WO2020161536A1

WO2020161536A1 - Switchgear contact assembly with modular finger holders

Info

Publication number: WO2020161536A1
Application number: PCT/IB2019/058725
Authority: WO
Inventors: Shashwat CHAUHAN; Ajit KADAM
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2018-11-21
Filing date: 2019-10-14
Publication date: 2020-08-13
Anticipated expiration: 2021-05-21
Also published as: CN217333860U; JP3235099U

Abstract

The invention relates to a switchgear with a contact assembly for performing a switching operation. The contact assembly comprises a main contact with a first and a second set of contact fingers. The contact assembly further comprises a housing. The main contact is mounted on the housing. The housing has at least two planar surfaces. Each planar surface is provided for mounting of at least one set of contact fingers. The contact assembly has at least two finger holders. Each finger holder mounts contact fingers of a set of contact fingers, and comprises at least two holding plates. At least one contact finger of the set is mounted using two holding plates of the finger holder. Here, a first portion of the contact finger is mounted using one holding plate and a second portion of the contact finger is mounted using another holding plate.

Description

SWITCHGEAR CONTACT ASSEMBLY WITH MODULAR FINGER

HOLDERS

FIELD OF THE INVENTION

[001] The present invention generally relates to switchgear such as disconnectors or earth switches. More specifically, the present invention relates to switchgear contact assemblies having modular finger holders.

BACKGROUND OF THE INVENTION

[002] Switchgear such as disconnector, earth switches, or isolators, have different configurations. For example, there are single break, double break, side break, center break type switches and so forth. Taking another example, there are turn and twist type, knee type disconnectors and so forth.

[003] These switchgear typically have contacts for electrical current conduction, including contact fingers. These contact fingers are usually mounted together to form a main contact For instance pairs of contact fingers can be mounted to form a fixed contact.

[004] The contact fingers are usually mounted on some components of the switchgear such as for example on a current path pipe or a casting or housing, using support plates or frames. Most often the supporting plates are rectangular plates that are affixed to the current path pipe / casting / housing using some fixing mechanism (e.g. screws).

[005] When such supporting plates are used for mounting more number of contact fingers, some contact fingers do not get the required support. For example, when a rectangular plate is used to mount three contact fingers, one or more contact fingers may not receive the tightening torque. This can cause the finger(s) to become loose, leading to failure of the contact and the switchgear.

SUMMARY OF THE INVENTION

[006] The present invention provides a switchgear for electrical connection and disconnection. Examples of the switchgear include disconnector, isolator or earth switches. The switchgear has a contact assembly for performing a switching operation. For example, the switchgear has a contact assembly for electrical current conduction at high voltages. For electrical connection, there can be a fixed contact and a moving contact. [007] Depending on the configuration of the switchgear, one or more contact assemblies includes a main contact with two sets of contact fingers. Here, the main contact includes a first set of contact fingers and a second set of contact fingers. The contact fingers are used for electrical current conduction. The contact assembly further includes a housing. [008] The main contact is mounted on the housing. The housing has at least two (two or more) planar surfaces for mounting of the contact fingers. For example, the housing can be part of a fixed contact, and includes two planar surfaces for mounting of contact fingers in a particular orientation (e.g. horizontally with respect to ground and the two sets of contact fingers being at different levels). Taking another example, the housing can be part of a cylindrical pipe that is provided for mounting of the contact fingers in another orientation (e.g. horizontally with respect to ground and the two sets of contact fingers being at the same level).

[009] Each planar surface is provided for mounting of at least one of the first and second set of the contact fingers using one or more finger holders. For example one planar surface is for mounting of the first set, and another planar surface is for mounting of the second set For example, one planar surface is provided for mounting one set of contact fingers, and another planar surface is provided for mounting of another set of contact fingers. These planar surfaces are provided such that the two sets of contact fingers can be mounted in the desired orientation to form the main contact.

[0010] In accordance with some embodiments, each planar surface of the housing comprises a plurality of grooves for mounting of contact fingers of the corresponding set of contact fingers of the main contact. Each groove can have a suitable shape (e.g. semi-cylindrical) for receiving a contact finger. Thus, a planar surface can have several grooves for accommodating contact fingers of a set. [0011] In accordance with various embodiments, each planar surface has through holes with internal threads or other suitable openings for receiving at least one (one or more) fasteners. For example, a planar surface can have two or more through holes.

[0012] The contact assembly has at least two (two or more) finger holders. For example, the contact assembly has two finger holders. Each finger holder mounts two or more contact fingers of the corresponding set of contact fingers on the housing. For example, one finger holder mounts all the contact fingers of the first set of contact fingers and another finger holder mounts all the contact fingers of the second set of contact fingers. Taking another example, two finger holders are used for mounting all the contact fingers of the first set of contact fingers.

[0013] Each finger holder has at least two holding plates for mounting of the two or more contact fingers. In accordance with some embodiments, each holding plate is attached with the housing using at least one fastener for mounting of the corresponding contact fingers. The at least one fastener can be attached with the housing at a through hole provided on a corresponding planar surface of the housing. For example, two screws (or other suitable fasteners) can be provided for each holding plate, and the same can be screwed into the through holes provided on the housing for mounting of the contact fingers.

[0014] In accordance with various embodiments, each holding plate comprises a step. Here, the at least two holding plates of the finger holder are combined at the steps for mounting of the two or more contact fingers. For example, the finger holder has two holding plates, and each plate has one step. Here, the two plates can be combined at the step to form the finger holder for mounting of the contact fingers.

[0015] In the contact assembly, at least one contact finger is mounted using at least a first and a second holding plate of the at least two holding plates. Here, a first portion of the at least one contact finger is mounted using the first holding plate and a second portion of the at least one contact finger is mounted using the second holding plate.

[0016] For example, at least one finger holder of the contact assembly can be used to mount three contact fingers. Here, the first holding plate mounts a first contact finger at the first portion. Further, the first holding plate mounts the first contact finger and a second contact finger at the second portion. Further, the second holding plate mounts the second contact finger and a third contact finger at the first portion, and the third contact finger at the second portion. [0017] In accordance with some embodiments, at least two holding plates of at least one finger holder are identical. In accordance with the example for mounting of three contact fingers, the first holding plate is identical to the second holding plate. Here, each plate comprises a step, and the two holding plates are combined at the steps for mounting of the three contact fingers. [0018] In some embodiments, at least one finger holder of the at least two finger holders mounts four or more contact fingers. Here, the at least one finger holder comprises at least two holding plates of a first type and at least one holding plate of a second type. For example, there can be two holding plates of the first type, and one holding plate of the second type when used for mounting four contact fingers. Taking another example, there can be two holding plates of the first type and two holding plates of the second type when used for mounting five contact fingers.

[0019] In accordance with these embodiments, each contact finger is mounted with one of a holding plate of the first type, a holding plate of the first type and a holding plate of the second type, and at least two holding plates of the second type. For example, a contact finger can be mounted using one holding plate of the first type. Taking another example, a contact finger can be mounted using one holding plate of the first type and one holding plate of the second type. Taking yet another example, a contact finger can be mounted using two holding plates of the second type.

[0020] Thus, the contact assembly has two or more finger holders that are modular. In other words, the finger holder has pieces (holding plates) combined according to the number of contact fingers. The holding plates can be combined in different number to form the finger holder, according to the number of contact fingers.

BRIEF DESCRIPTION OF DRAWINGS [0021] The subject matter of the invention will be explained in more detail in the following text with reference to exemplary embodiments which are illustrated in attached drawings in which:

[0022] Fig. 1 shows a contact assembly of a switchgear; [0023] Fig. 2 shows an enlarged perspective view of the contact assembly of Fig. 1;

[0024] Fig. 3 shows a contact assembly of another switchgear;

[0025] Fig. 4 shows a contact assembly of a switchgear, in accordance with an embodiment of the present invention;

[0026] Fig. 4 shows a contact assembly of a switchgear, in accordance with an embodiment of the present invention;

[0027] Fig. 5 shows a housing of the contact assembly, in accordance with an embodiment of the present invention;

[0028] Fig. 6 shows a housing of a contact assembly of another switchgear, in accordance with an embodiment of the present invention; [0029] Fig. 7 shows the contact assembly of the switchgear, in accordance with another embodiment of the present invention;

[0030] Figs. 8 and 9 are perspective views of the contact assembly of the switchgear shown in Fig. 4; and

[0031] Fig. 10 is a perspective view of the contact assembly of the switchgear shown in Fig. 7.

DETAILED DESCRIPTION

[0032] The present invention relates to switchgear for electrical connection and disconnection. The switchgear can be, but need not be limited to, a disconnector, an isolator or earth switches. The switchgear has a contact assembly for performing a switching operation. For example, the switchgear has a contact assembly for electrical current conduction at high voltages. For electrical connection, there can be a fixed contact and a moving contact

[0033] Referring to Figs. 1 to 3, which illustrate a contact assembly of a disconnector. The disconnector can be of any type or configuration. In Fig. 1, the contact assembly is of a side break or double break disconnector, while Fig. 3 shows the contact assembly of a center break disconnector.

[0034] As shown in Figs. 1 and 3, the contact assembly has a main contact that includes two sets of contact fingers as shown by 102, 104. Each set of contact fingers has a plurality of contact fingers. For example, one set of contact fingers can have two contact fingers, three contact fingers (refer Fig. 3), five contact fingers (as in Fig. 1) etc. Each contact finger can be cylindrical. Optionally, a part of the contact finger can be flat (108), for facilitating mounting of the finger.

[0035] As the number of fingers (contact fingers) to hold is increased from two to a higher number, when a finger holder such as 106 shown in Fig. 2 is used, any one or more fingers tend to remain loose in the assembly. This can be attributed to difficulty in manufacturing the surfaces of the housing, contact finger, finger holder etc., required for holding the contact fingers firmly. For example, there can be grooves provided on the housing for mounting of the contact fingers, and it is generally difficult to machine all the grooved surfaces to the same depth. Additionally, or alternately, the fingers can have flat surfaces and the finger widths may be slightly different. Accordingly, all the fingers are not at the same level when mounted using a finger holder such as 106. Due to this, while tightening, only two fingers will get proper holding force and the remaining fingers will be seated loosely in the assembly. For example, the side finger or the center finger can remain loose, while the other two fingers are tightened properly. This can lead to failure of the contact assembly, for example there can be heating of some contact points, due to poor electrical conduction in the loose fingers. There could be formation of hot spots or other problems, which is in general linked to having loose joints in such switchgear.

[0036] The present invention accordingly provides a switchgear which has a contact assembly, where the contact fingers are mounted with the above problem addressed. Depending on the configuration of the switchgear, there could be one or multiple contact assemblies where there are contact fingers mounted with the above problem addressed. Accordingly, one or more contact assemblies of the switchgear include a main contact with two sets of contact fingers such as those, but not limited to, shown in Figs. 1 or Fig. 3. Here, the main contact includes a first set of contact fingers (102) and a second set of contact fingers (104). The contact fingers are used for electrical current conduction. The contact assembly further includes a housing.

[0037] The main contact is mounted on the housing, for example 402 as shown in Fig. 4. The housing has at least two (two or more) planar surfaces for mounting of the contact fingers. As shown in Fig. 5, the housing can be part of a fixed contact, and includes two planar surfaces (502, 504) for mounting of contact fingers in a particular orientation (e.g. horizontally with respect to ground and the two sets of contact fingers being at different levels). Alternately, as shown in Fig. 6, the housing can be part of a cylindrical pipe that is provided for mounting of the contact fingers in another orientation (e.g. horizontally with respect to ground and the two sets of contact fingers being at the same level). In Fig. 6, the housing is provided at an end of the current pipe (refer Fig. 3), and the two planar surfaces (602, 604) are provided for mounting of the two sets of contact fingers.

[0038] Each planar surface is provided for mounting of at least one of the first and second set of the contact fingers using one or more finger holders. For example, one planar surface (such as 502, 602) is provided for mounting one set of contact fingers, and another planar surface (such as 504, 604) is provided for mounting of another set of contact fingers. These planar surfaces are provided such that the two sets of contact fingers can be mounted in the desired orientation to form the main contact. In the embodiments shown in the figures, the contact fingers are mounted in pairs for a side break or a center break operation. There could be various configurations that are not shown, but are readily known to those of ordinary skill in the art, such as for example when mounted in case of a vertical break or a knee type disconnector or earth switch.

[0039] As shown in Figs. 5 and 6, each planar surface of the housing comprises a plurality of grooves (506a, 506b, 506c ... 606a, 606b, 606c ... ) for mounting of contact fingers of the corresponding set of contact fingers of the main contact. While it is shown that the planar surface has grooves in the different figures, it should be noted that the grooves are optional. The contact fingers or the finger holder can have appropriate variations to facilitate mounting, in which case grooves would not be needed on the planar surfaces. In case grooves are provided, such as 506, 606 etc., shown in Figs. 5 and 6, each groove can have a suitable shape (e.g. semi-cylindrical) for receiving a contact finger. Thus, a planar surface can be flat or have several grooves for accommodating contact fingers of a set of contact fingers. The number of grooves depends on the capacity of the contact assembly, e.g. five as shown in Fig. 5, three as shown in Fig. 6.

[0040] In accordance with various embodiments, each planar surface has through holes or other suitable openings for receiving at least one (one or more) fasteners. For example, a planar surface can have two or more through holes with internal threads, such as 510a, 510b; 512a, 512b; ... shown in Fig. 5, or 610a, 610b... shown in Fig. 6. These through holes with internal threads are used for attaching fasteners such as screws. It should be noted that there could be differences in the provision made for attaching such fasteners for mounting the contact fingers. For example, in place of two through holes with internal threads for attaching two screws, one through hole with internal threads can be provided. Such variations in the alternate mechanisms for affixing components on the housing will be apparent to those of ordinary skill in the art.

[0041] The planar surfaces are used for mounting of the main contact on the housing. The finger holders of the present invention are used for mounting the contact fingers on the planar surfaces. In accordance with different embodiments, the contact assembly (or assemblies) of the switchgear has at least two (two or more) finger holders. For example, the contact assembly has two finger holders, as could be the case for a contact assembly similar to that in Fig. 3, but having the finger holder in accordance with the present invention. Taking another example, as shown in Fig. 4, the contact assembly has four finger holders, two finger holders for each set. As shown in Fig. 4, different finger holders can be used for mounting of the contact fingers. In Fig. 4, the modular finger holders (404a, 404b) of the present invention are used along with other finger holders (406a, 406b) for mounting of the main contact. Alternately, as shown in Fig. 7, two modular finger holders (702a, 702b) can be used for mounting of the contact fingers. [0042] Each finger holder mounts two or more contact fingers of the corresponding set of contact fingers on the housing. For example, each finger holder (such as 702a, 702b) mounts all the contact fingers of a set of contact fingers. Taking another example, two finger holders are used for mounting all the contact fingers of a set of contact fingers (such as 404a, 406a; 404b, 406b). [0043] Each finger holder of the present invention has at least two holding plates for mounting of the two or more contact fingers. For example, 404a and 404b have two holding plates (such as hpl, hp2 shown in Fig. 4), 702a, and 702b have five holding plates (such as hpl, hp2, hp3, hp4, hp5 shown in Fig. 7) etc.

[0044] A finger holder of the present invention can have plates of same type, or plates of different types, that can be combined together to form the finger holder. In the embodiment shown by 404a, 404b, the finger holder has two holding plates (i.e. hpl, hp2 shown in Fig. 4) of the same type. In the embodiment shown by 702a, 702b, the finger holder has two holding plates of a first type (such as hpl, hp5 shown in Fig. 7), and three holding plates of a second type (such as hp2, hp3, hp4 shown in Fig. 7). Thus, in accordance with some embodiments, a finger holder of the present invention can be formed by two identical plates, and in accordance with some other embodiments, a finger holder of the present invention can be formed using plates of two types.

[0045] In accordance with various embodiments, each holding plate comprises a step. For example, hpl has a step shown by 802 in Fig. 8, hp2 has a step as shown by 902 in Fig. 9, or hp2 has two steps as shown by 1002 and 1004 in Fig. 10. The at least two holding plates of the finger holder are combined at the steps for mounting of the two or more contact fingers. For example, as shown in Fig. 4, the finger holder has two holding plates, and each plate has one step (such as 802, 902 shown in Figs. 8 and 9). Here, the two plates (hpl, hp2) can be combined at the steps to form the finger holder for mounting of the contact fingers as shown in Fig.4 (404a for example). [0046] The contact fingers are mounted using the holding plates. In accordance with various embodiments, at least one contact finger is mounted using at least a first and a second holding plate of the at least two holding plates. Here, a first portion of the at least one contact finger is mounted using the first holding plate and a second portion of the at least one contact finger is mounted using the second holding plate.

[0047] Consider the finger holder 404a, or 404b. The finger holder (say 404a) of the contact assembly is used to mount three contact fingers (cf1, cf2, cf3 shown in Fig. 8). Here, the first holding plate (hpl) mounts a first contact finger (cf1) at the first portion (804). Further, the first holding plate mounts the first contact finger (cf1) and a second contact finger (cf2) at the second portion (see 806, 808). Further, the second holding plate (hp2 in Fig. 9) mounts the second contact finger (cf2) and a third contact finger (cf3) at the first portion (see 904, 906), and the third contact finger (cf3) at the second portion (908).

[0048] Thus, in this finger holder (i.e. 404a, or 404b) hpl is used to mount cf1 fully and cf2 at a portion (808). Similarly, hp2 is used to mount cf3 fully and cf2 at a portion (904). Thus, at least one contact finger (i.e. cf2 in this case) is mounted using two plates, where one plate mounts one portion and the other plate mounts the other portion.

[0049] Consider the finger holder 702a or 702b. The finger holder (say 702a) mounts six contact fingers. This finger holder comprises two holding plates of a first type (hpl , hp5 of Fig. 7) and three holding plates of a second type (hp2, hp3, hp4). It should be noted that the finger holder can be formed with two holding plates of the first type and one holding plate of the second type, when four fingers are to be supported. Similarly, when five fingers are to be mounted, there can be two holding plates of the second type.

[0050] In this finger holder (such as 702a), each contact finger is mounted with one of a holding plate of the first type, a holding plate of the first type and a holding plate of the second type, and at least two holding plates of the second type. For example, cf1 is mounted using hpl (similar to the case of cf1 in 404a). Taking another example, cf2 is mounted using hpl and hp2. Taking yet another example, cf3 is mounted using hp2 and hp3. The mounting of cf1 and cf6 in Fig. 10 is similar to mounting of cf1 and cf3 shown in Figs. 8 and 9. The contact fingers cf2 to cf5 in Fig. 10 have similar mounting as in case of cf2 of Figs. 8 and 9. The difference is that the holding plate used is slightly different. See for example hp2, hp3, hp4 of Fig.7. These holding plates are designed to have two steps such as 1002 and 1004. One step is used to support a contact finger at the first portion and another step is used to support another contact finger at the second portion. For example, hp2 in Fig. 10 mounts cf2 at the first portion and cf3 at the second portion. The first portion of cf3 is mounted using hp3. For the sake of understanding, some pieces are not shown in Figs. 8 to 10 (e.g. hp2 not shown in Fig. 8, hpl not shown in Fig. 9, and hp3 not shown in Fig. 10).

[0051] These holding plates are attached using one or more fasteners with the housing for mounting of the contact fingers. In the embodiments shown in the figures, each holding plate is attached with the housing using at least one fastener for mounting of the corresponding contact fingers. The at least one fastener can be attached with the housing at a through hole with internal threads (such as 510a, 510b; 610a, 610b etc.) provided on a corresponding planar surface of the housing. As shown in Fig. 4, two screws 408a, 408b (or other suitable fasteners) are provided for each holding plate, and the same can be screwed into the through holes with internal threads (e.g. 510a, 510b) provided on the housing for mounting of the contact fingers. It should be noted that the number of fasteners of the fastening mechanism can be different. For example, one screw and through hole may be used for mounting of one plate in place of two screws / through holes. Taking another example, a clamping arrangement may be provided in place of screws.

[0052] Thus, the holding plates are combined together to mount the contact fingers. In accordance with different embodiments, the contact assembly of the switchgear has two or more finger holders that are modular. In other words, the finger holder has pieces (holding plates) combined according to the number of contact fingers. The holding plates are combined in different number to form the finger holder, according to the number of contact fingers. Each holding plate now focuses on certain contact fingers, and therefore the required tightening torque can be provided on each finger. When the holding plate mounts a finger completely, the complete torque is provided from the holding plate itself. When two holding plates mount a finger, the torque is provided in one part of the finger by one plate, and in another part of the finger by another plate. The stepped construction of the plate enhances the overlap of the plate / holder, thereby providing sufficient coverage of the finger when covered by two plates. As the contact area of each holding plate is less than the contact are of the conventional finger holders, the holding force requirement for each finger is met, thereby minimizing the chances of failures due to loose joints. The finger holder of the present invention gives the flexibility in the assembly of fingers and can be adjusted according to surface irregularities. Additionally, the finger holder assists in overcoming problems due to surface irregularities. As the finger holder has multiple plates as compared to the single piece of conventional finger holders, the effect of surface irregularities are minimized. Each plate of the finger holder adjusts its elevation from the surface at the mating boundary of two plates, thus taking care of the irregularity.

Claims

CLAIMS We Claim

1. A switchgear for electrical connection and disconnection, comprising a contact assembly for performing a switching operation, the contact assembly comprising: a main contact with a first (102) and a second set (104) of contact fingers, for electrical current conduction;

a housing (402), the main contact being mounted on the housing, wherein the housing comprises at least two planar surfaces (502, 504), each planar surface being provided for mounting of at least one of the first and second set of the contact fingers using one or more finger holders; and

at least two finger holders, each finger holder mounting two or more contact fingers of the corresponding set of contact fingers on the housing, and comprising at least two holding plates (hpl , hp2 ...) for mounting of the two or more contact fingers (cf1, cf2 ....), wherein at least one contact finger (cf2) is mounted using at least a first and a second holding plate of the at least two holding plates, wherein a first portion of the at least one contact finger is mounted using the first holding plate and a second portion of the at least one contact finger is mounted using the second holding plate.

2. The switchgear of claim 1, wherein each holding plate comprises a step (802, 902, 1002, 1004), and the at least two holding plates are combined at the steps for mounting of the two or more contact fingers.

3. The switchgear of claim 1 , wherein at least one finger holder of the at least two finger holder mounts three contact fingers (cf1, cf2, cf3), wherein the first holding plate (hpl) mounts a first contact finger (cf1) at the first portion (804) and the first (cf1) and a second contact finger (cf2) at the second portion (806, 808), and wherein the second holding plate (hp2) mounts the second (cf2) and a third contact finger (cf3) at the first portion (904, 906) and the third contact finger (cf1) at the second portion (908).

4. The switchgear of claim 3, wherein the first holding plate is identical to the second holding plate, and each plate comprises a step, and wherein the two holding plates are combined at the steps for mounting of the three contact fingers.

5. The switchgear of claim 1 , wherein at least one finger holder of the at least two finger holders mounts four or more contact fingers, wherein the at least one finger holder comprises at least two holding plates of a first type and at least one holding plate of a second type, wherein each contact finger is mounted with one of:

a holding plate of the first type,

a holding plate of the first type and a holding plate of the second type, and at least two holding plates of the second type.

6. The switchgear of claim 1, wherein each holding plate is attached with the housing using at least one fastener for mounting of the corresponding contact fingers.

7. The switchgear of claim 6, wherein the at least one fastener (408a) is attached with the housing at a through hole with internal threads provided on a corresponding planar surface of the housing.

8. The switchgear of claim 1, wherein each planar surface of the housing comprises a plurality of grooves (506a, 506b, 506c; 602a, 602b, 602c) for mounting of contact fingers of the corresponding set of contact fingers of the main contact.