FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
A testing assembly to estimate (by observation and calculation), the diffusion time constant of moisture from cellulosic insulation into oil
APPLICANT (S)
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S)
Chaudhari Sushil Ekanath, Umashankar Babuparamashiva and Chavan Vinila Sandeep of Crompton Greaves Ltd, Condition Monitoring & Diagnostic Research Centre, CG Global R&D Centre, Kanjur (E), Mumbai 400042, Maharashtra, India, Indian National
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 the field of mechanical assemblies.
Particularly, this invention relates to a testing assembly to estimate (by observation and calculation), the diffusion time constant of moisture from cellulosic insulation into oil.
BACKGROUND OF THE INVENTION:
Transformers are an integral part of power systems in order to step up voltage, step down voltage and the like functions. Transformer is a device which transfers electrical energy from one circuit to another through inductively coupled conductors i.e. through transformer's coils. The transformer coils are immersed in oil which acts as an insulator and dielectric medium.
Excessive moisture in transformers causes problem. The solid insulation in the transformers is attacked by water, as cellulosic material is hygroscopic and attracts moisture. In transformers, the oil acts as a transfer medium and its ability to dissolve water increases with temperature. Temperature leads to molecular chain scission of cellulosic insulation and forms byproducts like carbon oxides, water and furanic compounds.
In the diffusion process of water from cellulosic insulation to oil, the coefficient of diffusion depends on the structure (pore size) of the cellulose, temperature and water content. Since the water solubility in oil and the adsorption capacity of cellulose materials are temperature dependent, a change of temperature results into moisture diffusion inside materials and between cellulose and oil. With increasing temperature, the water solubility in oil increases and the water adsorption capacity

of cellulose decreases. Thus, the equilibrium process forces water molecules to migrate from cellulose to oil. At decreasing temperatures, the cellulose materials again take up water molecules from the oil.
When the oil temperature increases, a temporary reduction in the relative water saturation occurs until moisture is driven from the conductor-wrapped insulation, which is heated first. This drives the moisture from the conductor-wrapped cellulosic insulation to the major or bulk insulation. As the bulk insulation heats up, some of the collected surface moisture will begin to migrate to the oil. The moisture content in pressboard will develop a water vapour pressure distribution such that the highest value is at the surface where it is warmer. This is because the diffusion time constants for significant moisture movement to the inner bulk material are long. When these bulk insulation surfaces in the cooler regions are warmed, their relatively higher surface potentials will contribute significantly to the water content of the bulk oil. As load changes, the temperature of the oil and solid insulation will vary forcing moisture to migrate to and from surfaces.
The effect of ageing of cellulosic insulation due to moisture causes:
1. accelerated rate of aging for cellulosic materials such as kraft paper and pressboard;
2. reduction of dielectric strength with increasing the relative saturation of moisture in oil;
3. reduction of the dielectric strength of paper and pressboard materials;
4. risk of bubble evolution at high temperatures
Understanding of the processes of water ingress, equilibration and migration, the dangerous effects of excessive water, and effective diagnostic methods, are necessary for effective and efficient "life management".

PRIOR ART:
US2011043230 relates to moisture monitoring device and method. This patent application discloses a moisture monitoring device that measures the dielectric constant of a material to provide an indication of the moisture content of a material.
CN101726514 relates to Oil-immersed type transformer solid insulation moisture content assessment method based on return voltage.
The invention discloses oil-immersed type transformer solid insulation moisture content assessment method based on return voltage. It judges the moisture content according to a main time constant of the polarized spectrum curve.
KR20070071692 relates to measuring apparatus for moisture change. This patent application discloses a moisture change measuring device is provided to measure the moisture amount change, rapid drying capability, moisture diffusion capability and water-proof capability according to the time of a surface layer and a rear side layer.
WO2009156296 relates to test body, test arrangement, method for manufacturing of a test body, and method for determining a moisture content of the insulation of a power transformer during drying thereof.
This patent application discloses test body for use in determining moisture content in a laminated insulation of a power transformer by means of measuring a dielectric frequency response of the test body is provided. It comprises of electrodes embedded in a laminated structure.

WO2008026997 relates to a method and a device for determining the moisture content in a part of the insulation of a power transformer during drying thereof. The patent application discloses a method of determining the moisture content in a part of the insulation of a power transformer.
CA2121775 relates to a method and device for measuring moisture content. This patent application discloses a device for measuring the moisture content of an absorbent material, for example the paper insulation in an electrical transformer, uses a back scattered radiation technique to determine the absorption of light at specific wavelengths.
However, there is no assembly to assess the entire insulation oil and its characteristics, as a whole, in one single testing assembly.
OBJECTS OF THE INVENTION:
An object of the invention is to provide an assembly for insulation oil.
Another object of the invention is to provide an assembly for estimating diffusion time constant of moisture from cellulosic insulation into oil.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a testing assembly to estimate (by observation and calculation), the diffusion time constant of moisture from cellulosic insulation into oil, said assembly comprises:
a. a housing adapted to house said oil;
b. at least two sensors, in said housing, adapted to monitor moisture as a
function of temperature;

c. glass window, on said housing, laterally located, adapted to monitor the
movement of oil and condition of solid insulation under elevated
temperature;
d. perforated compartment, in said housing, for storing cellulosic insulation for
testing diffusion of moisture from solid to liquid; and
e. lid to cover said housing which will be filled with oil and cellulosic
insulation, said lid fitted with heater and circulator for heating and
homogenizing the insulating oil.
Typically, said assembly is a fabricated stainless steel assembly.
Typically, said assembly is a double walled assembly.
Typically, said sensors are temperature and moisture sensors.
Typically, said assembly consists of two ball valves; one at operative top and another at operative bottom, said top valve serving the function of applying vacuum to said assembly to fill oil inside said assembly and said bottom valve adapted to intake oil from an oil reservoir.
Typically, an oil impregnated paper system is heated with the heater which is mounted atop of the lid.
Typically, said assembly includes a heater with in-built pump to homogenize the oil and to provide better thermal conductivity of said insulating oil inside the said assembly.

Typically, the oil inside the assembly is heated up using a heater cum circulator, which serves both purposes of heating and homogenizing the oil. The homogenization of oil is done by the in-built pump of the heater itself.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in
which:
Figure 1a illustrates a top view of the assembly; Figure lb illustrates a front view of the assembly; and Figure lc illustrates a side view of the assembly.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided a testing assembly for testing insulation oil.
Figure 1a illustrates a top view of the assembly (100). Figure lb illustrates a front view of the assembly (100). Figure lc illustrates a side view of the assembly (100).
To estimate (by observation and calculation), the diffusion time constant of moisture from cellulosic insulation into oil, a stainless steel assembly was designed and fabricated.

In accordance with an embodiment of this invention, the assembly consists of at least two sensors (12) adapted to monitor the moisture as a function of temperature.
In accordance with another embodiment of this invention, the assembly includes a glass window (22) to monitor the movement of oil and condition of solid insulation under elevated temperature.
In accordance with yet another embodiment of this invention, the assembly consists of a perforated compartment (16) for cellulosic insulation.
In accordance with still another embodiment of this invention, the assembly consists of a lid (18) to cover the housing which will be filled with oil and cellulosic insulation.
The assembly is double walled to reduce heat loss. Also, the assembly consists of two ball valves, one at top and another at bottom. The top valve serves the function of applying vacuum to the assembly to fill the oil inside the assembly and bottom valve is adapted to intake oil from an oil reservoir.
Prior to testing, the assembly is fitted with a lid accompanying with a circulator and a glass window. After fitting the lid, the assembly is tested for leakage. The cellulosic insulation is kept in the perforated compartment inside the assembly for diffusion of moisture from solid to liquid. The oil from reservoir is pumped in the assembly by applying vacuum at the operative top end of the assembly. When the external circulator starts to circulate the oil for effective heat transfer. Also, the

sensors are activated to read and monitor the moisture with temperature. The oil is heated to a pre-defined respective temperature for diffusion of moisture.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A testing assembly to estimate (by observation and calculation), the diffusion
time constant of moisture from cellulosic insulation into oil, said assembly
comprising:
a. a housing adapted to house said oil;
b. at least two sensors, in said housing, adapted to monitor moisture as a
function of temperature;
c. glass window, on said housing, laterally located, adapted to monitor the
movement of oil and condition of solid insulation under elevated
temperature;
d. perforated compartment, in said housing, for storing cellulosic insulation
for testing diffusion of moisture from solid to liquid; and
e. lid to cover said housing which will be filled with oil and cellulosic
insulation, said lid fitted with heater and circulator for heating and
homogenizing the insulating oil.
2. A testing assembly as claimed in claim 1 wherein, said assembly is a fabricated stainless steel assembly.
3. A testing assembly as claimed in claim 1 wherein, said assembly is a double walled assembly.
4. A testing assembly as claimed in claim 1 wherein, said sensors are moisture and temperature sensors.

5. A testing assembly as claimed in claim 1 wherein, said assembly consists of two ball valves; one at operative top and another at operative bottom, said top valve serving the function of applying vacuum to said assembly to fill oil inside said assembly and said bottom valve adapted to intake oil from an oil reservoir.
6. A testing assembly as claimed in claim 1 wherein, an oil impregnated paper system is heated with the heater which is mounted atop of the lid.
7. A testing assembly as claimed in claim 1 wherein, said assembly includes a heater with in-built pump to homogenize the oil and to provide better thermal conductivity of said insulating oil inside the said assembly.
8. A testing assembly as claimed in claim 1 wherein, said assembly includes an inlet port and an outlet port for said oil.