Title of Invention

AN EMBEDDED DEVICE AND A METHOD FOR DIRECT DETERMINATION OF DEGREE OF POLYMERIZATION OF CELLULOSE BASED PAPER INSULATION OF A TRANSFORMER

Abstract The present invention relates to an embedded device and a method for estimation of degree of polymerization (DP) of cellulose based paper insulation of transformer comprising means for collecting cut paper samples from the leading ends of a transformer, means for conveying said collected papers through the embedded device, comprising five set of rollers (1 to 5) for squeezing of oil from the test insulation paper, cleaning the paper with a solvent, drying the sample paper with heating means (H) controlled with a electronic circuit, and to drag out the paper out of the machine respectively. In between fourth and fifth set of rollers are provided a shredding means (SM) with punches to cut the paper into small circular pieces and a paper chip chute conveyor ( c) for transporting the small pieces of paper to a digital moisture balance (W) to weigh the initial and dried out weight and moisture content of the paper samples. The preweighed and dried paper sample pieces are dissolved in a glass flask (F1 & F2) containing predetermined amount of DM water and CED by shaking in a shaker assembly. The efflux time for blank and sample solution is recorded via sensor in a builtin digital analog computer by noting 1st and 2nd signal for corresponding 1st and 2nd mark for the said blank and sample solution, to give a measure of viscosity of the solution, DP of the sample paper through a software using Martin's curves, all the operations of the rollers, shredding means and chute conveyor are controlled through an integrated PC with controller circuit via a RS 232 port.
Full Text FIELD OF THE INVENTION
This invention relates to an automated machine for estimation of degree of
polymerization (DP) of cellulose based paper insulation transformer. More
particularly the proposed invention relates to enhance health and residual life of
a transformer by estimating furfural content of transformer oil by determination
of DP of cellulose based insulating papers used in a transformer.
BACKGROUND OF THE INVENTION
In transformer oil is used as a cooling medium to remove the heat caused by
core losses and copper losses. Transformer oil is a high grade insulating oil which
must be kept free of any foreign material and moisture and this liquid is a
dielectric which serves effectively as a cooling and insulating agent.
In transformer the insulation of winding is made up of cellulose paper. Cellulose
insulation deteriorates with age and also due to heating, short term and long
term over loads, number and intensity of short circuits, incidence of lightening
surges, internal faults and electrical breakdown resulting in production of furfural
derivatives which dissolve in oil. In practice the insulating qualities of the oil are
checked at periodic intervals. Chemical analysis of transformer oil indicates
evidence of changes taking place in the winding insulation during normal
operations. Residual life and effective performance of a transformer are being
assessed by estimation of furfural content in oil and by estimation of degree of

polymerization (DP). The presently employed direct method of estimation of
furfural in oil may reflect critically the conditions of a transformer but this
method is not applicable where the oil is partially or totally replaced. At present
estimations of furfural derivatives and DP in the oil are done at the Lab after
transporting the samples and using HPLC equipment (IEC 61198) and IEC
600450 procedures respectively. These procedures involve cumbersome
measurements causing delay in life estimation and involve inflicting human error
In the old art residual life of transformer is assessed by estimating furfural
content in oil by HPLC method and DP of paper by standard viscometric method.
Subsequently, the methodology was extended to field applications by collecting
data from a number of transformers and a data bank has been created. Using
the simulated lab experimental data and from the data bank created, a
relationship between DP and furfural was developed. Another relationship
between furfural and life of transformer has been developed. These two
relationships are converted into a software through which it is possible to know
theoretical furfural and DP value expected from name plate / service age of
transformer.
The steps involved in present practice of DP estimation of cellulose paper, in
chronological order are:
1. removal of oil from cellulose insulation paper by treatment with solvent
mixtures by soxhlet apparatus,

2. removal of solvent from paper by manuai pressing and squeezing,
3. cutting the celiuiose paper manually into small pieces using scissors,,
4. drying the paper in oven for moisture estimation,
5. weighing the paper on analytical balance,
6. transferring 22.5mi H2O & 22.5ml copper ethylene diamine (CED) (total 45
ml) into a conical flask manually,
7. dissolving paper in 45 mi copper ethylene diamine in water by manual
shaking or using fiask shaker,
8. visual testing of solution for total dissolution,
9. transferring approximately 10 ml of solution manually into glass
viscometer,
10. determining the time of flow of measuring of solution between two marks
on viscometer manually using stop watch and
11. manual calculation of DP by computing Intrinsic Viscosity and Specific
Viscosity from equated relationship between DP and furfural and between
furfural and life of transformer via soft ware developed for these relationships.

PRIOR ART REFERENCE
In assessment of DP of cellulose insulating materials of transformer there are
some prior art references in published book and patent literatures.
In TV Oomen, LN Arnold 'Cellulose Insulation Materials Evaluated by Degree of
Polymerisation Measurements". IEEE 1981^ p.257-261, TV Oomen of
Westinghouse evaluated cellulose insulating materials by determining the degree
of polymerization (DP) and diagnosed the hotspots in the paper samples
collected from different coiis of transformers. This technique is very useful in
assessing the life of the transformer. But, availability of paper samples from
windings is difficult as it needs opening up of transformer.
In DH Shroff, AW Stannett "Review of paper Ageing in Power Transformers".
IEEE Proceedings, Vol.l2,p.312-319, Shroff et al suggested to establish the
furfural content in transformer oil and DP of cellulose paper. When the cellulose
paper degrades, it gives products like 2-furfurai, 5-hydroxy 2-methyl furfural, 2-
furolic acid, 2-furfural alcohol, 2-acetyl fural etc. These degradation products go
into transformer oil. Among the products, 2-furfurai is highly significant and
indicates the level of decomposition of insulating paper. By monitoring the level
of furfural content, and DP of the paper, the health and life of transformer can
be assessed.
Search for patent literature for DP of cellulose insulating paper revealed the
following patent documents.

PAT. NO.(US)

Titie

16,898,067 Electric double-layer capacitor
26,841,232 Reinforced wallboard
36,424,5171 Electric doubie layer capacitor
46,411,496 Electric double layer capacitor and separator therefore
56,344,514 Binder for non-woven fabric
66,242,524 Binder for non-woven fabric
76,104,600 Electric double layer capacitor
85,049,435 Flexible sheet reinforced with poly (aromatic amide)
non-woven fabric and use thereof
94,897,301 Flexible sheet reinforced with poly (aromatic amide)
non-woven fabric and use thereof.
The traditionais steps as disclosed in the art to assess DP of cellulose paper
being a!! manual, cumbersome, time consuming are prone to human error and all
the methods are confined to Lab only and none of the said prior arts do not
indicate anything of conducting estimations at site without involvement of
manual operation and do not say anything about automated equipment which
can perform all the traditional steps mentioned above to calculate DP of cellulose
paper.

In the traditional steps as narrated above to estimate the viscometric time,
viscometers with two annular reference marks on the measuring tube are used
and the flow time of the liquid meniscus between the two marks was measured
manually with a stop watch. Numerous other methods for observation or for
sensing when the liquid meniscus passes a reference mark have also been
suggested and used. All methods employing visual observation are prone to
subjective measuring errors by the measuring individual and to measure time the
viscometers has to be kept in a constant temperature bath maintained at 20°C.
OBJECTIVES OF THE INVENTION
In the above background the invention has proposed to develop an automated
machine to estimate the DP of cellulose paper in situ.
According to main objective of the invention ail the traditional steps to estimate
the DP of the cellulose paper are automated by developing a prototype
automated machine thus avoiding any human error which are likely to creep in at
any stage and hamper the end result.
According to another objective of the invention the steps of estimation of DP are
carried out by combining two broadly classified categories namely -
1, Pre processing of cellulose based paper and
2. DP measurement, wherein the first category is achieved by developing a
hardware controlled by a electronics circuit and the second category is
carried out with the help of a separate hardware controlled by another
electronics circuit.

According to yet another objective of the invention the drawback of prior art tc
maintain a constant temperature of the viscometer kept in a bath is overcome.
According to a stiil further objective or the invention computer gathers data from
the insitu testing and DP is calculated through a software incorporated therein.
DESCRIPTION OF THE INVENTION
An automated machine with controi circuit has been developed for preprocessing
of cellulose based insulating papers integrated with means for estimating DP of
said papers.
According to the invention there is provided an automated machine integrated
with a PC and control circuits for estimation of degree of Polymerisation (DP) of
cellulose based paper insulation of a transformer collected by cutting the paper
from leading ends of a transformer and conveying the said collected papers
through the automated machine comprising
a) a first set of rollers for squeezing oil from the test insulation paper,
b) a second and third set of rollers for cleaning the paper with the help of a
suitable solvent,
c) a fourth set of rollers adapted with heating means for drying the sample
paper wherein a heater is provided separately with a controller and an electronic
circuit,

d) a shredding means arranged and adapted with punches for cutting the
paper into small circular pieces,
e) a paper chips chute conveyor for transporting the small pieces of paper to
a digital moisture balance to weigh the initial weight and dried out weight of the
paper sample and estimating the moisture content of the paper,
f) a fifth set of rollers being arranged to drag out the paper out of the
machine,
g) an integrated PC with a control circuit via a RS 232 port to operate and
control components a) to f),
h) a glass flask containing a predetermined amount of DM water and copper
ethylene diamine (CED) wherein the pre-weighed and dried paper sample pieces
are put into the solution and the glass flask kept in a shaker assembly is shaken
till the sample is dissolved completely,
i) a pre-calibrated viscometer calibrated with predetermined amount of
blank solution of CED and water wherein the recording of efflux time for biank
and sample solution being done via a sensor by noting a signal generated from
the 1st mark and actuating a timer circuit by the said 1st signall and noting a
signal generated from the 21'1 mark when the liquid meniscus touches the said
2na mark and stopping the timer of the said 2m signal,

j) a built In digital and analog I/O computer (CPU) with control circuit to
record the time elapsed for the ist and 2nu mark to give a measure of viscosity of
the solution, DP of the sample paper via a software developed using Martin's
curves.
According to the invention there is also provided an automated method of
estimation of DP of cellulose based paper insulation of a transformer comprising
the steps of
a) collecting by cutting the paper from leading ends of a transformer and
feeding it through an automated cellulose paper processing machine in
sequential steps of
b) squeezing the oil from the test insulation paper by a first set of roller,
c) cleaning the paper with the help of a suitable solvent through a second
and third set of rollers,
d) drying the sample paper through a fourth set of rollers adapted with
heating means,
e) cutting the paper into small circular pieces by a shredding mechanism
arranged and adapted with punches for cutting the test paper into small circular
pieces,
f) weighing the initial and dried out weight of the paper sample and
estimating out the moisture content of the paper after transporting the small
pieces of paper by a paper chips chute conveyor to a digital moisture balance,

g) dragging out the paper out of the machine by a fifth set of rollers,
h) dissolving completely the pre-weighed and dried paper sample pieces by
putting them in a glass flask containing predetermined amount of DM water and
CEO and shaking the glass flask kept in a shaker assembly,
i) recording the effiux time for blank and sample solution via a sensor by
noting a signal generated from the Is' mark and actuating a timer circuit by the
said Is' signal and by noting a signal generated from the 2nd mark when the
liquid meniscus touches the said 2i|d mark and stopping the timer by the said 2nd
signal, through a precalibrated viscometer calibrated with predetermined amount
of blank solution of CED and water and
j) recording time elapsed for the said l3t and 2Kj mark in a built in digital
and analog I/O computer, to give a measure of viscosity of the solution, DP of
the sample paper through a software developed suing Martin's curves,
all the steps of b) to g) being operated and controlled through an integrated PC
with control circuit via a RS 232 port and steps h) to j) are operated and
controlled with control circuit via a built in digital and analog I/O computer.
Cellulose insulating paper sample is taken out from the load ends of service
transformers. The same is fed in the automated machine developed according to
the invention. The sample is first fed to first set of rollers for squeezing the oil
from the paper containing oil. For this operation to be carried out mini rollers are
fabricated and set in the machine. Second and third set of rollers are arranged in

the machine for cleaning the papers with the help of a suitable solvent. The said
second and third set of rollers are adapted with solvent mats preferably
containing toluene to squeeze out the remaining oil and to make the paper free
from oil. Further, the paper is pressed between filter pad rollers to remove the
traces of solvent. The said sample papers are then fed into a fourth set of heated
roillers for drying the paper. Heating arrangement for drying the paper is made
by providing heaters adjacent the said set of roller and said heating is controlled
via a controller by a control circuit. The dried out transformer paper is then cut
into small circular pieces preferably 6 mm dia by a shredder mechanism to
enable the papers to be dissolved into the solvent Copper Ethylene Diamine
(CEO) easily. This operation is achieved by fabricating a shredder assembly and
adapting in the machine in a suitable location. The said shredder mechanism
contains sharp punches which cut the paper into small circular pieces. These
small pieces are then transported into a moisture balance by a mini
conveyor/chute conveyor. This chute conveyor Is provided below the shredder to
transfer the paper chips to the weighing machine/moisture balance. Suitable
conveyor is fabricated and adapted in the machine and the said conveyor allows
the small paper pieces to fall directly into a glass dish kept on the platform of
moisture balance. The chute conveyor along with the paper shredder is operated
through a R5 232 port/receiver The said conveyor is operated through a 12V-1.5
amp DC solenoid for tripping the paper chips. The paper schredder is operated
by a solenoid which is controlled through the RS 232 port.
jAil the above narrated operations are conducted in an automated way through
computer controlled equipments via electronic control circuit which controls the
operations of rollers, heater, shaker and mini compressor.

The moisture balance takes initial weight of paper sample, the recorded weight is
then communicated to the computer via RS 232 Receiver. The paper pieces are
heated generally by Infra Red method to remove moisture and the final weight is
again taken in situ and the moisture content of the paper and also the weight of
dried sample paper are computed for consequent analysis. These datas are again
fed to the computer.
The pre-weighed and dried paper sample pieces are then taken in a giass fiask
containing solution of copper ethylene diamine (CED) added to DM water and the
said solution is introduced into a pre-calibrated U tube viscometer wherein the
calibration is made by measuring the efflux time between the two marks on
viscometer with blank solution of CED and the sample solution and water and the
run time are fed to the computer through which signals generated for 1st mark
and 2nd mark actuates and stops a timer respectively embedded in the control
board. The recorded time elapsed between the 1st and 2nd marks gives a
measure of viscosity through a software developed using Martin's curves for this
purpose to calculate intrinsic viscosity, specific viscosity of the sample solutions
and DP of the sample paper.
The above narrated invention will be better understood from the following
description with reference to the accompanying drawings in which
Figure 1 represents the front elevationai view of the cellulose paper processing
machine with various equipments to carry out pre processing of cellulose based
paper of a transformer for final estimation of DP of the same.

Figure 2 represents the eiectronlc layout circuit with schematic representation of
operations performed by the cellulose paper processing machine hardware.
figure 3 represents a schematic diagram of operating the hardware for DP
measurement.
Figure 4 represents an electronic circuit layout to control the operations of
hardware for DP measurement.
In Figure 1 there is arranged a first set of rollers (1) which squeezes oil from the
sample insulation paper cut from a transformer. A second and third set of rollers
(2&3) are adapted in the machine for cleaning the paper with the help of a
suitable soivent. The said rollers are adapted with solvent mats containing
toluene to squeeze out the remaining oil and also traces of solvent and clean the
paper free from oil and solvent. A fourth set of rollers (4) is adapted to dry out
the paper arranged with heating arrangement (H). The heating means is usually
a heater (H) rated at 23QV-125W, through v^hich hot air is supplied to the rollers
(4) for solvent drying. After the fourth set of rollers positioned a shredder
mechanism (SM) which cuts the paper into small uniform 6mrn dia disces. The
shredding assembly (SM) contains round button sharp punches (8) operated by a
solenoid to enable the paper to be cut into small circular pieces. The solenoid
(SL) for operating the paper punch is operated at 230V. The transformer test
paper is cut into small pieces to enable it to be dissolved in a solvent of copper
ethylene diamine (CED) easily in the later stages of processing. The small pieces

are then transported into a digital moisture balance/ weighing machine (w)
through a mini conveyor paper chips chute conveyor (C) which allows the small
paper pieces to fall directly into a glass dish kept on a platform of the moisture
balance (W). The chute (C) is provided below the shredder (SM) to transfer the
paper chips to weighing machine. This chute conveyor is operated through a RS
232 port/receiver. The chute conveyor operates through a 12V-1.5 amp DC
solenoid (S) for conveying paper chips to the chute conveyor by tripping. A fifth
set of rollers (5) is adapted in the machine to drag the paper out of machine. In
all the five sets of rollers gap between them is adjustable and ail the said rollers
are capable of moving in forward and backward directions.
Fig. 1 shows the assembly of the automated equipment consisting of five sets of
rollers (1 to 5) heating device (H) and the paper shredding mechanism, ail the
said elements including solenoids (SL and S) and weighing means are being
operated in an automated way and controlled by a control circuit (Fig.2) through
a PC. The control circuit is provided in a separate box on a control board, AH the
said rollers (1 to 5) are rotated by a servo motor (7) through a train of gears
having gear dimension Z=25, rn-i (Pcd 25). The servo motor with 115 mm
roller width operated at 230V and with two output shaft diameters 10mm and
15mm is shown separately in Figure 1.
All the operations explained above are performed through a PC. As the
equipment is expected to work in an industrial environment, PC has been used
keeping in view its ruggedness, open-type of architecture and ease of
programming. The control action from the PC requires reading of digital inputs,
like output of weighing machine, from the process and generating digital output
for operations like - compressor ON/OFF, Motor for rollers ON/OFF, Motor
direction, Heater, Shaker etc as shown in Figure - 2.

To enable the PC to communicate effectively, an interface hardware using a
micro-controller, with digital I/O capability, has been used. All these digital I/O
data are optically isolated to avoid any noise from the process side affecting the
electronics. This hardware in turn communicates with the PC through an RS 232
serial port.
The power supply requirement for operating the micro controller based interface
hardware, optical isolation of the hardware from the process and the actuation
circuits like relays and solenoid valves is met by using a power pack generating
+5Vf +/'- 12V from 230V AC input as shown in Figure - 2.
The moisture balance takes initial weight of paper sample and the measured
value is communicated to a computer (CPU) through RS 232 Receiver. The paper
pieces are heated to remove moisture by a heater (H) and the final weight is
again taken in - situ which gives the moisture content of the paper sample and
also the weight of dried sample taken for analysis. These dates are again fed to
computer with monitor. The pre weighed and dried paper sample pieces are then
taken in a glass flask/solvent tray (6) and 22.5 ml of DM v/ater is added, shaken
for half an hour in a wrist shaker in a separate box (see Hg.2) and 22.5 ml of
topper ethylene diamine (CED) is added. A small air compressor (not shown) is
connected to RS 232 Port, Air fjom the compressor is passed through the
separate container (6) having pyrogailoi solution (CED) for removing oxygen
present in the air and thus maintains an inert atmosphere of Nitrogen over CED.
Water and CED are added by a dispensor and a digital burette or through a
peristaltic pump. The contents of the flask is shaken in a shaker till the sample is
dissolved. A paper shaker assembly is fabricated for this purpose which is
controlled through PC.

When the water is totally dissolved, 10 ml of this paper solution will be
introduced into U tube viscometer which is pre-calibrated with blank solution of
CED and water and by measuring the efflux time between the two marks on
viscometer the run time is fed to the computer. The recordings of efflux time for
blank and sample solution is achieved by conductive sensor between two marks
(see Fig.4). The signal generated from the 1* mark is noted and is actuated by a
timer circuit. When the meniscus of the liquid touches the 2nd mark, the signal
generated stops the timer.
The measurement of DP of the sample paper can best be understood from the
schematic diagram of operating the hardware as shown in Figure 3 and
electronic control circuit layout to control the hardware of Figure 2 for DP
measurement.
The sequence of operations required to do the DP measurement is carried out
using a SBC BL 2020 computer (CPU) which is a high performance single board
computer built in digital and analog I/O. This hardware is built around the 8 bit
Rabbit - 2000 microprocessor (see Figure 4) operating at 22.1 MHz.
The outputs fro BL2020 are high-current sinking digital outputs, which are used
to operate various pumps and solenoid valves in a predetermined sequence to
achieve DP measurements. Each of these outputs is buffered through a driver
circuit consisting of HPH transistors (SL 100) (see Fig,4) with the relay coil
connected in the collector circuit. The contacts of these relays are wired in series
with the power supply to the device, which is to be actuated. Since the pumps
used are. required to operate in both forward and reverse mode, a changeover

contact has been used, in which the Normally Open (NO) contact is used for
forward direction and the Normally Closed (NC) contact for the reverse direction,
thus facilitating a single reiay to control motion in both the directions. Similarly,
each of the two position solenoid valves is controlled by a single output through
a changeover contact. In Fig. 4 the various interconnections to the hoard are
done through the terminal blocks marked as 32, 34, 38, 39 etc as shown in the
drawing. The terminal block 39 is for the output connections marked as OUTO-
OUT7. There is onboard relay present on the SBC (single board computer) whose
terminals are brought out through NO, COM &. NC points on the terminal block
39. This relay, however, is meant for future requirement. Each of the outputs
QUTQ through OUT? drives an SL 100 drives an St. 100 transistor which is a 3
terminal device viz base, emitter ana collector. The relay coils form the load in
the collector arcuit which is activated whenever the SBC makes the
corresponding output high. A free wheeling diode, connected across the coil of
each relay, helps to provide a path for the current whenever the transistor is
switched off, thereby avoiding damage to the transistor. In the terminal block 38,
points 1 & 2 are for reading the status of the digital inputs which given an
indication about the liquid flow. A display/keypad interface device (PSMT) is used
in this equipment for the purpose of programming and viewing the various
values. This device gets interfaced to the SBC through the points 1 6*. 2 on the
terminal block J2. RXB & TXB stand for RECEIVE & TRANSMIT respectively. The
interface on the PSMT side is an RJD connector which is translated to a D-type
connector before getting connected to the SBC through J2.

In Figures 3 and 4 Pi, P2, P3, P4 are peristaltic pumps; SVl, SV2, SV3 are 3 way
solenoid valves; SI, S2 are platinum sensors; Fl, F2 are glass flasks and CED is
the copper Ethylene Diamine. Peristaltic pumps are used to fiil up flasks Fl and
F2 with water and CED in correct amount operated through 3 way solenoid
valves SVl, SV2 and SV3 and signals IN2 and IN3 are generated through sensors
SI and S2, which signais are computed in digital analog I/O computed to give a
measure for DP.
The crossing of the mensscus between the two marks is detected by inserting
two platinum wires (51 and S2) of about 0.5mm diameter into the capillary at
the corresponding levels. One end of the wires is connected to +24 VDC. The
other ends are connected to two digital inputs (IN2 & IN3). When the liquid is
above any of the set. marks, the corresponding digital input senses a logic high
since the liquid forms a conducting medium. Similarly, when the liquid is below
any of the set marks the corresponding digital input reads a logic low since air is
a bad conductor. The digital input status remains high as long as the liquid level
is above them and changes to low once the level goes below them. The time
taken for the meniscus to cross between the two set limits is measured through
the software delay. The timer is initiated when the meniscus crosses the upper
limit, which is detected as a high to low transition on the digital input, IN2 in
Fig.4. The timer is stopped when the meniscus crosses the lower limit, which is
again sensed as a high to low transition on the other digital input, IN3 in Fig.4.
The contents of the timer register gives the time taken by trie meniscus to go
from one level to the other.

In the present invention the distinguishing principle used for measuring the
viscometric time is conductivity measurement to detect the presence or absence
of the liquid. The time of flow of liquid when passing through capillary was
measured by starting a timer when the iiquid meniscus crosses the first mark on
viscometer and stopping the timer when the meniscus reaches the 2nd mark. The
time elapsed gives a measure of the viscosity of the liquid.
Once the time of blank liquid runs and sample solution run are available with
computer, the computer calculates the DP of paper using other parameters, like
weight of sample, moisture content. A software programme has been developed
to calculate from the above 6ata, the intrinsic viscosity, specific viscosity, and DP
using Martin's curves. This software also makes appropriate temperature
corrections in the final DP,
The invention is enumerated by the following examples illustrating comparison of
DP calculations by software and by manual method.
Example -1
Paper solution efflux time : 134 sec.
measured by viscometer
CED Solvent efflux time (blank)
measured by viscometer : 93 sec.
Moisture : 1%

Weight of paper sample taken

0.0 3gm

DP value estimated by developed software
as per IEC600450 : 783.0
OP vaiue calculated by manual method
as per IEC600450 : 783.8
Example-2
Paper solution efflux time
measured by viscometer : 110 sec.
CED Solvent efflux time (blank)
measured by viscometer : 92 sec.
Moisture : 2%
Weight of paper sample taken : 0.025gm
DP value estimated by developed software
as per IEC600450 : 439,43
DP vaiue calculated by manual method
as per IEC600450 : 438.7

The end results carried out through test revealed that the DP value accuracy
may be corrected in the order of ±4-to 5 which enables an operator in an
industrial production floor to take steps of correction or replace transformer oil to
maintain health of a transformer.
The equipment is integrated through PC and arranged in a panel for easy
operation and all the traditional steps of estimating DP of cellulose paper of
transformer have been automated.
In prior art, viscometers are to be kept at 20 °C in a constant temperature bath
while measuring the viscometric flow time between the marks. This has been
soived by present invention incorporating the temperature correction software
and thus on site measurements of the viscometric time, at ambient temperatures
ranging from 15 to 30 °C can be recorded and the software developed will make
the appropriate temperature corrections in the DP and gives values at 20QC.
The invention as described hereinabove and illustrated with an embodiment and
examples should not be read in a restrictive manner as various adaptations,
modifications and changes are possible as encampused within the scope of the
appended claims.

We Claim:
1. An embedded device for direct determination of degree of
Polymerisation (DP) of cellulose based paper insulation of a transformer,
the device comprising:
a) a first set of rollers (1) for squeezing oil from a test sample of the
insulation paper inputted to the device;
b) a second and a third set of roller (2&3) for cleaning the paper with
the help of a suitable solvent, being supplied to the rollers (2,3);
c) a fourth set of rollers (4) adapted with heating means (H) for drying
the sample paper wherein a heater is provided separately with a
controller and an electronic circuit,
d) a shredding means (SM) arranged and adapted with punches (8)
for cutting the dried sample paper into a plurality of pieces;
e) a chute conveyor (C) for transporting the plurality of pieces of paper
to a digital moisture balance (W), to weigh the initial weight and
dried out weight of the paper sample, and estimate the moisture
content of the paper;
f) a fifth set of rollers (5) arranged to drag out the test paper out of the
machine;

g) a glass flask (6/F1 & F2) containing a predetermined amount of DM
water and copper ethylene diamine (CED) wherein the pre-weighed
and dried paper sample pieces are put into the solution and the
glass flask kept in a shaker assembly is shaken till the sample is
dissolved completely;
h) a pre-calibrated viscometer calibrated (1,2,3) with predetermined
amount of blank solution of CED and water wherein a recording of
an efflux time for the blank and sample solution is done via a
sensor through actuating a timer circuit, the signal generated at the
first (1) mark and the signal generated at the second mark (2)
enables to determine the efflux time;
characterized by comprising a control means having a control circuit, input
/output means, RS-ports including a display means with embedded software
structure which allows generating the signals representing the efflux time for the
blank including that of the sample solution, recording the elapsed time and direct
determination of viscosity of the solution, and a degree of polymerization of the
sample paper.
2. The device as claimed in claim 1, wherein the chute conveyor is provided
below the shredding mechanism which operates through the RS 232 port, via a
12V-1.5 amp DC solenoid (S), and wherein the five sets of roller are driven by a
servomotor (7) through a train of gears.

3. The device as claimed in claim 1, comprising an air compressor supplying
compressed air through a container (6) containing pyrogallol solution to remove
oxygen present in the container (6) such that an inert atmosphere of nitrogen
over the CED solution to be employed for the evaluation of DP of the sample
paper is maintained.
4. The device as claimed in claim 1 wherein the sensors are platinum sensors
(S1 & S2).
5. An automated method for direct determination of degree of polymerization of
cellulose based paper insulation of a transformer in a device as claimed in claim
1, the method comprising the steps of:

a) collecting by cutting a test sample paper disposed at the leading
ends of a transformer and feeding the sample through the device;
b) squeezing the oil from the test insulation paper by a first set of roller
(1),
c ) cleaning the paper with a solvent through a second and third set of
rollers (2&3),
d) drying the sample paper through a fourth set of rollers (4) adapted
with heating means (H);

e) cutting the paper into plurality of pieces by a shredding mechanism
(SM) arranged and adapted with punches (8) for cutting the test paper
into the plurality of pieces;
f) weighing the initial and dried out weight of the paper sample and
determining the moisture content of the paper after transporting the
plurality pieces of paper via a chute conveyor (C) to a digital moisture
balancer (W);
g) dragging out the paper out of the device by a fifth set of rollers (5);
h) dissolving completely the pre-weighed and dried paper sample pieces
in a glass flask (Fi and F2) containing predetermined amount of
demineralized (DM) water and Copper Ethylene Diamine (CED) and
shaking the glass flask;
i) recording the effux time for blank and sample solution; and
j) determining the degree of polymerization (DP) of the paper insulation by
adapting the control means from the data related to viscosity of CED
solutions and DM water.
6) The method as claimed in claim 5 wherein measurement of viscosity of the
solution is carried out by a conductometric sensor to detect the presence or
absence of the liquid by measuring the time of flow of liquid when passing
through a capillary by a starting timer when the liquid meniscus cross the 1st
mark on viscometer and stopping the timer when the meniscus reaches the 2nd
mark.

7. The method as claimed in claim 5 wherein the software structure employed
provide data for temperature corrections in the DP.
8. The method as claimed in claim 7 wherein the viscometer is kept at ambient
temperatures ranging from 15°C to 30°C.
9. An embedded device for direct determination of degree of Polymerisation (DP)
of cellulose based paper insulation of a transformer, as substantially described
and illustrated herein with reference to the accompanying drawings.
10. An automated method of direct determination of degree of polymerization
(DP) of cellulose based paper insulation of a transformer as substantially
described and illustrated herein with reference to the accompanying drawings.

Documents:

00161-kol-2006-abstract.pdf

00161-kol-2006-claims.pdf

00161-kol-2006-description complete.pdf

00161-kol-2006-drawings.pdf

00161-kol-2006-form 1.pdf

00161-kol-2006-form 2.pdf

00161-kol-2006-form 3.pdf

00161-kol-2006-gpa.pdf

161-KOL-2006-ABSTRACT.pdf

161-KOL-2006-CANCELLED PAGES.pdf

161-KOL-2006-CLAIMS.pdf

161-kol-2006-correspondence.pdf

161-KOL-2006-DESCRIPTION (COMPLETE).pdf

161-KOL-2006-DRAWINGS.pdf

161-kol-2006-examination report.pdf

161-KOL-2006-FORM 1.pdf

161-kol-2006-form 18.pdf

161-KOL-2006-FORM 2.pdf

161-kol-2006-form 3.pdf

161-kol-2006-form 5.1.pdf

161-KOL-2006-FORM 5.pdf

161-KOL-2006-FORM-27.pdf

161-kol-2006-gpa.pdf

161-kol-2006-granted-abstract.pdf

161-kol-2006-granted-claims.pdf

161-kol-2006-granted-description (complete).pdf

161-kol-2006-granted-drawings.pdf

161-kol-2006-granted-form 1.pdf

161-kol-2006-granted-form 2.pdf

161-kol-2006-granted-specification.pdf

161-KOL-2006-REPLY TO EXAMINATION REPORT.pdf

161-kol-2006-reply to examination report1.1.pdf

abstract-00161-kol-2006_fig-1.jpg

abstract-00161-kol-2006_fig-3.jpg


Patent Number 248584
Indian Patent Application Number 161/KOL/2006
PG Journal Number 30/2011
Publication Date 29-Jul-2011
Grant Date 26-Jul-2011
Date of Filing 23-Feb-2006
Name of Patentee BHARAT HEAVY ELECTRICALS LIMITED
Applicant Address REGIONAL OPERATIONS DIVISION (ROD), PLOT NO :9/1, DJBLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI- 110049, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 TANGIRALA SITA RAMA MURTHY BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
2 TAMMINENI KRISHNAMA NAIDU BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
3 UTTARAMALLU YUGANDHAR BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
4 RACHAKULLU ANNAPURNA DEVI BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
5 MEENAKSHI BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
6 KANURU PRABHAKAR RAO BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
7 KOTAMARTHY VENKATA HANUMANTHA RAO BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
8 TUNGA SAI KUMAR BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
9 RAMANATHAN SETHURMAN BHARAT HEAVY ELECTRICALS LIMITED (A GOVERNMENT OF INDIA UNDERTAKING), CORPORATE RESEARCH & DEVELOPMENT, VIKASNAGAR, HYDERABAD-500 093, A.P., INDIA
PCT International Classification Number G09F
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA