The invention relates to fixation assembly for a contact element in gas or air insulated switchgear for medium- or high-voltage use, which is electrically connecting the contact element to a main current path, and mechanically connecting to a frame or support via an isolator element, and a gas or air insulated switchgear for medium- or high-voltage use, according to preamble of claim 1 .

Fixed contacts are usually screwed together with the current leading copper bar. To keep the fixed contact in position an isolator, made of duroplast, thermoplast or eq., is used. To connect the isolator, screw connections are standard. To realize such screw connections, a dowel is necessary and must be realized as insert in the isolator or the contact will be casted into the isolator directly. On opposite side the isolator can be fixed by screw with dowel as well or welded in. For both, the dowels must be designed for field control.

Disadvantages of such well known constructions are, that in order to screw the fixed contact onto a copper bar, time is needed for assembling and handling. In order to lock the screw, a screw locking has to be used. The current will be manly transferred in a circular ring area around the screw. The rest of the surface is not a 100% contact surface.

If the contact is casted into the isolator directly, the contact needs a complex and expensive field control. So it is the object of the invention, to reduce the needed handling time in assembling of the aforesaid parts, but to fulfill high performance in fixation of the aforesaid parts.

The basical feature combination of the invention, in order to overcome the aforesaid problems is, that the isolator element is provided at the contact element side with a cup-shaped entry pilot, and that the contact element is provided with an opening as complementary counterpart for mechanical reception of the entry pilot from its open side of the cup-shaped section, and that a locking plug, insertable from the open side into the entry pilot, secures the mechanical fixation of the of the contact element on the isolator element.

The invention discribes a thermoplastic isolator, which has a snap in feature on contact side to fix the contact onto the isolator. For not losing this connection a locking plug is inserted which realize the form fit. Together with this feature a press fit connection between the contact and a copper bar can be realized, which leads to a propper connection. A bigger contact surface is the result which leads to lower electrical resistance and therefore lower losses.

On the opposite side, the thermoplastic isolator has a mushroom head which makes a slide in assembling without additional fixing possible.

On the same side the thermoplastic isolator has a positioning feature which make an automatic or semi-automatic assembly possible.

In an advantageous embodiment, the cup-shaped entry pilot is slitted in parallel to the inserting direction. By that, the entry pilot can be inserted easy by the so resulted axial spring functionality.

In a further advantageous embodiment, the cup-shaped entry pilot is provided at its open end with a prominent snaping collar, which corresponds with a circular edge in the opening of the contact element, in order to be fixed mechanically by a plug-in and snap-function.

An example for a locking plug can be a disc-shaped locking plug.

An alternative advantageous embodiment is, that the locking plug is cup- shaped, with a collar formed at its closed end, and inserted into the entry pilot of the isolator with its open end.

In a further advantageous embodiment, the isolator element is provided at its opposite end with a further entry pilot which is mushroom headed, referring to an opening in the aforesaid frame or support. This end of the isolator is fixed to the frame or support.

According to that, it is advantageous, that the aforesaid mushroom headed entry pilot is dimensioned in that, a complementary v-formed slide-in-opening in the frame or support interacts with the mushroom headed entry pilot in a slide in direction in such, that the isolator is fixed by a resulting axial fixation force in the end position of the isolator on the frame or support. By that the isolator can be fixed to the frame or support in an mechnically effective way, into a secure end positon.

In a further advantageous embodiment, the contact element itself is cup- shaped. The open end is the electrical contact interface.

By that, the further electrical contacting can easily be realized by a press fit connection.

In a further advantageous embodiment, the isolator is made of thermoplastic material. This results in very good electrical insulation. Furthermore, it can absorb high bending forces during installation and/or maintanence of the switchgear. For the location of the fixation of the contact element, two alternative

embodiments are proposed.

The first advantageous embodiment is formed in such, that the complementary opening, in which the entry pilot of the isolator is or has to be inserted, is placed in the center of the bottom of the cup-shaped contact element.

So the complete installation becomes compact.

A second advantageous embodiment is, that the complementary opening is placed beside the cup-shaped contact element, in a busbar segment, which is electrically and mechanically connected with the contact element.

The fixation assembly can be used profitable in gas or air insulated switchgear, with two or three position switches for medium or high voltage use, with a fixation assembly according to one of the aforesaid claims, installed in the busbar system of the switchgear,

An embodiment of the invention is shown in the drawings:

Figure 1 side view on the principle construction of the fixation assembly

Figure 2 assembly description Figure 3 assembled state Figure 4 alternative

Figure 1 shows in a side view all important elements of the fixation assembly. A contact element 1 is mechanically connected to an isolator 3, preferably made of thermoplastic material. All kind of thermoplastic material can be used. The contact element 1 is cup-shaped and is provided in the bottom with an opening 5. The isolating element 3 is provided at that end, which is mechanically connected to the contact element 1 , with a pilot entry 4, which is formed preferably as one piece segment at the isolator 3.

So the pilot entry 4 of the isolator 3 is inserted into the opening 5 of the contact element 1 .

It can be seen, that at the open end of the pilot entry is formed a prominent collar 4', which results in a plug-in and snap-in function at the end position.

For that, the opening 5 of the contact element is provided with an edge, in which the prominent collar 4' snaps into, in the end position.

The end position is additionally secured by a locking plug 7, inserted into the cup-shaped entry pilot 4 of the isolator 3.

At the opposite end of the isolator 3 is formed a further entry pilot, which coacts complementarily with a v-formed slot in the frame or support 2, in order to fix the isolator 3 with the contact element 1 on the frame por support 2.

Therefore this second entry pilot 6 is formed as mushroom head.

Figure 2 shows partly a perspective view of a not finally assembled state.

It is shown, that the isolator has to be inserted with the axial I y slitted entry pilot 4 into the opening of the contact element 1 . After final insert into end position, a cup shaped locking plug 7 is inserted into the entry pilot 4 of the isolator. The contact element itself is electrically and mechanically connected to a conductor. The opposite end of the isolator is provided with a further entry pilot 6, which is mushroom headed. The mushroom headed entry pilot 6 is provided to realize the mechanical fixation of the contact element 1 on a frame or support.

Figure 3 makes this structural and functional feature visible. The prepared contact element - conductor - isolator part can be fixed on a frame or support by a V-shaped or V-formed slit 9 in the frame or support in the embodied shown slide-in-direction. So the contact element 1 with the connected conductor are mechanically connected to the frame or support of the switchgear but isolated against earth potential of the frame. Figure 4 displays an embodiment, in which the opening 5 for the mechanical reception of the pilot entry 4 of the isolator 3, is not centered in the open end of the contact element 1 , but excentrically, that means directly beneath that.

Any further details of the Isolator - contact element- coupling are realized in the same way.

List of reference signs

1 contact element

2 frame/support

3 isolator

4 entry pilot, cup-shaphed, optionally slitted 4' prominent collar

5 opening

6 mushroom headed further pilot entry

7 locking plug

8 Teeoff conductor

9 V-formed slit in frame/support