO) that outwards becomes step-like mistake to go out in the front side,

Connecting a connecting part layout perpendicular with it, that have the circular cross section profile (AFT) on this telescopic through hole (DFO), side has the lead wire terminal (LTA) of outwards drawing thereon;

This lead wire terminal (LTA) is connected with a fixed contact (GKT) conduction through a lead (PLT);

This telescopic through hole (DFO) and connecting part (AFT) are the parts of same casting resin body (GHK);

This casting resin body (GHK) has the external control electrode (SEA) of the U-loop of a casting in casting resin around this through hole in the zone, front side of this telescopic through hole (DFO);

This casting resin body is provided with casting dish type internal control electrode (SEI) in casting resin, will this telescopic through hole (DFO) shielding in the junctional area of this telescopic through hole (DFO) and connecting part (AFT).

2. according to the described telescopic standoff of claim 1, it is characterized in that:

Described external control electrode (SEA) side can be conducted electricity with earth potential terminals (EPA) and is connected;

These earth potential terminals (EPA) are arranged on a side of the close external control electrode (SEA) in support plate (TBL) district.

3. according to claim 1 or 2 described telescopic standoffs, it is characterized in that:

Described connecting part (AFT) comprises a current transformer core (SWK);

This current transformer core (SWK) is surrounded this lead (PLT) with one heart;

This lead (PLT) is to be connected with described lead wire terminal (LTA) one-tenth conduction like this,, makes that the part zone of this current transformer core (SWK) is equally spaced surrounded also thus to outside conductively-closed by a lead (PLT) at least that is.

4. according to the described telescopic standoff of claim 3, it is characterized in that:

Described bushing type current transformer (DSW) is the ring-shaped core instrument transformer;

A described lead (PLT) is lengthened to and makes whole current transformer core (SWK) to outside conductively-closed.

5. bushing type current transformer that is used for the air insulation medium voltage switchgear equipment sealed by metal shell, it is arranged on the support plate, and removably is connected with this support plate, it is characterized in that:

Described bushing type current transformer (DSW) has a rectangular sleeve cartridge type through hole (DFO) that outwards becomes step-like mistake to go out in the front side,

Connecting a connecting part layout perpendicular with it, that have the circular cross section profile (AFT) on this telescopic through hole (DFO), side has the lead wire terminal (LTA) of outwards drawing thereon;

This lead wire terminal (LTA) is connected with a fixed contact (GKT) conduction through a lead (PLT);

This telescopic through hole (DFO) and connecting part (AFT) are the parts of same casting resin body (GHK);

This casting resin body (GHK) has the external control electrode (SEA) of the U-loop of a casting in casting resin around this through hole in the zone, front side of this telescopic through hole (DFO);

This casting resin body is provided with casting dish type internal control electrode (SEI) in casting resin, will this telescopic through hole (DFO) shielding in the junctional area of this telescopic through hole (DFO) and connecting part (AFT).

6. according to the described bushing type current transformer of claim 5, it is characterized in that:

Described external control electrode (SEA) side can be conducted electricity with earth potential terminals (EPA) and is connected;

These earth potential terminals (EPA) are arranged on a side of the close external control electrode (SEA) in support plate (TBL) district.

7. according to claim 5 or 6 described bushing type current transformers, it is characterized in that:

Described connecting part (AFT) comprises a current transformer core (SWK);

This current transformer core (SWK) is surrounded this lead (PLT) with one heart;

This lead (PLT) is to be connected with described lead wire terminal (LTA) one-tenth conduction like this,, makes that the part zone of this current transformer core (SWK) is equally spaced surrounded also thus to outside conductively-closed by a lead (PLT) at least that is.

8. according to the described bushing type current transformer of claim 7, it is characterized in that:

Described bushing type current transformer (DSW) is the ring-shaped core instrument transformer;

A described lead (PLT) is lengthened to and makes whole current transformer core (SWK) to outside conductively-closed.