FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
A vacuum interrupter for low end use
INVENTORS
Phase Shantanu, Wakode Deelip, Rajhans Rupesh and Kulkarni Laxmikant, all of Crompton Greaves Limited, S6 Division, D-2 MIDC, Waluj, Aurangabad 431 136, Maharashtra, India, all Indian nationals
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Prabhadevi,
Mumbai 400030, Maharashtra, India, an Indian Company
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to a vacuum interrupter for low end use.
A vacuum interrupter used for low end applications has limited contact stroke of the moving electrode. Generally vacuum interrupters of limited contact stroke are used in vacuum contactors.
PRIOR ART DESCRIPTION
A vacuum interrupter (VI) is a switching device used for interruption of fault current in power supply systems. A vacuum interrupter generally comprises a fixed side subassembly and moving side subassembly vacuum tight brazed at the opposite ends of a vacuum sealed ceramic body which may be single ceramic or double ceramic. The fixed side subassembly generally comprises a fixed side electrode extending into the ceramic body through a fixed side end plate which is brazed to the fixed side electrode and to a fixed side seal cup which in turn is brazed to one end of the ceramic body. A fixed side contact is brazed to the inner end of the fixed side electrode. The moving side subassembly comprises a moving side electrode extending into the ceramic body through a moving side end plate which is brazed to a moving side seal cup which in turn is brazed to the other end of the ceramic body. The moving side subassembly includes a bellows disposed over the moving side electrode with its one end brazed to a collar on the moving side electrode and the other end brazed to the moving side endplate. A


bellow shield is disposed around the bellows with its one end brazed to the said one end of the bellows. A stacking ring is disposed around the moving side electrode and brazed to the said one ends of the bellows and bellow shield. The vacuum interrupter also comprises a centre shield which may be fixed type or floating type. Such a vacuum interrupter comprises a large number of components and a large number of joints. Therefore, cost of the vacuum interrupter is increased and reliability and life of the vacuum interrupter are reduced.
OBJECTS OF THE INVENTION
An object of the invention is to provide a vacuum interrupter for low end use which
comprises reduced number of components and joints and is cost effective.
Another object of the invention is to provide a vacuum interrupter for low end use which has improved reliability and life.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a vacuum interrupter for low end use comprising a fixed side subassembly and a moving side subassembly vacuum tight brazed at the opposite ends of a vacuum sealed ceramic body wherein the moving side subassembly comprises a moving side electrode extending into the vacuum body through


a diaphragm which is vacuum tight brazed to the moving side electrode and to the respective end of the ceramic body, the moving side subassembly further comprising a moving side contact brazed to the inner end of the moving side electrode and a diaphragm cap disposed over the diaphragm and brazed to the moving side electrode.
The following is a detailed description of the invention with reference to the accompanying drawings, in which :
Fig 1 is crosssectional view of a vacuum interrupter for low end use according to an embodiment of the invention; and
Fig 2 is crosssectional view of a vacuum interrupter for low end use according to another embodiment of the invention.
The vacuum interrupter 1 as illustrated in Fig 1 of the accompanying drawings comprises a fixed side subassembly 2 and a moving side subassembly 3. The fixed side subassembly comprises a fixed side electrode 4 extending into a single ceramic body 5 from one end thereof through a fixed side end plate 6. The fixed side end plate is brazed to the fixed side electrode and to a fixed side seal cup 7 which in turn is brazed to the said one end of the ceramic body. 8 is a fixed type centre shield located around the

fixed side electrode and brazed to the fixed side end plate. 9 is a fixed contact brazed to the inner end of the fixed side electrode. The moving side subassembly comprises a moving side electrode 10 extending into the ceramic body from the other end of the ceramic body through a diaphragm 11. The diaphragm is brazed to the moving side electrode and to the other end of the ceramic body. 12 is a cap disposed over the diaphragm and brazed to the moving side electrode. 13 is a moving side contact brazed to the inner end of the moving side electrode. The diaphragm vacuum tight seals the other end of the ceramic body. Due to the flexibility of the diaphragm, the moving side electrode is also able to perform limited stroke during opening and closing of the vacuum interrupter. The vacuum interrupter 14 as illustrated in Fig 2 of the accompanying drawings comprises a double ceramic body formed of ceramic portions 15a and 15b. The centre shield 16 is floating type and is supported between the ceramic portions. The configuration and geometry of the diaphragm and the diaphragm cap can be different. Such variations of the invention are obvious to those skilled in the art and the scope of the invention should be construed and understood accordingly. The invention thus eliminates the bellows, bellow shield and stacking ring and also the moving side end plate and moving side seal cup. The components of the vacuum interrupter of the invention have been reduced. The number of joints of the vacuum interrupter has also been correspondingly reduced. Therefore, the vacuum interrupter of the invention is cost effective and has improved reliability and life.


We claim :
1) A vacuum interrupter for low end use comprising a fixed side subassembly and a moving side subassembly vacuum tight brazed at the opposite ends of a vacuum sealed ceramic body wherein the moving side subassembly comprises a moving side electrode extending into the vacuum body through a diaphragm which is vacuum tight brazed to the moving side electrode and to the respective end of the ceramic body, the moving side subassembly further comprising a moving side contact brazed to the inner end of the moving side electrode and a diaphragm cap disposed over the diaphragm and brazed to the moving side electrode.

Abstract
A vacuum interrupter (1) for low end use comprising a fixed side subassembly (2) and a moving side subassembly (3) vacuum tight brazed at the opposite ends of a vacuum sealed ceramic body (5). The moving side subassembly comprises a moving side electrode (10) extending into the vacuum body through a diaphragm (11) which is vacuum tight brazed to the moving side electrode and to the respective end of the ceramic body. The moving side subassembly further comprises a moving side contact (13) brazed to the inner end of the moving side electrode and a diaphragm cap (12) disposed over the diaphragm and brazed to the moving side electrode (Fig 1).