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 device to provide a displacement to insulating rod of a gas circuit breaker in the vertical axis by a known quantity.
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Himanshu Chandrakant Joshi, Vishal Vijay Bagade and Satheesan, all of Crompton Greaves Limited, Technology Cell (S3), A-3, MIDC, Ambad, Nasik, Maharashtra, India, all Indian Nationals.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The invention relates to a device to provide a displacement to insulating rod assembly of a gas circuit breaker in the vertical axis by a known quantity. The insulating rod assembly is connected to the moving contacts of a gas circuit breaker. By providing a known displacement to the insulating rod assembly the device can determine if the contacts in a gas circuit breaker is properly aligned.
BACKGROUND OF THE INVENTION
A medium voltage gas circuit breaker as known comprises of stationary and moving contact assemblies. The moving contact assembly is enclosed in a housing mounted vertically on a control box housing an insulating rod assembly for moving the moving contacts of the circuit breaker. The alignment of the stationary and moving contacts need to be checked during the manufacturing and assembling process of a gas circuit breaker to ensure that the closing and opening of the contacts happen correctly and functions as desired when installed on field. The airgrtment check requires to be done early in the manufacturing and assembling process to avoid complicated re-alignment and rework of re-assembling the gas circuit breaker later.
The functioning of modern medium-voltage puffer type SF6 gas circuit breakers functioning is based on the switching of stationary and moving contacts. The stationary contact is formed by a stationary arc contact concentrically placed within a stationary main contact; the moving contact is formed by a moving arc contact and a moving main contact.

For the correct functioning of the gas circuit breaker during a 'close operation' of a gas circuit breaker, the stationary main contact and moving main contact are in contact with each other with the corresponding arcing contacts are concentrically enclosed within a spaced radial distance of each other. In the 'close operation' the main contacts carry the normal load current without causing excessive temperature rise. During a 'open operation' of a gas circuit breaker, the stationary main contact and moving main contact withdraw, following which the corresponding arcing contacts withdraw causing an electric arc between them which is subsequently quenched.
Ideally, the moving arcing contact should not touch to the stationary arc contact by design. However due to improper alignment in the contact assembly there is a possibility of the arcing contacts touching each other resulting in a 'mismatch'. As known to one skilled in the art, such 'mismatch' used to get detected only after an elaborate timing measurement test being performed for every assembled gas circuit breaker. The entire pole unit assembly (the stationary contact, moving contact and the insulating rod assembly) requires being re-worked and re-done resulting in an expensive process and several man hours lost. Such 'mismatch' also degrades the product quality. To overcome the problems as described there is a need for a device which can facilitate the checking of the contact alignment of the main contacts and corresponding arcing contacts such that a 'mismatch' is avoided.
OBJECTS OF THE INVENTION
An object of the invention is to provide a device to provide a displacement to insulating rod of a gas circuit breaker in the vertical axis by a known quantity.

DETAILED DESCRIPTION OF THE INVENTION
A device to provide a vertical displacement of an insulating rod assembly of a gas circuit breaker, the device comprising of a worm gear and worm shaft along with a handle that essentially comprises a drive means to provide a rotary motion. The rotary motion is converted in to a vertical motion by the action of a pivoted joint that is connected to the insulating rod assembly. The magnitude of vertical displacement provided to the insulating rod assembly can be measured by a measuring scale provided on the device. The magnitude of angular displacement proportional to the vertical displacement can also be measured using a protractor arrangement on the device. If arcing contacts touch occurs at a vertical displacement as measured which is less than specified value, the pole unit assembly needs to be reworked.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 is a back isometric view of the device according to the invention.
Fig 2 is front isometric view of a device according to the invention.
Fig 3 is a front view of the device according to the invention.
Fig 4 is a back view of the device according to the invention.
Fig 5 is representative schematic view of a gas circuit breaker with its pole unit assembly and
the insulating rod connected to the link of the device to provide displacement on the vertical
axis to engage and disengage the moving contact with the stationary contact.

Fig 1 is a back isometric view of the device according to the invention and is shown comprising the driving means for the insulating rod 8 (shown in part)which in turn drives contacts 18(shown in fig 5). The device is shown comprising of a handle 1 securely attached to a worm shaft 3 supported on support blocks 4. A worm gear 2 is in arrangement with worm shaft 3 and transmits the rotary motion of handle 1 to a rotary motion of the worm gear 2. Worm gear 2 is mounted on a central rod 5 that extends through a base plate 9. A shaft 6 is connected to the central rod by means of a socket 17. A link 7 is firmly secured to the shaft 6, and the insulating rod assembly 8 is pivotally held to the link 7. Moving main contacts 18 attached to insulating rod assembly. A rotary motion of the handle 1 is transmitted through the worm gear and shaft arrangement to the central rod 5 and translates in to a movement on the vertical axis of the insulating rod 8 which is pivotally held from a link 7. Adjustable spacers 10 are used to provide the required alignment to the device with the frame on which the gas circuit breaker is erected.
Fig 2 is a front isometric view of the device according to the invention and is shown comprising of a bevel protractor 11 and a pointer 13 that measures the angular displacement. A control rod 15 is connected to the central rod 5 by means of a connect plate 16. The connect plate 16 is firmly supported at the control rod 15 and pivotally at the control rod in a oblong slot provided in the connect plate 16. The anguliir motion of the central rod 5, translates in to a vertical motion of control rod 15. A user can measure the vertical displacement by measuring the initial and final readings on the measuring scale 12.
Figure 3 and Figure 4 are the front and back views of the device and can be understood in conjunction with the descriptions of Figure 2 and Figure 1 respectively.

Fig 5 is representative schematic view of a gas circuit breaker 20 with its pole unit assembly and insulating rod 8 connected to the link 7 of the device to provide displacement on the vertical axis to engage and disengage the moving contacts 18 with the stationary contacts 19. The rotary action of the link 7 as illustrated at two instances of time is super-imposed to represent the manner in which a vertical displacement is provided to the insulating rod 8 which further is connected to the moving contacts 18, which is pivotally supported by link 7. The stationary main contact 19 is hollow cylinder in shape in which moving arc contact gets penetrated. Moving main contact 18 is connected to insulating rod 8 which is connected to link 7. Depending on the vertical displacement of the insulating rod the moving main contact (and therefore the moving arcing contact) open or close the gas circuit breaker.
For a pre-determined angular displacement and proportional vertical displacement a 'close operation' is expected. The insulating rod 18 is effected a pre-determined vertical displacement and simultaneously a connectivity test is performed. The connectivity test is performed between the metallic portions of the gas circuit breaker 21 and 22 each of the being connected to the stationary contact and moving contact respectively. A positive connectivity test between the moving arcing contact and the stationary arcing contact indicates the occurrence of a 'mismatch' and consequently the pole unit assembly which includes the stationary and moving contacts and their relative movement with each other needs to be re-worked to ensure a correct 'close operation'.
The device as described in figures 1-5, essentially provides a vertical displacement of the insulating rod of a gas circuit breaker by a known quantity. Although the invention has been described with reference to a specific embodiment, this description is not meant to be

construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the invention as defined.

We claim:
1. A device to provide a vertical displacement of an insulating rod assembly of a gas circuit
breaker, the device comprising of:
a drive means for providing a rotary motion ; and
a measuring means to measure an angular and vertical displacement effected by the rotary
motion;
a central rod extending on both sides of a base plate through a slot provided in the base plate,
wherein the central rod transmits the rotary motion delivered by the drive means to the
measuring means; and
a pivoted link connecting the insulating rod assembly and the drive means by a shaft and
converting the rotary motion as provided by the drive means to a vertical up-down motion of
the insulating rod assembly ; and
a set of adjustable spacers providing an alignment of the base plate against a frame on which
the gas circuit breaker is mounted.
2. A device as claimed in claim 1, wherein the drive means comprises of:
a worm gear mounted on a worm shaft, the worm gear being disposed through the central rod and the worm shaft being supported on two support blocks on the base plate, wherein the rotation of the worm shaft turns the worm gear and the central rod; and wherein, the worm shaft is rotatable along its axis with a handle provided at one end of the worm shaft
3. The device of claim 1, wherein the measuring means comprises of:

a protractor being mounted on the base plate and a first pointer being mounted on the central rod, the first pointer indicating an angular displacement on the bevel protractor, wherein the angular displacement is proportional to the rotary motion provided by the drive means; and a connect rod pivotally held to the central rod by a connect plate, the connect rod supporting a second pointer, the second pointer being provided a linear motion indicating the vertical displacement on a measuring scale provided thereof.