# US 4,393,286 A · Vacuum circuit breakers

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,393,286 A
- Document ID: US4393286A
- Status: Granted
- Kind: A
- Application number: 06/066,772
- Filed: 1979-08-15
- Granted: 1983-07-12
- Earliest claimed: 1978-08-24
- Assignees: Tokyo Shibaura Denki Kabushiki Kaisha
- Inventors: Kunihiko Takagi
- Web page: https://patentgrep.com/patent/US4393286A

## CPC

- H01H 33/66207: {Specific housing details, e.g. sealing, soldering or brazing}
- H01H 2033/6623: {Details relating to the encasing or the outside layers of the vacuum switch housings}
- Y10S 174/08: Shrinkable tubes
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A vacuum circuit breaker having a vacuum bulb comprises a coating of a greasy compound of a water repellent material provided on the outer surface of the bulb, and an insulating tube of a water repellent and heat shrinkable material provided on the coating of the greasy compound.

## Claims

### Claim 1

In a vacuum circuit breaker having a vacuum bulb including an insulating member for containing a movable contact and a stationary contact, the improvement which comprises:
a coating of a greasy compound of a water repellent material provided on the outer surface of said insulating member;
an insulating tube of a water repellent and heat shrinkable material provided on said coating of the greasy compound; and
insulating rings between said coating of the greasy compound and said insulating tube.

### Claim 2 (depends on 1)

A vacuum circuit breaker as claimed in claim 1, further comprising a conductive portion, wherein said coating of the greasy compound is also provided on the outer surface of said conductive portion.

### Claim 3 (depends on 1)

A vacuum circuit breaker as claimed in claim 1, wherein said vacuum bulb comprises a cylindrical insulating member and a pair of annular conductive members having their respective edge portions connected to both ends of said cylindrical insulating member, and said coating of the greasy compound is provided to cover said edge portions of said annular conductive members.