This is seminar presentation gives about testing of transformer oil for copper sulfide

1. Visvesvaraya Technological University
Jnana Sangam Belgaum-590014
Department of Electronics and Electronic’s Engineering
GHOUSIA COLLEGE OF ENGINERRING
A seminar on
“Testing for Corrosive Sulfur Effect in transformer oil ”
Submitted in partial fulfillment of the requirement for the award of the degree
Bachelor of Engineering
in
Electrical & Electronic’s Engineering
presented by
SHIVAKUMAR.S
(USN: 1GC08EE049)
Under the guidance of
Mr. Faheem Ahmed Khan
Asst. Prof,
Dept. of E&E, GCE, Ramanagara
Department of Electronics and Electronic’s Engineering
Ghousia College of Engineering
Ramanagara –562159
2011-2012

2. have been a number of failures of
Department of Electronics and Electronic’s Engineering power transformers and reactors, due
to formation of copper sulfides on
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conductors and insulating materials.
The conductive copper sulfide
reduces the dielectric breakdown
voltage of the solid insulation.
This can result in a dielectric
puncture through the paper
insulation.

3. Department of Electronics and Electronic’s Engineering •At normal operating temperatures the
corrosion process will take time to
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form conductive sulfides.
•This problem in the transformer is
difficult to detect and manage,
because the failures have occurred
without prior evidence of abnormal
gassing behavior.
•This problem is mainly present in the
large power utilities.

4. susceptible?”
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•In response to the above question,
Doble has developed the following list.
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(1) Units that have the following
characteristics
a)Manufactured from 1999 to
present.
b) Operate at high temperatures
over long periods of time.
c)Are either gas blanketed or have a
sealed conservator system.
d)Have oils that fail the corrosive
sulfur .
2) Those unit that do not have

5. 3)In the fast several years, in response to this problem,
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there has been a great deal of research activity in
developing new test to help identify oils with the potential
to have corrosive sulfur problems
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.
 some of the tests are in various stages of development
and are broken down into two groups.
1. Oil tests.
2. Transformer Electrical test.

6. Department of Electronics and Electronic’s Engineering
 These test is to determining if corrosive sulfur
compounds are present in the oil or not.
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Identifying sulfur compound that are presently stable but
may become corrosive under conditions that exist in
the transformer.
A listing of some of the oil tests used with descriptions
follows.

7. Department of Electronics and Electronic’s Engineering
 This test ages 220mls of oil in contact with a copper strip in a
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sealed vessel for 48 hours at 150 deg C as shown.
 The primary purpose of the test is to determine if any corrosive
sulfur compounds present in the oil.

8.  If the corrosive sulfur compounds present in the oil, then the oil will
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react with the copper strip to turn it gray or black as shown below.
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Noncorrosive Strip Corrosive Strip
 In the above figure the lift side is the strip before immersed in the
sealed vessel & right side is the strip after removal from the sealed
vessel after 48 hours at 150 deg C.
This is a very routine test.

9. 2)Sulfur speciation:
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GHOUSIA COLLEGE OF ENGINERRING
 This test is performed by gas chromatography with
sulfur selective detection and covers the detection
of volatile sulfur-containing compounds.
 This test can be used to isolate specific sulfur
compounds, some of which may or may not be
responsible for corrosive sulfur attack.
 There are thousands of sulfur compounds, and this
test does not have the ability to cover them all.
 It is usually not considered a routine test and mostly
used for research purposes.

10. 3)Total sulfur in oil:
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There are several tests that can be used for the
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detection of total sulfur in oil.
This test determines the total amount of sulfur in
the oil.
But in this method it does not determine whether
or not the compounds being detected are
corrosive.
This is a routine test, but it only provides
information on how much sulfur in the oil.

11. 4)Mercaptans in oil:
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Mercaptans are sulfur compounds that can be very corrosive.
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This is a potentiometric titration test that is used to determine
the concentration of mercaptans compounds.
From this test it is not able to identify specific compounds.
This test is used in the fuel and lubrication industries often
and is starting to be used in the transformer oil industry.
The problem with mercaptans is that some of them are highly
volatile and thus not easily sampled.
It is presently not routine test.
.

12. 5)Doble Covered Conductor Deposition (CCD) Test, Doble Test
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 This test is conducted by taking an abraded copper road and wrapping new
Kraft paper insulation around the rod as shown in the figure below.
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 Then they are placed in 20 mL headspace vials.
 Oil is added and then the vials are sealed as shown below.

13. CONT……
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• A stainless steel needle of a particular diameter is then pierced through the
spectrum of one vial and left there to allow air ingress during testing as shown
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in figure.
• The vials are then tested at 140 deg C for four days.
• At the end of the test cycle , the vials are removed and the copper rods with
paper retrieved.

14. Cont…..
Department of Electronics and Electronic’s Engineering  The paper is then removed from the copper as shown in the figure below.
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• Then washed in a solvent to remove the oil.
• The road is inspected to determine if it has been tarnished by corrosive
sulfur, and the paper is inspected to determine if deposition as occurred.
• The presence of deposition in the paper is important as most of the recent
transformer failures have been due to copper sulfide deposits in the paper
causing a severe reduction in dielectric strength.
• The resulting “deposition,” whether heavy, moderate, or light, means that
the interaction of the copper and oil with the paper insulation.
• This is becoming a very routine test.

15. Conclusion
epartment of Electronics and Electronic’s Engineering  These test will be used to screen out or identify
oils that may not be suitable.
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D

16. GHOUSIA COLLEGE OF ENGINERRING
Department of Electronics and Electronic’s Engineering
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