Knife switch, a switching device comprising a knife switch and a switchgear

Patent metadata

Field	Value
Publication number	US-9466955-B2
Application number	US-201314780450-A
Country	US
Kind code	B2
Filing date	Mar 28, 2013
Priority date	Mar 28, 2013
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

A knife switch including an operator device for moving a contact knife between a first open position and a second position in electrical contact with a contact element. A free end of the contact knife provided with a dynamic electric field control device including an electrically conductive element. A switching device including a two-position switch including an at least partly electrically conductive housing, a three-position switch including the knife switch for connecting the two-position switch to a first electric conductor, wherein the at least partially electrically conductive housing is connected to a second electric conductor. A switchgear including switching devices.

First claim

The invention claimed is:

1. A knife switch comprising a hinged contact knife, moveable between at least two positions, and a first electric contact element, said contact knife being made of an electrically conductive material and being electrically connectable at a first end to a first electric conductor, said first electric contact element being made of an electrically conductive material, and further comprising an operator device for moving said contact knife between the at least two positions, of which a first position is an open position in which a second free end of the contact knife is disconnected from any electrical contact, and a second position is a first contact position in which the second free end of the contact knife is in electrical contact with the first electric contact element, characterized in that the second free end of the contact knife comprises two knife blades adjacent to each other and that each knife blade is provided with a dynamic electric field control device comprising an electrically conductive element, and that the electrically conductive element has an at least partly spherical shape.

2. The knife switch according to claim 1 , characterized in that each knife blade has an inwards facing electric contact surface facing a corresponding electric contact surface of the other knife blade, said contact surfaces being configured for electric contact with the first electric contact element, and each knife blade having an outwards facing dynamic electric field control device.

3. The knife switch according to claim 1 , characterized in that the first electric contact element is connected to ground.

4. The knife switch according to claim 1 , characterized in that the hinged contact knife comprises a first electrically conductive part connected to the first electric conductor, and a second electrically conductive part articulately connected to the first electrically conductive part and which second electrically conductive part is moveable between said first and second positions, and an optional third position, by means of the operator device.

5. The knife switch according to claim 4 , characterized in that it comprises guiding means for said first electrically conductive part of the contact knife, which guiding means comprises an insulator bar provided with at least one through-hole through which said first electrically conductive part is inserted, and wherein at least one opening of the through-hole is recessed in the insulator bar.

6. The knife switch according to claim 5 , characterized in that the insulator bar is provided with transverse ribs configured to prevent creeping currents.

7. The knife switch according to claim 5 , characterized in that the insulator bar is provided with a support device for supporting the first electric contact element and that the support device is optionally provided with transverse ribs configured to prevent creeping currents.

8. The knife switch according to claim 1 , characterized in that the hinged contact knife is moveable between three positions by means of the operator device, that a third position is a second contact position in which the second free end of the contact knife is in electrical contact with a second electric contact element being made of an electrically conductive material.

9. The knife switch according to claim 8 , characterized in that the second electric contact element is provided with dynamic electric field control devices on externally facing sides thereof.

10. The knife switch according to claim 9 , characterized in that the respective dynamic electric field control device of the second electric contact element comprises an electrically conductive element that has an at least partly rounded shape.

11. The knife switch according to claim 8 , characterized in that electric contact surfaces of the second electric contact element and the contact knife are silver plated.

12. A switching device for electric power distribution switchgear, comprising a two-position switch comprising an at least partly electrically conductive housing,
a three-position switch for connecting the two-position switch to a first electric conductor,
wherein the at least partially electrically conductive housing is connected to a second electric conductor,
wherein the three-position switch is a knife switch according to claim 8 , configured to be able to move between a first position which is an open position in which the second free end of the contact knife is disconnected from any electrical contact, a second position which is a first contact position in which it connects the first electric conductor to the first electric contact element which is connected to ground, and a third position which is a second contact position in which it provides electric connection between the first electric conductor and the two-position switch comprising said second electric contact element, wherein a current path is provided between the first electric conductor and the second electric conductor, via the three-position switch, the two-position switch, and the housing.

13. An electric power distribution switchgear, comprising a sealed gas tight encapsulation inside which is located at least one three-phase module comprising a switching device as defined in claim 12 for each one of said three phases.

14. The electric power distribution switchgear according to claim 13 , wherein the sealed encapsulation is filled with a gas that has a GWP of less than 150.

15. The electric power distribution switchgear according to claim 14 , wherein the sealed encapsulation is filled with a gas that is dry air, or a gas that comprises air mixed with another gas.

Assignees

• Abb Schweiz Ag

Inventors

• Saxegaard Magne
• Talmo Ståle
• Lohne Stanley
• Endre Thor
• Bjortuft Tom-Rune

Classifications

• H01H33/122

  both breaker and sectionaliser being enclosed, e.g. in SF6-filled container · CPC title

• H01H2205/002

  fixed to operating part · CPC title

• H01H33/24

  Means for preventing discharge to non-current-carrying parts, e.g. using corona ring · CPC title

• H01H31/003

  Earthing switches (H01H31/02 - H01H31/26 take precedence; contact made by liquid jet H01H29/32; for substations H02B1/16, H02B5/01; for withdrawable switchgear H02B11/28; for gas-insulated switchgear H02B13/075) · CPC title

• H02B13/0352 Primary

  for three phase switchgear · CPC title