FIELD

The present invention relates to an electric current switching apparatus. BACKGROUND

5 In a switch, having a roll-shaped actuator, the moving contacts are often placed such that they go through the actuator. When the moving contact is opened from a stationary contact, the shortest opening gap, defining a propagation path for an arc may go along the surface of the actuator.

To address this problem, the body of the switch pole may be length- i o ened such that an arc is formed away from the actuator to avoid erosive effects thereon. One way to implement this is to lengthen the movable contact, and use a knife-like elongate form. Additionally, the stationary contact may be placed such that it resides within the switch as little as possible.

However, mounting of cables to the stationary contact causes stress 15 thereon and may damage the stationary contact deteriorating the switching performance.

SUMMARY

An object of the present invention is to provide a switch so as to alleviate the above disadvantages. The object of the invention is achieved with a switch, 20 which is defined in the independent claim. Some embodiments are disclosed in the dependent claims.

The invention relates to an electric switch for switching electric current. The application areas of the switch include electric motors and solar systems, for instance.

25 In the switch according to the invention there is provided a stationary contact and a movable contact to be contacted with the stationary contact. The stationary contact comprises a contact portion for contacting to the movable contact, and a mounting portion for supporting the stationary contact to the switch module housing. The mounting portion is placed closer to the centre of the switch

30 module than the contact portion. There may be provided protection and support for the mounting portion. The support may be provided by having one or more wall sections in the switch. In an embodiment, the support/protection is provided by having a receptacle for receiving the mounting portion of the stationary contact.

This arrangement implies that no compromises need to be done in view of achieving a long opening distance between the contacts. The stationary contact is formed accordingly such that the contact portion lies between the mounting portion and a connection portion used for connecting the stationary contact externally.

DRAWINGS

In the following, the invention will be described in greater detail by means of some embodiments with reference to the accompanying drawings, in which

Figure 1 shows a view of an embodiment of a switch module; Figure 2 shows another view of an embodiment of a switch module; Figure 3 shows an embodiment of a switch module seen from the top;

Figures 4A to 4C show an embodiment of a stationary contact from three different viewing angles.

DETAILED DESCRIPTION

The embodiments relate to a switch usable in switching a direct current. Application areas include electric motors and solar panel assemblies, for instance.

To maximize the switching efficiency, a switch having one or more poles may be provided. Each pole comprises stationary contact(s) and a rotary contact connectable with the stationary contact(s). The poles may be connected with cables or shorting members which connect the stationary contacts of the neighbouring poles together.

Figure 1 shows some of the elements of a pole/module of the switch. The pole has a bottom module housing 100, and a top module housing 102, which are mountable together to form one pole of the switch. There is provided a contact area 104, where the rotary contact and the stationary contact are contacted and separated from each other. The stationary contact 1 10 is shown in Figure 1 before mounting to the bottom housing 100. The bottom housing 100 comprises a receptacle 1 14 for receiving a mounting portion 1 10A of the stationary contact. The receptacle provides support for and protects the stationary contact from one or more directions. Firstly, the receptacle includes a bottom wall, against which the stationary contact is placed. Furthermore, the receptacle may provide support for the stationary contact from one or more directions, such as from left, end and right.

Figure 1 also shows a support element 1 16 of the top housing, which supports the stationary contact from top when the housings are assembled to- gether and the stationary contact is placed into the receptacle. In an embodiment, the dimensions of the support element 1 16 are such that it also fits into receptacle and fills the part of the receptacle 1 14, which is not filled by the mounting portion 1 10A of the stationary contact 1 10. Thereby when the top and bottom housings are assembled together, the stationary contact is pressed and supported tightly in the receptacle.

Figure 2 shows a situation where the stationary contact is placed into the receptacle of the bottom housing.

It can be seen that a great part, that is, a connection portion 1 10C, of the stationary contact resides outside of the switch bottom housing 100. The con- nection portion comprises a hole 1 1 0D for receiving a bolt and nut used in fastening of a cable to the connection portion of the stationary contact. As the connection portion 1 10C and the hole 1 10D are placed relatively far outside of the housing 100, a strong torque is produced to the stationary contact 1 10 when the cable is attached to the connection portion 1 10C of the stationary contact.

The stationary contact 1 10 also comprises a contact portion 1 10B, which is placed as close as possible to the end of the housing, where the stationary contact exits the housing, to achieve as long opening distances between the contacts as possible. Thereby an arc caused by separating the contacts is induced far away from an actuator of the switch such that it is avoided that the arc propa- gates along the actuator.

Figure 2 also shows the mounting portion 1 10A of the stationary contact 1 10. The mounting portion has been placed into the receptacle 1 14 which is adapted to receive the mounting portion with tight fitting. In one embodiment, the mounting portion 1 10A has substantially a rectangular shape.

It can be seen from Figure 2 that the mounting portion 1 10A fills the receptacle only in part such that the rest of the receptacle can be filled by the sup- port portion of the top cover of the pole housing. When the housing modules are assembled together, the mounting portion becomes fully covered and surrounded by insulating material provided by the receptacle 1 14 and the support portion of the second housing module. Thereby there is no risk of that the arc would propagate towards the mounting portion 1 10A.

Figure 2 also shows a housing for an actuator 1 18 or rotary contact to be contacted by the contact portion 1 10B of the stationary contact. It can be seen that the mounting portion 1 10A is tilted to an angle with respect to the contact portion 1 10B and/or the connection portion 1 10C. The effect with the tilting is that the mounting portion 1 1 OA can be placed aside from and next to the housing for the rotary contact 1 18. The connection portion 1 10C and/or the contact portion 1 10B may point substantially towards the rotary contact housing 1 18.

It can be seen, that the stationary contact 1 10 is constructed such that the connection portion 1 10B lies between the mounting portion 1 10A and the contact portion 1 10C. In this way the contact portion 1 10B can be placed close to the edge of the housing where the stationary contact exits the housing to maximize the opening distance formed between the contacts.

The receptacle for the mounting portion protects the mounting portion 1 1 OA from bending during the mounting of the cable contacts to the connection portion 1 10C. Furthermore, the receptacle provides support for the contact portion 1 10B such that the contact portion is kept tightly it its place during connecting and disconnecting of the contacts thereby providing security for the success of the switching event.

Figure 3 shows an embodiment of a pole bottom housing 1 00 equipped with parts of the switch module.

In Figure 3, the actuator housing is equipped with an actuator 120, which has the rotary contact attached thereto. The rotary contacts are knife-like elongate blades, which pass through the actuator towards both ends of the pole. The stationary contact's contact portion 1 10B is to be contacted by the rotary contact 122 blades. The blades may have a sandwich structure having two blades, where between the contact portion 1 1 OB is placed when the contact is made at the contact area 104. The switch of Figure 3 is shown in fully open posi- tion when the contact blade 122 is relatively far away from the contact portion 1 10B.

It can be seen that the mounting portion 1 10A is positioned closer to the centre of the switch module 100 than the contact portion 1 10B. The contact portion 1 10B may be placed substantially in the half-way between the outer edge of the actuator 120 and the edge of the switch module. The centre of the switch module may coincide with the rotation axis of the movable/rotary contact actuator 120. As the mounting portion is closer to the module centre than the contact portion 1 10B, the stationary contact can efficiently be protected from detrimental effects when the stationary contact's connection portion 1 10C is connected to external cables. That is, the mounting portion is located far away from the connection portion 1 10C and an exit slot of the stationary contact from the housing, and provides thereby a great torque against bending of the stationary contact.

There may be provided protection for the mounting portion 1 10B against an arc building up when the rotary contact blades 1 22 are separated from the contact portion 1 10B of the stationary contact. The protection provides protection also in a situation when electrically conductive carbon black is formed to the surface of the actuator. In such a situation an arc might try to burn on the surface of the actuator via the mounting portion. The protection of the mounting portion may be provided by having one or more insulating wall sections around the mount- ing portion. Preferably, one such wall section is arranged substantially between the mounting portion and the arc chamber housing the quenching plates 124.

As the figure shows, the contact area 104, and correspondingly a disconnection area having the quenching plates 124 is located at a distance from the actuator 120. Thereby it is avoided that the actuator surface forms a contact bridge for the arc. The disadvantage in moving the contact area far away from the actuator is that the contact portion 1 10B practically resides fairly close to the edge of the switch housing. Fastening of external contacts to the connection portion 1 10C may cause twisting of the stationary contact 1 10. The embodiment of Figure 3 meets this problem by providing a receptacle 1 14 for receiving a mounting portion 1 10A of the stationary contact. The stationary contact is supported at least from two points, by the receptacle 1 14, and an exit hole in the housing 100 at the point where the stationary contact exits the housing. The mounting portion 1 10A is housed by the receptacle from the bottom and three sides, and a support portion of the top cover may fill the rest of the receptacle. Thus, the mounting portion is fully covered, and as the receptacle and the support portion are made of electrically insulating material, the mounting portion is electrically insulated and there is no risk that the mounting portion 1 1 OA would function as a contact bridge.

Figure 3 shows also a stoppage element 126 of the actuator 120. It can be seen that the actuator has a round cylindrical base portion, and one or more stoppage elements are arranged as wings projecting from the cylindrical base portion. The side of the stoppage element, which faces the opening direction, may project substantially perpendicularly from the cylindrical base portion. In Figure 3, there are two stoppage elements 126 on opposite sides of the cylindrical base portion of the actuator.

The stoppage element may be a molded and integral part of the actuator. When the contact is opened, springs or other force-transmitting elements may be used such that the contact is opened as rapidly as possible. The rapid opening of the switch sets high requirements to stopping of the opening rotation of the actuator. In the embodiment of Figure 3, the receptacle is arranged such that is works as a stoppage support for the stoppage element 126 of the actuator. It can be seen that when the actuator is its open position, the stoppage element has a wall section which sets against a parallel wall section of the receptacle.

Figure 3 shows a through hole housing 128 for receiving a bolt which connects and fastens the bottom housing and top housing of one or more poles together. As can be seen, the through hole housing is positioned behind the receptacle such as to further provide support for the receptacle against forces caused by the stoppage element 126 due to the opening of the contacts.

As can be seen, the stationary contact is tilted from a point inside the housing 100 that is close to the edge of the housing. The stationary contact has an elongate base structure, which is arranged to an angle with respect to the connec- tion portion 1 10C. Thereby the total length of the stationary contact within the module can be maximized thereby maximizing the support provided by the receptacle.

The contact portion 1 10B is arranged between the connection portion 1 10C and the mounting portion 1 1 OA. The contact portion may be arranged as a projection projecting substantially perpendicularly from the base structure of the stationary contact. The contact portion may comprise a base portion projecting from the base of the stationary contact, and a wing-like section arranged to an angle from the base portion of the contact portion.

In the embodiment of Figure 3, the stationary contact thus has in elongate direction two portions, the connection portion 1 10C and the base portion tilted from the connection portion. The mounting portion 1 1 OA and the contact portion are arranged onto the same elongate base portion structure. The mounting portion can be seen as an extension of the stationary contact towards the interior of the switch module.

Figures 4A to 4C show an embodiment of the stationary contact 1 10 seen from different directions.

Figure 4A highlights the elongate structure of the stationary contact 1 10. As can be seen, the contact portion lies between the mounting portion 1 1 OA and the connection portion 1 10C in the longitudinal direction of the contact 1 10. The contact portion comprises a base portion 100BA, which connects the contact portion to the elongate body of the stationary contact. The base portion may be arranged as a projection substantially perpendicularly with respect to the body of the stationary contact, and the mounting portion is arranged as an extension of the stationary contact from the point where the contact portion projects from the stationary contact. The contact portion may also include an actuating portion 100BB, which practically actuates the contact with the rotary contact.

Figure 4B highlights examples of different angles in the stationary contact. By way of an example, the angle between the connection portion 1 10C and the rest of the base body of the stationary contact may be about 1 5 degrees, for instance. In other embodiments, the angle may reside between 5 to 45 degrees, for instance. In the contact portion, the angle between the base portion 1 10BA and the actuating portion 1 10BB may be about 45 degrees, for instance. Figure 4B also shows that the length of the connection portion 1 10C, most of which lies outside of the housing when mounted, is approximately half of the total body length of the stationary contact 1 10.

Figure 4C shows the stationary contact from behind, where it can be seen that the mounting portion 100A sets a little lower than the connection portion 1 10C.lt will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.