Patent Description:
There are two types of electrical switches provided with a neutral pole. In an electrical switch with a simultaneous break mechanism, a neutral pole is adapted to disconnect simultaneously with phase poles during an opening event. In an electrical switch with a late-break mechanism, a neutral pole is adapted to disconnect later than phase poles during an opening event.

It is known in the art to manufacture an electrical switch with a simultaneous break mechanism and an electrical switch with a late-break mechanism such that they both are based on the same phase pole unit, and the type of the electrical switch depends on a type of a neutral pole unit connected to the phase pole unit. The electrical switch with the simultaneous break mechanism is provided by combining the phase pole unit with a neutral pole unit of a simultaneous break type, and the electrical switch with the late-break mechanism is provided by combining the phase pole unit with a neutral pole unit of a late-break type.

One of the disadvantages associated with the above known electrical switches is that it is necessary to manufacture and to keep in stock two different types of neutral pole units.

An example of a known three-phase electrical switch is described in <CIT>.

An object of the present invention is to provide an electrical switch so as to alleviate the above disadvantage. The objects of the invention are achieved by an electrical switch which is characterized by what is stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on the idea of providing an electrical switch with a neutral contact adjustment system having a first operating state adapted to provide a simultaneous break operation, and a second operating state adapted to provide a late-break operation.

An advantage of the electrical switch of the invention is that one and the same electrical switch can be adjusted to operate as a simultaneous break switch or a late-break switch without adding or removing any components from the electrical switch.

In an embodiment, the type of the electrical switch can be changed between simultaneous break and late-break by rotating an operating head with a tool such as a screwdriver.

<FIG> shows an electrical switch, and <FIG> shows an exploded view thereof. The electrical switch comprises a frame <NUM>, an operating mechanism, a bridge assembly <NUM>, a movable contact system, a stationary contact system, a neutral contact adjustment system <NUM>, and a return spring system <NUM>.

The frame <NUM> comprises a first frame portion <NUM>, and a second frame portion <NUM>. A mechanism of the electrical switch is mounted in the frame <NUM>.

The movable contact system has four movable contacts comprising a movable neutral contact <NUM>, and three movable phase contacts <NUM>. The movable contacts are electrically insulated from each other. Each of the movable contacts is movable relative to the frame <NUM> between a connected position and a disconnected position such that the connected position corresponds to a connected state of the electrical switch, and the disconnected position corresponds to a disconnected state of the electrical switch.

The stationary contact system has a stationary phase contact pair for each of the movable phase contacts <NUM>, and a stationary neutral contact pair for the movable neutral contact <NUM>. Each stationary phase contact pair and the stationary neutral contact pair comprises a first stationary contact <NUM> and a second stationary contact <NUM>. The stationary contact system is stationary mounted relative to the frame <NUM>.

In the connected state of the electrical switch, each stationary phase contact pair is electrically conductively connected by a corresponding movable phase contact <NUM>, and the stationary neutral contact pair is electrically conductively connected by the movable neutral contact <NUM>. In the disconnected state of the electrical switch, each stationary phase contact pair is electrically isolated, and the stationary neutral contact pair is electrically isolated.

The bridge assembly <NUM> comprises a bridge body <NUM>, a neutral contact opening surface <NUM>, and a phase contact opening surface <NUM> for each of the movable phase contacts <NUM>. The bridge assembly <NUM> is movable in a depth direction relative to the frame <NUM> between a first bridge position and a second bridge position by means of the operating mechanism. In the connected state of the electrical switch, the bridge assembly <NUM> is in the first bridge position, and in the disconnected state of the electrical switch, the bridge assembly <NUM> is in the second bridge position.

During an opening event, in which the electrical switch transfers from the connected state to the disconnected state, the bridge assembly <NUM> moves from the first bridge position to the second bridge position, the neutral contact opening surface <NUM> is in contact with the movable neutral contact <NUM> for moving the movable neutral contact <NUM> from the connected position to the disconnected position, and each phase contact opening surface <NUM> is in contact with a corresponding movable phase contact <NUM> for moving the movable phase contact <NUM> from the connected position to the disconnected position.

The operating mechanism has a first operating position and a second operating position such that moving of the operating mechanism from the first operating position to the second operating position is adapted to provide the opening event. The operating mechanism comprises an operating shaft <NUM> rotatable relative to the frame <NUM> such that a first shaft position of the operating shaft <NUM> corresponds to the first operating position of the operating mechanism, and a second shaft position of the operating shaft <NUM> corresponds to the second operating position of the operating mechanism. A rotation axis of the operating shaft <NUM> is parallel with the depth direction. The operating shaft <NUM> is adapted to remain stationary in the depth direction during a rotation between the first shaft position and the second shaft position.

During the opening event, the operating shaft <NUM> is adapted to exert a first opening force to the bridge assembly <NUM> for moving the bridge assembly <NUM> from the first bridge position to the second bridge position. The operating shaft <NUM> comprises a first screw thread surface <NUM>, and the bridge body <NUM> comprises a second screw thread surface adapted to co-operate with the first screw thread surface <NUM> during the opening event such that said co-operation provides the first opening force.

The bridge body <NUM> is made of electrically insulating material. The phase contact opening surfaces <NUM> are stationary relative to the bridge body <NUM>. The phase contact opening surfaces <NUM> are integral parts of the bridge body <NUM>.

The neutral contact adjustment system <NUM> is adapted for adjusting a position of the neutral contact opening surface <NUM> relative to the phase contact opening surfaces <NUM>. Therefore, the neutral contact adjustment system <NUM> is also adapted for adjusting a position of the neutral contact opening surface <NUM> relative to the bridge body <NUM>.

The neutral contact adjustment system <NUM> has a first operating state and a second operating state. The first operating state is adapted to provide a simultaneous break operation in which the movable neutral contact <NUM> disconnects simultaneously with the movable phase contacts <NUM> during the opening event. The second operating state is adapted to provide a late-break operation in which the movable neutral contact <NUM> disconnects later than the movable phase contacts <NUM> during the opening event.

<FIG> show a portion of the mechanism of the electrical switch shown in <FIG> from different directions, in a situation where the neutral contact adjustment system <NUM> is in the first operating state. <FIG> shows the portion of the mechanism shown in <FIG> in cross section. <FIG> show the portion of the mechanism of the electrical switch shown in <FIG> from different directions, in a situation where the neutral contact adjustment system <NUM> is in the second operating state. <FIG> shows the portion of the mechanism shown in <FIG> in cross section. <FIG> shows an enlargement of the neutral contact adjustment system <NUM>.

The neutral contact adjustment system <NUM> comprises a first adjustment member <NUM>, a second adjustment member <NUM>, and a retaining spring <NUM>. The first adjustment member <NUM> and the second adjustment member <NUM> are made of electrically insulating material. The retaining spring <NUM> is a coil spring.

The first adjustment member <NUM> is rotatable relative to the bridge body <NUM> between a simultaneous break position and a late-break position. An angle between the simultaneous break position and the late-break position is <NUM>°. The second adjustment member <NUM> comprises the neutral contact opening surface <NUM>, and is movable in the depth direction relative to the bridge body <NUM> between a simultaneous break location and a late-break location by rotation of the first adjustment member <NUM> between the simultaneous break position and the late-break position. The neutral contact opening surface <NUM> is an integral part of the second adjustment member <NUM>.

The first adjustment member <NUM> is an eccentric member comprising a first contact surface <NUM> and a second contact surface <NUM> such that a distance between a rotation axis of the first adjustment member <NUM> and the first contact surface <NUM> is greater than a distance between the rotation axis of the first adjustment member <NUM> and the second contact surface <NUM>. The rotation axis of the first adjustment member <NUM> is stationary relative to the bridge body <NUM> such that the first adjustment member <NUM> is only adapted to rotate relative to the bridge body <NUM>.

The second adjustment member <NUM> comprises a counter surface <NUM> such that in the simultaneous break position of the first adjustment member the counter surface <NUM> is in contact with the first contact surface <NUM>, and in the late-break position of the first adjustment member the counter surface <NUM> is in contact with the second contact surface <NUM>. The counter surface <NUM> is an integral part of the second adjustment member <NUM>.

The first contact surface <NUM> and the second contact surface <NUM> are shaped as recesses, and the counter surface <NUM> is shaped as a protrusion. As best seen in <FIG>, <FIG> and <FIG>, the first adjustment member <NUM> comprises two first contact surfaces <NUM>, and two second contact surfaces <NUM> such that a cross-section of the first adjustment member <NUM> on a plane perpendicular to the rotation axis thereof resembles slightly a butterfly or a four-leaved clover.

The retaining spring <NUM> exerts a first spring force to the bridge body <NUM> and a second spring force to the second adjustment member <NUM>. The second spring force is pressing the second adjustment member <NUM> against the first adjustment member <NUM> in order to resist movement of the first adjustment member <NUM> between the simultaneous break position and the late-break position.

The first adjustment member <NUM> and the second adjustment member <NUM> are shaped such that the first adjustment member <NUM> has an intermediate position between the simultaneous break position and the late-break position such that in the intermediate position of the first adjustment member <NUM>, the retaining spring <NUM> presses the second adjustment member <NUM> stronger against the first adjustment member <NUM> than in the simultaneous break position and in the late-break position. Therefore, the shapes of the first adjustment member <NUM> and the second adjustment member <NUM> are adapted to resist movement of the first adjustment member <NUM> between the simultaneous break position and the late-break position such that the first adjustment member <NUM> is not able to rotate from the simultaneous break position to the late-break position or from the late-break position to the simultaneous break position without an external force applied to the first adjustment member <NUM>.

The first adjustment member <NUM> comprises an operating head <NUM> adapted for rotating the first adjustment member <NUM> between the simultaneous break position and the late-break position. The operating head <NUM> is adapted to be rotated with a screwdriver.

<FIG> shows a side view of the electrical switch in the connected state, and <FIG> shows a side view of the electrical switch in the disconnected state. In <FIG>, the depth direction is a horizontal direction. <FIG> show that the frame <NUM> is provided with an adjustment aperture <NUM> such that in the connected state of the electrical switch, the operating head <NUM> is accessible through the adjustment aperture <NUM>, and in the disconnected state of the electrical switch the frame <NUM> blocks access to the operating head <NUM>. In other words, the operating head <NUM> is accessible in the first bridge position, and inaccessible in the second bridge position.

The first adjustment member <NUM> is adapted to provide a visible position indication indicating whether the first adjustment member <NUM> is in the simultaneous break position or the late-break position. The operating head <NUM> has a slot head adapted to be driven by a flat-bladed screwdriver, and therefore a direction of the slot head indicates whether the first adjustment member <NUM> is in the simultaneous break position or in the late-break position.

The return spring system <NUM> is adapted to exert return forces to the movable contact system in order to return the movable neutral contact <NUM> and the movable phase contacts <NUM> to their connected positions if they are deflected therefrom in the direction of the disconnected positions thereof. The return spring system <NUM> comprises four return springs <NUM>, <NUM>, <NUM> and <NUM>. Each of the return springs <NUM>, <NUM> and <NUM> is in contact with a corresponding movable phase contact <NUM>. The return spring <NUM> is in contact with the movable neutral contact <NUM>.

It should be note that in <FIG>, <FIG>, the return springs <NUM>, <NUM>, <NUM> and <NUM> are depicted in their resting position which means that the return springs are neither compressed nor extended. In a complete, operational electrical switch, the return springs <NUM>, <NUM>, <NUM> and <NUM> are slightly compressed in the connected state of the electrical switch, and more compressed in the disconnected state of the electrical switch. In other words, in a complete, operational electrical switch, the return springs <NUM> - <NUM> are tensioned also in the connected state of the electrical switch thereby pressing the movable contacts against corresponding stationary contacts.

The first stationary contacts <NUM> and the second stationary contacts <NUM> of the electrical switch are located on the same plane. In the connected state of the electrical switch, the movable neutral contact <NUM> and the movable phase contacts <NUM> are in contact with the first stationary contacts <NUM> and the second stationary contacts <NUM> such that there is a small gap between the neutral contact opening surface <NUM> and the movable neutral contact <NUM>, and between each phase contact opening surface <NUM> and a corresponding movable phase contact <NUM>.

In the connected state of the electrical switch, an operating state of the neutral contact adjustment system <NUM> affects a size of a gap between the neutral contact opening surface <NUM> and the movable neutral contact <NUM>. In the second operating state of the neutral contact adjustment system <NUM> said gap is greater than in the first operating state. It is the larger gap that provides the late-break operation.

In the disconnected state of the electrical switch, the neutral contact opening surface <NUM> is in contact with the movable neutral contact <NUM>, and each phase contact opening surface <NUM> is in contact with a corresponding movable phase contact <NUM> regardless of the operating state of the neutral contact adjustment system <NUM>.

Claim 1:
An electrical switch comprising:
a frame (<NUM>);
a movable contact system having a plurality of movable contacts comprising a movable neutral contact (<NUM>), and at least one movable phase contact (<NUM>), each of the movable contacts being movable relative to the frame (<NUM>) between a connected position and a disconnected position;
a bridge assembly (<NUM>) comprising a bridge body (<NUM>), a neutral contact opening surface (<NUM>), and a phase contact opening surface (<NUM>) for each of the at least one movable phase contact (<NUM>), the bridge assembly (<NUM>) being movable in a depth direction relative to the frame (<NUM>) between a first bridge position and a second bridge position,
wherein during an opening event, in which the electrical switch transfers from a connected state to a disconnected state, the bridge assembly (<NUM>) moves from the first bridge position to the second bridge position, the neutral contact opening surface (<NUM>) is in contact with the movable neutral contact (<NUM>) for moving the movable neutral contact (<NUM>) from the connected position to the disconnected position, and each phase contact opening surface (<NUM>) is in contact with a corresponding movable phase contact (<NUM>) for moving the movable phase contact (<NUM>) from the connected position to the disconnected position,
characterized in that the electrical switch comprises a neutral contact adjustment system (<NUM>) adapted for adjusting a position of the neutral contact opening surface (<NUM>) relative to the at least one phase contact opening surface (<NUM>) such that the neutral contact adjustment system (<NUM>) has a first operating state which is adapted to provide a simultaneous break operation in which the movable neutral contact (<NUM>) disconnects simultaneously with the at least one movable phase contact (<NUM>) during the opening event, and a second operating state which is adapted to provide a late-break operation in which the movable neutral contact (<NUM>) disconnects later than the at least one movable phase contact (<NUM>) during the opening event.