Explosively-actuated, multi-gap high voltage switch

• US 4,490,707 A
• Filed: 10/06/1983
• Issued: 12/25/1984
• Est. Priority Date: 08/18/1980
• Status: Expired due to Fees

• Current Assignee: S&C Electric Company
• Original Assignee: S&C Electric Company
• Inventors: O'Leary, Raymond P.
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US06/539,396
• Time in Patent Office: 446 Days
• Field of Search: 337/30, 337/115, 337/402, 337/143, 337/156, 337/401, 337/4, 337/6, 337/158-162, 337/412, 337/148, 337/251, 337/275, 337/282, 200/82 B, 200/150 M, 200/61.08
• US Class Current: 337/6
• CPC Class Codes: H01H 33/14 Multiple main contacts for the purpose of dividing the current through, or potential drop along, the arc
• CPC Class Codes: H01H 39/006 Opening by severing a conductor
• CPC Class Codes: H01H 9/106 fuse and switch being connected in parallel

Abstract

A high-speed switch usable at high voltage includes a pair of contacts movable apart along a fixed line. When the contacts are normally interconnected, at least one of them contributes to the definition of an enclosed chamber. Pressurization of the chamber by the ignition of a power cartridge therein rapidly drives the contacts apart, forming a first gap between them. The first gap is electrically insulated and is shielded from the ignition products of the cartridge. Any arc forming in the first gap is constricted and subjected to arc-extinguishing gas. When the contacts are interconnected, a first one of them is electrically connected to a terminal. After the contacts move apart, a second gap forms between the first contact and the terminal. The second gap is electrically insulated and is shielded from the ignition products of the cartridge. A fuse may be connected in shunt with the contacts and the insulated gaps. Preferably, the shunt connection is made after the first gap is formed, but before the second gap is formed. This permits the first gap to effect commutation of current from the switch to the fuse and the second gap to be formed after the communtation. The second gap thus experiences no or only limited arcing and remains essentially uncontaminated so that recommutation of current from the fuse to the switch is prevented.

Claims

1. An electrical switch for opening a first current path in which the switch is included, comprising:

a pair of normally electrically interconnected contacts which are separable along a first line of direction to both break the electrical interconnection and to form a first gap therebetween;

first means for inserting a solid electrical insulator between the contacts as they separate to electrically insulate the first gap;

a terminal in the first path;

second means for electrically connecting one contact to the terminal when the contacts are interconnected, a second gap forming between the one contact and the terminal as the contacts separate at a predetermined time after the formation of the first gap;

third means for inserting a solid electrical insulator between the one contact and the terminal as the contacts separate to electrically insulate the second gap;

fourth means for defining with the first means a chamber, pressurization of the chamber separating the contacts;

ignitable means in the chamber, ignition of which pressurizes the chamber;

a second current path; and

fifth means for connecting the second path in shunt with the first path after the first gap is formed.

2. The device of claim 1, wherein the second path includes a fuse.

3. The device of claim 1, wherein the one contact is movable away from the other contact and toward the terminal as the contacts separate, and the first means comprises

(a) a first electrically insulative member carried by and movable with the one contact so as to be interposed between the contacts as they separate, and

(b) a first electrically insulative sleeve through which the one contact is movable and the first insulative member is conformally movable as the contacts separate;

the third means comprises

(a) a second electrically insulative member carried by and movable with the one contact so as to be interposed between the one contact and the terminal as the contacts separate,

(b) a third electrically insulative member carried by the terminal so as to be interposed between the one contact and the terminal as the contacts separate; and

(c) the second and third insulative members conformally telescoping as the contacts separate; and

the fifth means comprises

(a) sixth means for electrically connecting one end of the second path to the other contact, the other end of the second path being normally electrically unconnected to the terminal, and

(b) seventh means responsive to movement of the one contact for electrically connecting the other end of the second path to the terminal after the contacts have separated a predetermined amount.

4. The device of claim 3, wherein:

the sixth means further comprises

(a) a first electrically conductive member connected to the terminal, and

(b) a second electrically conductive member connected to the other end of the second path and separated from the first conductive member; and

the seventh means comprises

a third electrically conductive member insulated from and movable with the one contact, the third conductive member being separated from the first and second conductive members when the contacts are electrically interconnected and simultaneously contacting the first and second conductive members after the contacts have separated a predetermined amount.

5. The device of claim 4, wherein:

the other contact is stationary;

the terminal is stationary;

the one contact includes a conductive tube movable through the first sleeve;

a second insulative sleeve covers the exterior of the tube and carries the third electrically conductive member;

the second insulative member covers a first portion of the interior of the tube, a second portion of the interior of the tube being uninsulated;

the terminal includes a conductive rod telescoped into the tube;

the third insulative member covers a first portion of the extension of the rod, a second portion of the exterior of the rod being uninsulated;

the first and second conductive members are carried by the first sleeve; and

the second portion of the interior of the tube electrically engages the second portion of the exterior of the rod when the contacts are electrically interconnected;

the second portion of the exterior of the rod is first in sliding electrical engagement with the second portion of the interior of the tube and then in sliding engagement with the second insulative member as the contacts separate; and

the second portion of the interior of the tube is first in sliding electrical engagement with the second portion of the exterior of the rod and then in sliding engagement with the third insulative member as the contacts separate.

6. The device of claim 5, wherein the dimensions, relative positions and configurations of the tube, the rod, the first, second and third insulative members, the second sleeve and the first, second and third conductive members are selected so that the formation of the first and second gaps and the connection of the other end of the second path to the terminal occur in a predetermined sequence.

7. The device of claim 6, wherein the other end of the second path is connected to the terminal after formation of the first gap and before formation of the second gap.

8. The device of claim 3, 4, 6 or 7, wherein the second path includes a fuse.

10. The switch of claim 9 or 1, wherein said fifth means connects the second path in shunt with the first path before the second gap is formed.

11. The switch of claim 9 or 1, wherein said fifth means connects the second path in shunt with the frst path as the second gap is formed.

13. The device of claim 1, wherein the second path includes a fuse.

14. The device of claim 13, wherein the isolating, insulating and constricting functions of the first piston means sufficiently elevate the voltage of any arc formed between the contacts so that current in the first path transfers to the second path when the third means electrically connects the second path in shunt with the first path and so that when the second gap forms no arcing between the first contact and the terminal occurs, the second gap being thus initially uncontaminated, the insulating function of the second means prevents both formation of any arc in the second gap and retransfer of the current from the second path to the first path as the fuse operates.

9. An electrical switch for opening a first current path in which the switch is included, comprising:

a terminal in the first path;

a pair of normally electrically interconnected contacts which are separable along a first line of direction to both break the electrical interconnection and to form a first gap therebetween, the one contact being movable away from the other contact and toward the terminal as the contacts separate;

first means for inserting a solid electrical insulator between the contacts as they separate to electrically insulate the first gap, said first means including a first electrically insulative member carried by and movable with the one contact so as to be interposed between the contacts as they separate, and an electrically insulative sleeve through which the one contact is movable and the first insulative member is conformally movable as the contacts separate;

second means for electrically connecting one contact to the terminal when the contacts are interconnected, a second gap forming between the one contact and the terminal as the contacts separate at a predetermined time after the formation of the first gap;

third means for inserting a solid electrical insulator between the one contact and the terminal as the contacts separate to electrically insulate the second galp, said third means including a second electrically insulative member carried by and movable with the one contact so as to be interposed between the one contact and the terminal as the contacts separate and a third electrically insulative member carried by the terminal so as to be interposed between the one contact and the terminal as the contacts separate, wherein the second and third insulative members conformally telescope as the contacts separate;

fourth means for defining with the first means a chamber, pressurization of the chamber separating the contacts;

ignitable means in the chamber, ignition of which pressurizes the chamber;

a second current path; and

fifth means for connecting the second path in shunt with the first path after the first gap is formed.

12. An electrical switch for opening a first current path in which the switch and a terminal are included, comprising:

a second current path;

first and second normally electrically interconnected contacts for carrying current in the first current path, the first contact being relatively movable along a fixed line of direction away from the second contact to break the electrical interconnection therebetween;

first piston means on the first contact for

(a) defining an enclosed chamber with the second contact when the contacts are interconnected;

(b) interpositioning between the contacts to isolate the first contact from the chamber and electrically insulating the contacts from each other as and after the first contact moves away from the second contact, and wherein the first piston means forms an insulative first gap between the contacts as and after the first contact moves away from the second contact;

(c) constricting any arc formed between the contacts after the first contact moves away from the second contact;

second means for

(a) electrically connecting the first contact to the terminal when the contacts are electrically interconnected, and

(b) inserting a solid electrical insulator between the one contact and the terminal to electrically insulate the first contact from the terminal after the first contact moves away from the second contact, wherein the second means forms an insulated second gap between the first contact and the terminal at a predetermined time after the formation of the first gap;

third means for electrically connecting the second path in shunt with the first path after the first gap is formed and before the second gap is formed; and

ignitable means in the chamber for pressurizing the chamber upon ignition thereof to rapidly drive the first contact away from the second contact.

15. A high-voltage fuse having a high continuous current rating, comprising:

a first current path having a high continuous current-carrying capacity;

a second current path;

a fuse in the second path;

first means for opening a first insulated gap in the first path, an arc forming in the first gap;

second means for connecting the second path in shunt with the first path as the voltage of the arc in the first gap elevates to transfer current from the first path to the second path; and

third means for opening a second insulated gap in the first path after current therein transfers to the second path so that the second gap is uncontaminated and so that as the arc voltage of the fuse elevates, retransfer of the current to the first path is prevented by the presence of the first gap and the second uncontaminated gap in the first path.

16. The fuse of claim 15, which is a current-limiting fuse having low let-through, wherein the fuse is a current-limiting fuse.

17. The fuse of claim 15 or 16, wherein the second path surrounds the first path, and which further comprises

an insulative housing enclosing both paths.

18. The fuse of claim 20 or 16, wherein

the first means comprises

a pair of normally electrically interconnected contacts separable along a fixed line of direction to form the first gap,

means for electrically insulating the first gap as the contacts separate, and

ignitable means, ignition of which separates the contacts;

and

the third means comprises

a terminal electrically connected to one contact when the contacts are interconnected, the second gap forming between the terminal and the one contact as the contacts separate, and

means for electrically insulating the second gap as the contacts separate.