EP3594982A1

EP3594982A1 - A three phase earthing switch

Info

Publication number: EP3594982A1
Application number: EP18183234.6A
Authority: EP
Inventors: Josef Cernohous; Pavel Hemek; David Rumler; Emil Kalina
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2018-07-12
Filing date: 2018-07-12
Publication date: 2020-01-15
Also published as: CN211150399U

Abstract

The present invention relates to a three phase earthing switch (50). The earthing switch has at least one base unit (1), three connectors (4), and three earth contacts (12). The at least one base unit is configured to hold the three connectors. A first distil end of each of the three connectors is configured to rotate with respect to the at least one base unit. A second distil end of each of the three connectors comprises a contact knife. The three earth contacts are configured to be mounted at three locations that are mechanically independent from and spaced from the at least one base unit. In a first mode of operation the three connectors are not in contact with the three earth contacts. In a second mode of operation the three connectors are moved such that the three contact knifes are in contact with the three earth contacts.

Description

FIELD OF THE INVENTION

The present invention relates to a three phase earthing switch and to a method for providing a three phase earthing switch.

BACKGROUND OF THE INVENTION

An earthing switch is an important device in a medium voltage switchgear. The role of the earthing switch is to safely interconnect working conductors to earth potential in order that it is safe to operate and/or work closely to these conductors in what can be restricted surroundings. There is however a need to improve performance, reduce cost, and at the same time reduce complexity of earthing switches.

SUMMARY OF THE INVENTION

Therefore, it would be advantageous to have an improved technology for providing a three phase earthing switch.
The object of the present invention is solved with the subject matter of the independent claims, wherein further embodiments are incorporated in the dependent claims. It should be noted that the following described aspects of the invention apply also for the three phase earthing switch and for the method of providing a three phase earthing switch.
In a first aspect, there is provided a three phase earthing switch, comprising:

at least one base unit;
three connectors; and
three earth contacts.

The at least one base unit is configured to hold the three connectors. A first distil end of each of the three connectors is configured to rotate with respect to the at least one base unit. A second distil end of each of the three connectors comprises a contact knife. The three earth contacts are configured to be mounted at three locations that are mechanically independent from and spaced from the at least one base unit. In a first mode of operation of the three phase earthing switch the three connectors are not in contact with the three earth contacts. In a second mode of operation of the three phase earthing switch the three connectors are moved such that the three contact knifes are in contact with the three earth contacts.
In an example, the three locations of the earth contacts are adjustable to vary the spacing from the at least one base unit.
Thus, the fixation points are freely adjustable in their distance from the at least one base unit.
In an example, each of the three earth contacts has a recess configured to receive a contact knife of a connector.
In an example, the at least one base unit is formed from three base units, wherein each connector is held by and configured to rotate with respect to a corresponding base unit. The three connectors are electrically connected to each other, and the three base units are configured to be mounted at three locations spaced from each other.
In an example, at least two of the three base units are configured such that locations of two of the three base units are adjustable to vary the spacing between the three base units.
In an example, a first exchangeable interconnecting bar is configured to electrically connect a first one of the three base units to a second one of the three base units, and a second exchangeable interconnecting bar is configured to electrically connect the second one of the three base units to a third one of the three base units.
Thus, when the spacing between the three base units is varied, the interconnecting bars can be changed to ones of the correct length.
In an example, the three phase earthing switch has an exchangeable shaft that is held by the at least one base unit.
Thus, when the spacing between the three base units is varied, the shaft can be changed to one of the correct length.
In an example, the shaft is fixedly held by the at least one base unit, and wherein the three connectors are configured to rotate with respect to the shaft.
In an example, the shaft is configured to rotate with respect to the at least one base unit, and wherein the three connectors are fixedly connected to the shaft.
In an example, a position indicator associated with the shaft is configured to indicate when the three phase earthing switch is in a position associated with the second mode of operation.
In an example, the earthing switch comprises movement limiting means.
In an example, the movement limiting means comprises at least one movement stopper fixedly attached to the at least one base unit, and comprises at least one movement limiting component fixedly attached to at least one of the three connectors. In a transition from the first mode of operation to the second mode of operation at least a first part of the at least one movement limiting component is moved toward the at least one movement stopper.
In an example, in the second mode of operation the at least first part of the at least one movement limiting component is configured to be in contact with the movement stopper.
In an example, in a transition from the second mode of operation to the first mode of operation at least a second part of the at least one movement limiting component is moved toward the at least one movement stopper.
In an example, in the first mode of operation the at least second part of the at least one movement limiting component is configured to be in contact with the movement stopper.
In an example, the three phase earthing switch comprises at least one spring. Activation of the at least one spring is configured to transition the three phase earthing switch from the first mode of operation to the second mode of operation.
In an example, a first end of the at least one spring is connected to the at least one base unit and configured to rotate with respect to the at least one base unit. When the at least one spring is activated a second end of the at least one spring is configured to interact with at least one of the three connectors to rotate the three connectors.
In a second aspect, there is provided a method of providing a three phase earthing switch, comprising:

a) holding three connectors by at least one base unit, wherein a first distil end each of the three connectors can rotate with respect to the at least one base unit, and wherein a second distil end each of the three connectors comprises a contact knife;
b) mounting three earth contacts at three locations that are mechanically independent from and spaced from the at least one base unit; and

in a first mode of operation the three connectors are not in contact with the three earth contacts; and
in a second mode of operation the three connectors are moved such that the three contact knifes are in contact with the three earth contacts.

The above aspects and examples will become apparent from and be elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will be described in the following with reference to the following drawings:

Fig. 1: shows a schematic representation of an example of a three phase earthing switch;
Fig. 2: shows a method of providing a three phase earthing switch;
Fig. 3: shows a detailed structure of an example of a three phase earthing switch; and
Fig. 4: shows a detailed structure of a part of the example of the three phase earthing switch as shown in Fig. 3;
Fig. 5: shows a detailed structure of a part of the example of the three phase earthing switch as shown in Fig. 3; and
Fig. 6: shows a detailed structure of a part of the example of the three phase earthing switch as shown in Fig. 3.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 shows an example of a three phase earthing switch 50, where optional features are shown in dashed form. The three phase earthing switch comprises at least one base unit 1, three connectors 4, and three earth contacts 12. The at least one base unit is configured to hold the three connectors. A first distil end each of the three connectors can rotate with respect to the at least one base unit. A second distil end each of the three connectors comprises a contact knife. The three earth contacts are mounted at three locations that are mechanically independent from and spaced from the at least one base unit. In a first mode of operation, the three connectors are not in contact with the three earth contacts. In a second mode of operation, the three connectors are moved such that the three contact knifes are in contact with the three earth contacts.
In an example, at least one earthing wire 7 is electrically connected to at least one of the connectors.
In an example, the three earth contacts when mounted at the three locations are not in electrical connection with the at least one base unit. In other words, the earth contacts are fixed on fixation points, which are mechanically and statically independent from the at least one base unit.
According to an example, the three locations of the earth contacts are adjustable to vary the spacing from the at least one base unit.
According to an example, each of the three earth contacts has a recess configured to receive a contact knife of a connector.
According to an example. the at least one base unit is formed from three base units, Each connector is held by and can rotate with respect to a corresponding base unit. The three connectors are electrically connected to each other. The three base units are mounted at three locations spaced from each other.
In an example, each connector is fixedly attached to a moving contact holder 5. Each of the three moving contact holders is configured to rotate with respect to a corresponding base unit.
In an example, each base unit comprises two bent pieces of metal 11.
According to an example, at least two locations of two of the three base units are adjustable to vary the spacing between the three base units.
According to an example, a first exchangeable interconnecting bar 6 electrically connects a first one of the three base units to a second one of the three base units. A second exchangeable interconnecting bar 6 electrically connects the second one of the three base units to a third one of the three base units.
According to an example, the three phase earthing switch comprises an exchangeable shaft 2 that is held by the at least one base unit.
According to an example, the shaft is fixedly held by the at least one base unit, and wherein the three connectors are configured to rotate with respect to the shaft.
According to an example, the shaft is configured to rotate with respect to the at least one base unit, and wherein the three connectors are fixedly connected to the shaft.
According to an example, a position indicator 8 associated with the shaft is configured to indicate when the three phase earthing switch is in a position associated with the second mode of operation.
In an example, the position indicator is configured to indicate when the three phase earth switch is in a position associated with the first mode of operation.
According to an example, the earthing switch comprises movement limiting means 3 and 10.
According to an example, the movement limiting means comprises at least one movement stopper 10 fixedly attached to the at least one base unit, and comprises at least one movement limiting component 3 fixedly attached to at least one of the three connectors. In a transition from the first mode of operation to the second mode of operation at least a first part of the at least one movement limiting component 3 is moved toward the at least one movement stopper 10.
According to an example, in the second mode of operation the at least first part of the at least one movement limiting component 3 is configured to be in contact with the movement stopper 10.
According to an example, in a transition from the second mode of operation to the first mode of operation at least a second part of the at least one movement limiting component 3 is moved toward the at least one movement stopper 10.
According to an example, in the first mode of operation the at least second part of the at least one movement limiting component 3 is configured to be in contact with the movement stopper 10.
According to an example, the three phase earthing switch comprises at least one spring 9. Activation of the at least one spring is configured to transition the three phase earthing switch from the first mode of operation to the second mode of operation.
According to an example, a first end of the at least one spring is connected to the at least one base unit and configured to rotate with respect to the at least one base unit. When the at least one spring is activated a second end of the at least one spring is configured to interact with at least one of the three connectors to rotate the three connectors.
Fig. 2 shows a method 100 of providing a three phase earthing switch in its basic steps. The method 100 comprises:

in a holding step 110, also referred to as step a), holding three connectors 4 by at least one base unit 1, wherein a first distil end each of the three connectors can rotate with respect to the at least one base unit, and wherein a second distil end each of the three connectors comprises a contact knife;
in a mounting step 120, also referred to as step b), mounting three earth contacts 12 at three locations that are mechanically independent from and spaced from the at least one base unit; and

In an example, the three locations of the earth contacts are adjustable to vary the spacing from the at least one base unit.
In an example, each of the three earth contacts has a recess configured to receive a contact knife.
In an example, the at least one base unit is formed from three base units, wherein each connector is held by and configured to rotate with respect to a corresponding base unit. The three connectors are in electrical connection with each other, and wherein the three base units are mounted at three locations spaced from each other.
In an example, at least two locations of two of the three base units are adjustable to vary the spacing between the three base units.
In an example, a first exchangeable interconnecting bar is electrically connects a first one of the three base units to a second one of the three base units, and wherein a second exchangeable interconnecting bar electrically connects the second one of the three base units to a third one of the three base units.
In an example, wherein the method comprises holding an exchangeable shaft by the at least one base unit.
In an example, the method comprises fixedly holding the shaft by the at least one base unit, and wherein the three connectors can rotate with respect to the shaft.
In an example, the method comprises movably holding the shaft by the at least one base unit, where the shaft can rotate with respect to the at least one base unit, and fixedly connecting the three connectors to the shaft.
In an example, the method comprises using a position indicator associated with the shaft to indicate when the three phase earthing switch is in the second mode of operation.
In an example, the method comprises using movement limiting means.
In an example, using the movement limiting means comprises fixedly attaching at least one movement stopper to the at least one base unit, and comprises fixedly attaching at least one movement limiting component to at least one of the three connectors. In transitioning from the first mode of operation to the second mode of operation at least a first part of the at least one movement limiting component moves toward the at least one movement stopper.
In an example, in the second mode of operation the at least first part of the at least one movement limiting component comes into contact with the movement stopper.
In an example, in transitioning from the second mode of operation to the first mode of operation at least a second part of the at least one movement limiting component moves toward the at least one movement stopper.
In an example, in the first mode of operation the at least second part of the at least one movement limiting component is in contact with the movement stopper.
In an example, comprising using at least one spring, wherein activating the at least one spring causes the three phase earthing switch to transition from the first mode of operation to the second mode of operation.
In an example, a first end of the at least one spring is connected to the at least one base unit and can rotate with respect to the at least one base unit. Activation of the at least one spring causes a second end of the at least one spring to interact with at least one of the three connectors to rotate the three connectors.
Fig. 3 shows a detailed example of a three phase earthing switch 50, with Figs. 4 and 5 showing a base unit of the three base units, where moving parts are shown in Fig. 5. The three phase earthing switch has three base units 1, made of bent sheet metal angles 11. The distance between the base units can be selected as necessary. The base units hold the moving parts of the three phase earthing switch. The moving parts are comprised of a shaft 2, movement limiting components 3, an moving contacts (knives 4), moving contact holders 5, interconnecting bars 6, and earthing wires 7. The shaft and interconnecting bars have lengths that are given by the distance between the base units (phase pitch). The interconnecting bars and moving contacts (knives) are made from copper and have a flat profile. A position indicator 8 is mounted on the shaft. The moving parts are driven by a set of springs 9, in order that appropriate closing force and speed is achieved. The end positions are set by the movement stopper 10 working in conjunction with the movement limiting components 3, shown in more detail in Fig. 6 below. In this way, by having free fixing points the phase pitch can be changed easily - base units and earthing contacts can be moved and phase interconnecting bars and shaft can be easily changed with this adjustment. Only one moving contact is required per phase, its design is rigid (3 fixing points), and it used flat Copper phase interconnecting bars and as such is cost effective. Thus ease of assembly and functional settings is provided, with rigidness and improved performance.
Fig. 6 shows the movement limitation principle of the three phase earthing switch, with the earthing switch shown in an open state on the left and in a closed state on the right.
It has to be noted that embodiments of the invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method type claims whereas other embodiments are described with reference to the device type claims. However, a person skilled in the art will gather from the above and the following description that, unless otherwise notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters is considered to be disclosed with this application. However, all features can be combined providing synergetic effects that are more than the simple summation of the features.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing a claimed invention, from a study of the drawings, the disclosure, and the dependent claims.
In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items re-cited in the claims. The mere fact that certain measures are re-cited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

A three phase earthing switch (50), comprising:
- at least one base unit (1);

- three connectors (4); and

- three earth contacts (12);
wherein, the at least one base unit is configured to hold the three connectors,
wherein a first distil end of each of the three connectors is configured to rotate with respect to the at least one base unit;
wherein, a second distil end of each of the three connectors comprises a contact knife;
wherein, the three earth contacts are configured to be mounted at three locations that are mechanically independent from and spaced from the at least one base unit; and
wherein, in a first mode of operation the three connectors are not in contact with the three earth contacts; and
wherein, in a second mode of operation the three connectors are moved such that the three contact knifes are in contact with the three earth contacts.
Three phase earthing switch according to claim 1, wherein the three locations of the earth contacts are adjustable to vary the spacing from the at least one base unit.
Three phase earthing switch according to any of claims 1-2, wherein each of the three earth contacts has a recess configured to receive a contact knife of a connector.
Three phase earthing switch according to any of claims 1-3, wherein the at least one base unit is formed from three base units, wherein each connector is held by and configured to rotate with respect to a corresponding base unit, wherein the three connectors are electrically connected, and wherein the three base units are configured to be mounted at three locations spaced from each other.
Three phase earthing switch according to claim 4, wherein at least two locations of two of the three base units are adjustable to vary the spacing between the three base units.
Three phase earthing switch according to any of claims 4-5, wherein a first exchangeable interconnecting bar (6) is configured to electrically connect a first one of the three base units to a second one of the three base units, and wherein a second exchangeable interconnecting bar (6) is configured to electrically connect the second one of the three base units to a third one of the three base units.
Three phase earthing switch according to any of claims 1-6, comprising an exchangeable shaft (2) that is held by the at least one base unit.
Three phase earthing switch according to claim 7, wherein the shaft is fixedly held by the at least one base unit, and wherein the three connectors are configured to rotate with respect to the shaft.
Three phase earthing switch according to claim 7, wherein the shaft is configured to rotate with respect to the at least one base unit, and wherein the three connectors are fixedly connected to the shaft.
Three phase earthing switch according to claim 9, wherein a position indicator (8) associated with the shaft is configured to indicate when the three phase earthing switch is in a position associated with the second mode of operation.
Three phase earthing switch according to any of claims 1-10, wherein the earthing switch comprises movement limiting means (3, 10).
Three phase earthing switch according to claim 11, wherein the movement limiting means comprises at least one movement stopper (10) fixedly attached to the at least one base unit, and comprises at least one movement limiting component (3) fixedly attached to at least one of the three connectors, wherein in a transition from the first mode of operation to the second mode of operation at least a first part of the at least one movement limiting component is moved toward the at least one movement stopper.
Three phase earthing switch according to claim 12, wherein in the second mode of operation the at least first part of the at least one movement limiting component is configured to be in contact with the movement stopper.
Three phase earthing switch according to any of claims 12-13, wherein in a transition from the second mode of operation to the first mode of operation at least a second part of the at least one movement limiting component is moved toward the at least one movement stopper.
Three phase earthing switch according to claim 14, wherein in the first mode of operation the at least second part of the at least one movement limiting component is configured to be in contact with the movement stopper.
Three phase earthing switch according to any of claims 1-15, comprising at least one spring (9), wherein activation of the at least one spring is configured to transition the three phase earthing switch from the first mode of operation to the second mode of operation.
Three phase earthing switch according to claim 16, wherein a first end of the at least one spring is connected to the at least one base unit and configured to rotate with respect to the at least one base unit, and wherein when the at least one spring is activated a second end of the at least one spring is configured to interact with at least one of the three connectors to rotate the three connectors.
A method (100) of providing a three phase earthing switch, comprising:
a) holding (110) three connectors (4) by at least one base unit (1), wherein a first distil end each of the three connectors can rotate with respect to the at least one base unit, and wherein a second distil end each of the three connectors comprises a contact knife;

b) mounting (120) three earth contacts (12) at three locations that are mechanically independent from and spaced from the at least one base unit; and
wherein the method of providing a three phase earthing switch comprises two modes of operation:
in a first mode of operation the three connectors are not in contact with the three earth contacts; and

in a second mode of operation the three connectors are moved such that the three contact knifes are in contact with the three earth contacts.