FIELD OF INVENTION
The present invention relates to providing special mounting arrangement of moisture absorbents in the modules of the gas insulated switchgear equipment to improve absorbance of the moisture present in the SF6 gas so that the properties of gas shall not degrade over a period of time. The invention relates to supporting improvement performance of the GIS.
BACKGROUND & PRIOR ART OF THE INVENTION
Gas insulated switchgear (GIS) is a combination of different modules providing basic requirement of reliable power transfer with minimum possible outage time. An adequate quality has to be ensured during installation of such equipment to fulfill these requirements during the complete GIS life cycle. The gas-insulated switchgear has various modules like disconnector switches, earthing switches, circuit breakers, current transformer, surge arrester, bus bars and bus duct etc. and are located in grounded enclosure/housing filled with an insulating gas, such as Sulfur hexafluoride (SF6) gas. In GIS, moisture is the key factor to limit performance during service. It is possible that moisture may enter the gas insulated module during its assembly at manufacturing works or during reassembly at site or due to poor quality of SF6 gas. Moisture

(particularly in the liquid stage) affects dielectric withstand strength of SF6 gas. In the presence of moisture, decomposed SF6 to form secondary products like hydrofluoric Acid (HF). The produced HF is a highly corrosive substance which can deteriorate the conductors and epoxy insulators surfaces in long run of service. This affects durability of components and in turn modules of GIS.
Hence, to limit moisture, suitable absorbent material i.e., molecular sieves has to be provided in each compartment of GIS. Various mounting arrangements can be made to meet this requirement. These molecular sieves are synthetic crystalline zeolites having a three dimensional sodium alumina silicate frame work having interconnected cavity. Practically, a standard mounting arrangement on each module of GIS is required to keep/replace these material without exposing GIS compartment 100% to environment and site conditions. It is also important that different type of mounting arrangement for each module of GIS may not be economical.
The present invention relates to a highly reliable mounting arrangement for all gas insulated Substation modules like disconnector switch, earthing switches, circuit breakers, current transformer, surge arrester, bus bars, bus ducts etc.
The previous developed designs are mostly considered only for Gas Insulated breaker modules. With reference to Pat. No. US 6,621,030 B2, a sealed vessel of gas-insulated

circuit breaker has a branch pipe attached to a lower part of it. This branch pipe defines a hand hole used for inspection of the circuit breaker, provides a place for installing an absorbent container and forms a foreign matter collecting Space.
In Pat. No. US 2007/0221626 A1, the performance of the breaker is improved by restraining carbon generation, while using an arc extinguishing medium as a mixed gas comprising the element C and having a global warming potential lower than that of SF6 gas. The presence of O2 gas in the mixed gas has the effect of restraining the amount of carbon generated as a result of current interruption. An absorbent having a function of absorbing water, O3 or CO is arranged inside the sealed container.
However, the prior art method does not give any consideration to a fact that the all other modules of the gas-insulated Substation needs the absorbents for moisture disposal. The mounting arrangement is different for different types of modules and most of times it is of man hole type for assembly or replacement of absorbents. Such type of arrangement may lead to exposure of high voltage equipment to site weather conditions and may hamper performance of equipment in long run. Such type of arrangements is not reliable as additional amount of moisture is entering at the time of replacement of moisture absorbent materials. The present patent aims to address the above problems.

OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved system which should limit moisture content inside the modules during service.
It is also an object of the invention to propose a mounting system suitable for any type of module in GIS bay.
It is further an object of the invention to propose an improved mounting arrangement that gives flexibility to utilize the same based on the exact requirement and simplify the system accordingly.
It is another object of the invention to propose an improved mounting arrangement that should be same for all modules of gas insulated switchgear.
It is further an object of the invention to propose an improved mounting arrangement in such a way that replacement of moisture absorbents does not require to open large dimension man holes.
It is yet an object of the invention to propose an improved mounting arrangement in such a way that it has sufficient area to keep moisture absorbents and at the same time does not expose high voltage equipment to weather conditions.

The object of the invention is again to propose an improved system which should not affect the reliability of the modules during service.
The object of the invention also is to propose an improved absorbent mounting system to limit moisture entering the modules of GIS bay during replacement of moisture absorbents.
The object of the invention is also to improve absorbent mounting system which should not modify the electric field distribution between high voltage components and grounded enclosure.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved mounting arrangement for moisture absorbents suitable for modules of all types in a GIS bay. This provides flexibility to utilize the mounting arrangement based on the exact requirement and simplify the system provides.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention is described with the help of Figures 1 to 6, where:
Figure 1: Conventional mounting arrangement in gas insulated breaker.
Figure 2: A sectional view of GIS module.

Figure 3: Mounting arrangement on End cover assembly.
Figure 4: Design and profile of perforated dish.
Figure 5: Assembly sequence of Moisture absorbents replacement.
Figure 6: A Novel Moisture Absorbents Mounting arrangement on various GIS modules.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
The gas insulated substation / switchgear (GIS) comprises of various modules, such as disconnector switch (DS), maintenance earthing switches (MES), fast acting earthing switches (FES), circuit breakers (CB), current transformer (CT), surge arresters (SA), bus bars and bus ducts etc. All GIS modules are comprising of high voltage conductor [01]and sealed in grounded metallic enclosure [02] filled with insulated SF6 gas. In GIS, moisture is the key factor which adversely affect the performance of the equipment. Especially, it has lot of negative impact in the installations of coastal regions, hill areas, snow fall zones etc. For limiting moisture effect, special moisture absorbents [03] known as molecular sieves are used. These elements are synthetic crystalline zeolites having a three dimensional sodium alumina silicate frame work having interconnected

cavity. However, replacement of these elements during service may require special environment to limit the entry of moisture and particles into GIS.
In this invention novel compact mounting arrangement [04] is made suitable for any type of gas insulated switchgear module with limited exposure of high voltage equipment to weather conditions. The moisture absorbents [03] can be located or replaced in end cover [05] without removing the main body [06]. Main body [06] consisting of main dish [07A] and flange [07B]. The main dish [07A] gets modified to pouch [08] and suitable cover/hatch [09] shall be provided for pouch [08]. The dish [07A]is integrated to flange [07B] and shall be mounted on GIS module [10]with appropriate hardware. A profiled perforated dish [11] has been integrated to main dish [07A] to form necessary pouch [08]. The perforated dish [11] provides necessary circulation of SF6 gas. The profile of perforated dish [11] is of spherical type and does not affect the electric field distribution between high voltage conductor and grounded enclosure.
A cover or hatch [09] is used to open / unopen the pouch [08]. To replace the moisture absorbents [03], it is required to open the hatch [09] and keep the elements/moisture absorbents [03] in pouch [08]. When we open the hatch [09], only small openings i.e. about5% area of main dish [07A]is only permitted to enter moisture unlike 100% in conventional mounting arrangements. It is also to be noted that the hatch [09] is only

fraction of area of main dish [07A]. Further, the high voltage equipment/ parts [01]may have very little interaction with environmental conditions. Once we start loading moisture absorbents [03], the holes of perforated dish [11] get closed by these elements and access to the high voltage equipment for the dust particles get reduced. Hence, we can open the outside cover/hatch [09] for easy placement / replacement of the moisture absorbents [03] without disturbing the main body [06]. This will help for easy replacement of the moisture absorbents [03] during maintenance of the gas insulated substation. This type of concept can be extended to any insulated type of switchgear.
Conventionally, moisture absorbents [03] are provided in circuit breaker module. However, currently it is important to keep moisture absorbents [03] in all the GIS modules as weather conditions decide the performance of equipment in large scale. In all the modules of GIS, the same arrangement can be repeated by maintaining modularity. Sometimes, in smaller GIS sections / lower voltage GIS, similar novel mounting arrangement can be developed with reduced dimensions of pouch as moisture absorbents requirement gets reduced with decrease in GIS section dimensions. Hence, the novel design developed can accommodate any quantity of moisture absorbents [03] based on the requirements.

WE CLAIM
1) A modular mounting arrangement (04) of moisture absorbents (03), suitable to be mounted on the main body (06) of end cover (05) for all the modules of gas insulated substation (GIS) bay comprising, flange (07B), main dish (07A), perforated dish (11), hatch/cover (09), pouch (08) to hold the moisture absorbents (03), which are integrated in to the main dish (07A), wherein, the area of opening of the pouch being 5% of conventional manhole dimensions.
2) The arrangement as claimed in claim 1, wherein the moisture absorbents (03) are housed in pouch (08) made of perforated dish (11), having an area of a fraction of the main dish (07A)
3) The arrangement as claimed in the preceding claims, wherein entry of moisture is limited at the time of replacement of moisture absorbents, characterized by its lower exposed area, 5% of conventional openings.
4) The arrangement as claimed in the preceding claims, wherein the mounting arrangement (04), in particular, spherical profiled perforated dish (11), made up of low weight aluminium casting.