EP3161845B1

EP3161845B1 - Static arc-striking contact assembly and grounding switch thereof

Info

Publication number: EP3161845B1
Application number: EP15731362.8A
Authority: EP
Inventors: Hui Wang
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2014-06-26
Filing date: 2015-06-25
Publication date: 2018-06-06
Anticipated expiration: 2035-06-25
Also published as: PL3161845T3; RU2016150843A3; EP3161845A1; RU2016150843A; WO2015197785A1; CN105225883B; RU2669703C2; CN105225883A

Description

Technical field

The present invention relates to a grounding switch employing a static arcing contact assembly.

Background art

A high-voltage switch in an electrical power system, such as an isolating switch for power transmission and transformation, has a grounding switch incorporated therein. A grounding switch is a mechanical switch for a grounded part of a circuit, and must be able to bear current under abnormal conditions for a given period of time, but need not bear current in normal operation. During overhaul of electrical equipment, a grounding switch must be closed in each direction in which electricity might be delivered to powered-off equipment if there is a possibility that it might produce an induced voltage, in order to prevent a sudden return of power during overhaul from endangering the life of associated personnel. Conventional grounding switches are not required to have an arcing device. However, as electrical power systems have developed, power transmission and transformation at ultra-high voltages has been vigorously popularized. In order to solve the problem of ever scarcer power transmission and transformation corridors, double-circuit power transmission lines are often used. Since the distance between conductive wires in a double-circuit power transmission line is very short, significant electromagnetic and electrostatic coupling exists between conductive wires and between conductive wire and ground. To ensure reliability and safety during overhaul, it is required that grounding switches used on the line have the ability to switch induced current, therefore an arcing device must be provided.
Chinese utility model patent CN201804780 has disclosed a high-voltage grounding switch arcing device, wherein an arcing contact is installed below a grounding contact, and an arcing plate is provided on a grounding contact finger. During closing of the grounding switch, an arc is produced between the arcing contact and the arcing plate which come into contact first, with the grounding contact and the grounding contact finger coming into contact subsequently. Such a high-voltage grounding switch arcing device can satisfy technical requirements at lower voltage ratings, but in the case of higher voltage ratings, such as voltage ratings of about 500 kV and above, associated problems such as insufficient insulation distance may occur.
Prior art is disclosed in US3064107A , US2562027A , US1955337A and US2344113A . In particular, US 3 064 107 A discloses a grounding switch (one of the terminals could be connected to ground), comprising an insulator (20), a wiring terminal (33, 34), a static contact (18, 30, 32), a moving contact (12), a moving arc-striking contact (52), and a static arc-striking contact assembly (11) as claimed in claims 1, wherein the wiring terminal (33, 34) is fixed to the top of the insulator (20, see column 2, lines 10-16), the positions of the moving contact (142) and the moving arc-striking contact (141) corresponding to the static contact (12) and the static arc-striking contact assembly (11), respectively; wherein during closing of the grounding switch, the moving arc-striking contact (52) and the static arc-striking contact assembly (52) come into contact before the static contact (18) and the moving contact (12); and wherein during opening of the grounding switch, the moving arc-striking contact (152) and the static arc-striking contact assembly (52) separate after the static contact (18) and the moving contact (12).

Content of the invention

An object of the present invention is to provide a grounding switch, which can be used for higher voltage ratings, operates reliably, and has low costs. This object is achieved by a grounding switch according to claim 1. The wiring terminal and static arcing contact assembly of such a grounding switch have a simple structure and low costs, and operate reliably, and the static arcing contact assembly can be conveniently installed independently of main contacts of the switch, and is especially suitable for switches having high voltage ratings. According to one aspect of the grounding switch of the present invention, said end of the static arcing contact is fixed to the shaft, the shaft is rotatably connected to the housing, and the spring causes the static arcing contact to be deflected towards one side of the opening by restricting the rotation of the static arcing contact. The application of force to the static arcing contact by the spring not only ensures that the arcing contacts come into contact before the main contacts, but also ensures reliable contact therebetween.
According to another aspect of the grounding switch of the present invention, the housing consists of two half-shells, with two spacer blocks being provided between the two half-shells, and the two half-shells being fixed to the two spacer blocks. The combination of the two half-shells and the spacer blocks facilitates assembly of the static arcing contact assembly.
According to another aspect of the grounding switch of the present invention, a ball head is fixed to another end of the static arcing contact. The ball head helps to reduce or eliminate the effect of discharge from a possible pointed end on normal operation of the switch.
According to another aspect of the grounding switch of the present invention, the static arcing contact assembly further comprises an insulating sleeve fixed to the static arcing contact. The insulating sleeve ensures that current no longer flows through the movable arcing contact and static arcing contact once the main contacts are connected. According to another aspect of the grounding switch of the present invention, the grounding switch further comprises a conductive braid which connects the housing and the static arcing contact electrically. The conductive braid helps to make the electrical connection between the housing and the static arcing contact reliable.
According to one aspect of the grounding switch of the present invention, the position of the insulating sleeve is set such that during closing of the grounding switch, the movable arcing contact slides along the surface of the static arcing contact after coming into contact with the static arcing contact, until the static contact and the movable contact have come into proper contact, and then the movable arcing contact remains on the insulating sleeve; when the process of opening the grounding switch begins, the movable arcing contact and the static arcing contact immediately reestablish contact, and only separate once the static contact and the movable contact have completely separated. Setting the position of the insulating sleeve in this way ensures that current no longer flows through the arcing contacts once the main contacts are connected.
According to another aspect of the grounding switch of the present invention, the wiring terminal comprises a connecting arm, a wiring plate and a pedestal, the connecting arm being fixed between the wiring plate and the pedestal, one end of the connecting arm being connected to the static arcing contact assembly, the static contact being fixed to the connecting arm and disposed close to the static arcing contact assembly, and the pedestal being fixed to the insulator. The pedestal helps to ensure creepage distance between the insulator and other parts of the switch.
According to another aspect of the grounding switch of the present invention, the connecting arm is welded to the wiring plate, and the wiring plate is fixed to the pedestal by means of at least one sleeve, said one end of the connecting arm being connected to one of the equalizing rings by means of the static arcing contact assembly, and another end of the connecting arm being connected to the other of the equalizing rings. Welded and connected wiring terminals have lower costs and operate reliably.
The explanation above is merely an overview of the technical solution of the present invention. Preferred embodiments are given below and explained in detail in conjunction with the accompanying drawings, to enable the technical approach of the present invention to be understood more clearly and implemented according to the content of the description, and to enable the abovementioned and other objects, features and advantages of the present invention to be more obvious and easy to understand.

Description of the accompanying drawings

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, to give those skilled in the art a clearer understanding of the abovementioned and other features and advantages of the present invention. Specifically:

Fig. 1 is a three-dimensional schematic diagram of a grounding switch according to an embodiment of the present invention;
Fig. 2 is an exploded schematic diagram of the grounding switch in Fig. 1 ;
Fig. 3 is an exploded schematic diagram of the wiring terminal in Fig. 1 ;
Fig. 4 is an exploded schematic diagram of the static arcing contact assembly in Fig. 1 ;
Fig. 5 further displays the static arcing contact assembly in Fig . 4.

Key to labels in the accompanying drawings:

1	grounding switch	13	wiring terminal
11	static arc-striking contact assembly	1311, 1312	connecting arm ends
111	housing	132	wiring plate
112	shaft	1322	hole
113	static arc-striking contact	133	pedestal
114	spring	134	sleeve
115	spacer block	14	rod
116	ball head	141	moving arc- striking contact
1111, 1112	holes	142	moving contact
12	static contact	143	moving arc-striking contact connecting piece
121	static contact body	151, 152	equalizing ring
122	static contact connecting piece	153	insulator
131	connecting arm	117	conductive braid
		118	insulating sleeve

Particular embodiments

The present invention is explained in further detail below by way of embodiments, to clarify the object, technical solution and advantages thereof.
Figs. 1 and 2 display the grounding switch 1 of the present invention, which has a static arcing contact assembly 11 as shown in Figs. 4 and 5. The static arcing contact assembly 11 comprises a housing 111, a shaft 112, a static arcing contact 113 and a spring 114, wherein the housing 111 has an opening. One end of the static arcing contact 113 extends into the opening and is rotatably connected to the housing 111 by means of the shaft 112. A ball head 116 is fixed to the other end of the static arcing contact 113. The ball head 116 is generally made of metal, and helps to reduce or eliminate the effect of discharge from a possible pointed end on normal operation of the switch. In addition, those skilled in the art will understand that the same or a similar effect could also be achieved by setting the shape of the other end of the static arcing contact 113, rather than by means of the ball head 116. The spring 114 is connected to the housing 111 and causes the static arcing contact 113 to be deflected towards one side of the opening.
The end of the static arcing contact 113 that extends into the opening may be fixed to the shaft 112, e.g. fixed to a middle part of the shaft 112 by a snap connection or a threaded connection (e.g. by fitting a nut to a thread on the static arcing contact 113) , with the shaft 112 being rotatably connected to the housing 111, e.g. if the two ends of the shaft 112 as shown in Fig. 5 have bosses for insertion into holes 1112 in the housing 111, then axial movement of the shaft 112 can be restricted after installation without the need for any additional component. The spring 114 causes the static arcing contact
113 to be deflected towards one side of the opening by restricting the rotation of the static arcing contact 113, but the method (not shown) of restricting rotation of the shaft 112 could also be employed to cause the static arcing contact 113 to be deflected towards one side of the opening. The spring 114 may be a torsion spring, but may also be another spring capable of realizing the same function. As Fig. 4 shows, the housing 111 consists of two half-shells, with two spacer blocks 115 being provided between the two half-shells, wherein the two half-shells are fixed to the two spacer blocks 115 by means of bolts or screws (not shown) passing through holes 1111 in the half-shells, and when necessary further fixed to one end 1311 of a connecting arm 131 of a wiring terminal 13 on the grounding switch 1. The half-shells and spacer blocks are all of metal material. In an embodiment of the present invention which is not shown, the housing 111 may also take another form, e.g. a one-piece element formed by casting so as to include the half- shells and the spacer blocks.
The static arcing contact assembly 11 may further comprise an insulating sleeve 118. The insulating sleeve 118 is fixed to the static arcing contact 113, and used to realize insulation between a movable arcing contact 141 and the static arcing contact 113 once a static contact 12 and a movable contact 142 are in proper contact, so as to ensure that current no longer flows through the movable arcing contact 141 and static arcing contact 113 once the main contacts are connected, but the insulating sleeve 118 is not necessary.
Figs. 1 and 2 show a grounding switch 1. The grounding switch 1 comprises an insulator 153, a wiring terminal 13, a static contact 12, a movable contact 142, a movable arcing contact 141, two equalizing rings 151 and 152, and a static arcing contact assembly 11 as described above, wherein the wiring terminal 13 is fixed to the top of the insulator 153. The static arcing contact assembly 11 is connected between one side of the wiring terminal 13 and equalizing ring 151, more specifically connected between one end 1311 of the connecting arm 131 and equalizing ring 151 by means of the holes 1111 in the housing 111, and equalizing ring 152 is connected on the other side of the wiring terminal 13. The movable arcing contact 141 is fixed to a rod 14 by means of a movable arcing contact connecting piece 143, and is kept at a suitable distance from the movable contact 142. The static contact 12 is connected between the wiring terminal 13 and the static arcing contact assembly 11. The positions of the movable contact 142 and movable arcing contact 141 correspond to the static contact 12 and the static arcing contact assembly 11, respectively. During closing of the grounding switch 1, the movable arcing contact 141 and static arcing contact assembly 11 come into contact before the static contact 12 and movable contact 142. During opening of the grounding switch 1, the movable arcing contact 141 and static arcing contact assembly 11 separate after the static contact 12 and movable contact 142. Since the spring 114 causes the static arcing contact 113 to be deflected towards the side of the opening which faces the movable arcing contact 141, the distance between the movable arcing contact 141 and static arcing contact assembly 11 is smaller than the distance between the static contact 12 and movable contact 142; therefore during closing of the grounding switch, the movable arcing contact 141 and static arcing contact assembly 11 come into contact first relative to the static contact 12 and movable contact 142, but separate later during opening of the grounding switch, thereby avoiding ablation of the static contact 12 and movable contact 142 by an arc during this process. Moreover, since a suitable distance is maintained between the arcing contacts (i.e. the movable arcing contact 141 and static arcing contact 113) and the main contacts (i.e. the static contact 12 and movable contact 142), breakdown and/or ablation therebetween is avoided to the greatest extent possible.
In an embodiment in which the static arcing contact assembly 11 comprises an insulating sleeve 118, the position of the insulating sleeve 118 is set such that during closing of the grounding switch 1, the movable arcing contact 141 slides along the surface of the static arcing contact 113 after coming into contact with the static arcing contact 113, until the static contact 12 and movable contact 142 have come into proper contact, and then the movable arcing contact remains on the insulating sleeve 118. When the process of opening the grounding switch 1 begins, the movable arcing contact 141 and static arcing contact 113 immediately re-establish contact, and only separate once the static contact 12 and movable contact 142 have completely separated. Thus it is ensured that current no longer flows through the arcing contacts once the main contacts are connected. Since the spring 114 causes the static arcing contact 113 to be deflected towards the side of the opening which faces the movable arcing contact 141, there is always an action/reaction force pair between the movable arcing contact 141 and static arcing contact 113 throughout the process of contact between the movable arcing contact 141 and static arcing contact 113, so that reliable contact is ensured between the movable arcing contact 141 and static arcing contact 113.
Fig. 3 further displays the wiring terminal 13. The wiring terminal 13 comprises a connecting arm 131, a wiring plate 132 and a pedestal 133, wherein the connecting arm 131 and wiring plate 132 may be made of aluminium, while the pedestal 133 may be made of steel. Holes 1322 in the wiring plate 132 are used for further wiring of the wiring terminal 13. The connecting arm 131 is fixed between the wiring plate 132 and pedestal 133, while the pedestal 133 is fixed to the insulator 153 by bolts (not shown) . One end 1311 of the connecting arm 131 is connected to the static arcing contact assembly 11. A body 121 of the static contact 12 is fixed to the connecting arm 131 by means of a static contact connecting piece 122 and disposed close to the static arcing contact assembly 11. The connecting arm 131 may be connected to the wiring plate 132 by welding, but may also be riveted or connected by bolts. The wiring plate 132 may be fixed to the pedestal 133 by bolts (not shown) passing through four sleeves 134 as shown in Fig. 3, or in an embodiment which is not shown, fixed by means of one sleeve having a number of holes; alternatively, the connecting arm, wiring plate and pedestal may be made as one integrally cast component, but a welded or connected wiring terminal has a lower cost, and can be installed with greater flexibility and convenience. One end 1311 of the connecting arm 131 is connected to equalizing ring 151 by means of the static arcing contact assembly 11, while another end 1312 of the connecting arm 131 is connected to equalizing ring 152 directly.
During closing of the grounding switch of the present invention, the movable arcing contact 141 which is fixed to the movable contact 142 approaches the static arcing contact 113 of the static arcing contact assembly 11 first, so that the movable contact 142 only comes into contact with the static contact 12 once the movable arcing contact 141 has come into contact with the static arcing contact 113. During opening of the grounding switch of the present invention, the movable contact 142 breaks contact with the static contact 12 first, and the movable arcing contact 141 only breaks contact with the static arcing contact 113 when the movable contact 142 has reached a certain distance from the static contact 12; before the movable arcing contact 141 and static arcing contact 113 are completely disconnected, an arc forms therebetween. The grounding switch of the present invention has a simple structure and operates reliably, and thereby realizes reliable closing and disconnection of the grounding switch at a low cost, avoiding ablation of the movable contact and static contact by an arc.
The above embodiments are merely preferred embodiments of the present invention, which are not intended to limit it.

Claims

A grounding switch, comprising an insulator (153), a wiring terminal (13), a static contact (12), a movable contact (142), a movable arcing contact (141), two equalizing rings (151, 152), and a static arcing contact (11), wherein the static arcing contact (11) comprising a housing (111), a shaft (112), a static arcing contact (113) and a spring (114), wherein the housing (111) has an opening, one end of the static arcing contact (113) extends into the opening and is rotatably connected to the housing (111) by means of the shaft (112), the spring (114) is connected to the housing (111) and causes the static arcing contact (113) to be deflected towards one side of the opening; the wiring terminal (13) is fixed to the top of the insulator (153), the static arcing contact (11) is connected between one side of the wiring terminal (13) and one (151) of the equalizing rings, and the other (152) of the equalizing rings is connected on the other side of the wiring terminal (13); the static contact (12) is connected between the wiring terminal (13) and the static arcing contact (11), the positions of the movable contact (142) and the movable arcing contact (141) correspond respectively to the static contact (12) and the static arcing contact (11);
during closing of the grounding switch (1), the movable arcing contact (141) and the static arcing contact (11) come into contact before the static contact (12) and the movable contact (142); during opening of the grounding switch (1), the movable arcing contact (141) and the static arcing contact (11) separate after the static contact (12) and the movable contact (142).
The grounding switch as claimed in claim 1, wherein said end of the static arcing contact (113) is fixed to the shaft (112), the shaft (112) is rotatably connected to the housing (111), and the spring (114) causes the static arcing contact (113) to be deflected towards one side of the opening by restricting the rotation of the static arcing contact (113).
The grounding switch as claimed in claim 2, wherein the housing (111) consists of two half-shells, with two spacer blocks (115) being provided between the two half- shells, and the two half-shells being fixed to the two spacer blocks (115).
The grounding switch as claimed in claim 3, wherein a ball head (116) is fixed to another end of the static arcing contact (113) .
The grounding switch as claimed in claim 4, wherein the static arcing contact (11) further comprises an insulating sleeve (118) fixed to the static arcing contact (113).
The grounding switch as claimed in claim 5, wherein the grounding switch further comprises a conductive braid (117) which connects the housing (111) and the static arcing contact (113) electrically.
The grounding switch as claimed in claim 6, wherein the position of the insulating sleeve (118) is set such that during closing of the grounding switch (1), the movable arcing contact (141) slides along the surface of the static arcing contact (113) after coming into contact with the static arcing contact (113), until the static contact (12) and the movable contact (142) have come into proper contact, and then the movable arcing contact remains on the insulating sleeve (118); when the process of opening the grounding switch (1) begins, the movable arcing contact (141) and the static arcing contact (113) immediately re-establish contact, and only separate once the static contact (12) and the movable contact (142) have completely separated.
The grounding switch as claimed in any one of claims 1 to 7, wherein the wiring terminal (13) comprises a connecting arm (131), a wiring plate (132) and a pedestal (133), the connecting arm (131) being fixed between the wiring plate (132) and the pedestal (133), one end (1311) of the connecting arm (131) being connected to the static arcing contact (11), the static contact (12) being fixed to the connecting arm (131) and disposed close to the static arcing contact (11), and the pedestal (133) being fixed to the insulator (153) .
The grounding switch as claimed in claim 8, wherein the connecting arm (131) is welded to the wiring plate (132), and the wiring plate (132) is fixed to the pedestal (133) by means of at least one sleeve (134), said one end (1311) of the connecting arm (131) being connected to one (151) of the equalizing rings by means of the static arcing contact (11), and another end (1312) of the connecting arm (131) being connected to the other (152) of the equalizing rings.