condition mon oil
TRANSCRIPT
-
7/31/2019 Condition Mon Oil
1/45
CONDITION MONITORIN
TRANSFORMER OIL
-
7/31/2019 Condition Mon Oil
2/45
Parameters for condition monitoring of oil service
Two ways are available to an operating enginee1. To make periodic oil tests to establish trends an
them.
2. To conduct dissolved gas analysis to assess the
condition of transformers
PARAMETERS TO BE CHECKED ARE:
1. FLASH POINT
2. DIELECTRIC DISSIPATION FACTOR
3. SPECIFIC RESISTANCE
4. NEUTRALISATION.
5. MOISTURE CONTENT6. SLUDGE %
7. BREAK DOWN VOLTAGE
8. D.G.A.
-
7/31/2019 Condition Mon Oil
3/45
PHYSICAL CONTAMINATION
1. Dust, fibre, metallic, particles, other solid impu
2. Dissolution of varnish.
3. Free and dissolved water.
CHEMICAL DETERIORATION
Oxidation resulting in acids sludges and pimpurities.
CONTAMINATION OF GASES
a) Dissolved air from atm. Nitrogen, co
b) Generated in oil, methane, ethane, a
ethylene etc.Before the oil is put in
transformer, its properties should b
ensured.
-
7/31/2019 Condition Mon Oil
4/45
-
7/31/2019 Condition Mon Oil
5/45
-
7/31/2019 Condition Mon Oil
6/45
-
7/31/2019 Condition Mon Oil
7/45
CHEMICAL DECOMPOSITION OF
HYDROCARBONS
Catalyst
RH R* + H
(Hydrocarbon) (Free radical
R* + O RO
(Peroxy radic
RO2* + RH RO2*H+ R
(Hydro per o
-
7/31/2019 Condition Mon Oil
8/45
2 RO2*
R* + RO2*
2 R*
Oxidation prod
(Higher TempeIons as catalys
the reaction)
Hydrocarbon RH first produces a free radical R. T
now combines with the available oxygen giving pe
First product of oxidation peroxides reacts with any
(RH) giving hydro peroxide RO2H and another fre
this type of chain propagation continues till thebroken adding suitable inhibitor.
-
7/31/2019 Condition Mon Oil
9/45
SERVICE OIL TESTS
The service oil tests to be conducted are furnished
Service oil tests as per IS: 1866 2000
Sl. No. TESTSINFORMATION PRO
TESTS1
Interfacial Tension Sludge present in the oil
2Neutralisation Number Acid present in the oil
3Moisture content (ppm)
Reveals total water cont
cellulosic deterioration.
4Flash point
Sudden drop in flash poiunsatisfactory working c
transformer.
5 Sludge Indicated deterioration
-
7/31/2019 Condition Mon Oil
10/45
6Dielectric Dissipation
Factor
Reveals presence of mo
varnishes or their produ
in oil
7 Dielectric strengthConductive contaminan
present in the oil.
8 Resistivity Indicative of conductin
9 Dissolved Gas Analysis
Reveals ppm of combu
dissolved in the oil to a
condition of the transfo
-
7/31/2019 Condition Mon Oil
11/45
A Typical Method to Maintain Test Record for T
TRANSFORMER DATA OIL DA
Location Oil supplierManufactures Name Code Designation
Manufactures Number. Inhibited or
Un-inhibited
Users reference
Number of phases. Type of Inhibitor
If present
Voltage Ratio
Outdoor or Indoor.
Type of cooling. Quantity of oil in
The system
With or without Conservator
Type of Breather
-
7/31/2019 Condition Mon Oil
12/45
INSTALLATION DATA
Filled on.
Commissioned on..
Maximum load...
Maximum oil temperature..
Normal load
Normal Oil Temperature
-
7/31/2019 Condition Mon Oil
13/45
MAINTENANCE OF DATA
1. Date of sampling..
2. Topping up done up.
Type and quantity of oil added
3. Note on abnormal operations...
4. Oil filtered on...5. Breather reconditioned on
6. Physical observation
-
7/31/2019 Condition Mon Oil
14/45
7. Tests conducted:
a. Interfacial Tension.
b. Neutralisation Number
c. Moisture content (ppm)
d. Flash point
e. Sludgef. Dielectric Dissipation Factor
g. Dielectric Strength
h. Resistivity
-
7/31/2019 Condition Mon Oil
15/45
TABLE 1: APPLICATION AND INTERPRE
TESTS ON OIL IN TRANSFORMERS
AS PER IS: 1866 1983
Sl.
N
o.
CharacteristicEquipment
voltage
Permissible
limit,
satisfactory for
use
1 Specificresistance at
90 c ohm-
cm, min
All
voltages0.1 * e12
2
Dielectric
dissipationfactor at 90 c,
max
> 145 kv< 145 kv
0.21.0
-
7/31/2019 Condition Mon Oil
16/45
Sl.
NoCharacteristic
Equipment
voltage
Permissible limit,
satisfactory for use
3
Neutralization
value,
mg / KOH / g
All
voltages0.5
4Precipitate
sludge
All
voltages
No perceptible
sludge
5 Flash pointAll
voltages
Decrease in flash
point 15c (max) of
the initial value,minimum value
125 c
-
7/31/2019 Condition Mon Oil
17/45
Sl.
N
o
CharacteristicEquipment
voltage
Permissible
limit,
satisfactory foruse
6
Interfacial
tension at
27c, n/m,
min
All
voltages0.015
7Electric
strength
145 kv +
above
< 145 kv
> 72.5 kv
< 72.5 kv
50kv min
40 kv min
40 kv min
30 kv min
8Water
content ppm
> 145 kv
< 145 kv
25 ppm
35 ppm
-
7/31/2019 Condition Mon Oil
18/45
LIMITING VALUES IS: 186
Test Equ. Voltage Method
Electric strength
> 145 kv
< 145 > 72.5
kv< 72.5 kvIs: 6792
Water content
ppm, max
> 145 kv
< 145 kv Is: 335
Specific
resistance @ 90,10 E12 ohm, cm All voltage Is: 6103
Tan delta @90,
max
> 145 kv
< 145 kvIs: 6262
-
7/31/2019 Condition Mon Oil
19/45
ACIDITY mg
KOH / g, Max
ALL
VOLTAGEIS: 1448
IFT, N/m. MinALL
VOLTAGEIS: 6104
FLASH POINT
Deg C, Min
ALL
VOLTAGE
IS: 1448
Max Dec 15
SEDIMENT
AND / OR
PRECIPITABLESLUDGE
ALL
VOLTAGE
IS: 1866
FOR TRANSFORMERS IN SERVICE
-
7/31/2019 Condition Mon Oil
20/45
Properties Condition Reme
Breakdown
voltageLow
Filtration und
+ temperatureMoisture High
Dielectric
dissipation
factor
HighFiltration as a
cause is moisVolume
resistivity Low
IFT Low Reclamation
GENERAL
-
7/31/2019 Condition Mon Oil
21/45
NV HIGH
FP LOWINVESTIGATE T
CAUSE
SLUDGE % HIGH DE-SLUDGING
-
7/31/2019 Condition Mon Oil
22/45
SUGGESTED LIMITS FOR IN SERVICE OILS GROUP I BY
BASED ON IS: 1866-1983
LIMITS_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
VOLTAGE CLASS
PROPERTIES
145 KV & 72.5 KV
ABOVE & < 145KV
ELECTRIC STRENGTH 50 40
(MIN) (MIN)
NEUTRALISATION VALUE 0.1 0.1
(mgKOH/g) (MAX) (MAX)
INTERFACIAL TENSION N/m 0.015 0.015
(MIN) (MIN)
DIELECTRIC DISSIPATION 0.2 1.0
FACTOR AT 90 C (MAX) (MAX)
WATER CONTENT, ppm 25 35
(MAX) (MAX)
SPECIFIC RESISTANCE
Ohm-cm 0.1x1012 0.1x1012
-
7/31/2019 Condition Mon Oil
23/45
Suggested limits for in service oils group ii by
(reconditioning) based on
IS: 1866-1983
LIMITSVOLTAGE CLASS
PROPERTIES - - - - - - - - - - - - - - - - - - - - - - - - -
145 KV & 72.5 KV
ABOVE & < 145KV
Electric strength < 50 < 40
Neutralisation 0.1 0.1
Value (mg.KOH/g) UPTO 0.5 UPTO 0.5
Interfacial < 0.015 < 0.015
Tension N/m (MIN) (MIN)
Dielectric dissipation > 0.2 > 1.0
Factor At 90 C
Water Content, ppm > 25 > 35
Specific resistance < 0.1 x1012 < 0.1 x1012
Ohm-cm
-
7/31/2019 Condition Mon Oil
24/45
TABLE IV
Suggested values for in-service oils group II by volta
(reconditioning) based on IS: 1866 (1983)
LIMITS
Voltage C
Properties
145 Kv & 72.5 Kv
Above & < 145kv
Electric Strength < 50 < 40
Neutralisation Value 0.1 0.1
(mg KOH/g) Upto 0.5 Upto 0.5
Interfacial Tension < 0.015 < 0.015
N/m
Dielectric Dissipation > 0.2 > 1.0
Factor at 90 C
Water Content, ppm > 25 > 35
Specific Resistance < 0.1 < 0.1
Ohm-Cm
-
7/31/2019 Condition Mon Oil
25/45
GROUP III OILS:
To categorize under group III, the paramete
well beyond the limits proposed in table IV
should be initially filtered under vacuum an
to verify whether the properties improve or
properties like Dielectric Dissipation Facto
Tension do not improve on filtration, then t
for oil to be replaced.
-
7/31/2019 Condition Mon Oil
26/45
Properties of oils evaluated in transformer
Sl.No Voltageclass BDV Tan Delta Resistivity
1 33 / 11 18 0.0321 0.914E12
2 66 / 11 38 0.0392 0.046E12
4 220 / 11 27 0.0108 2.75E12
5 220 / 11 35 0.263 0.912E12
-
7/31/2019 Condition Mon Oil
27/45
Properties of oils evaluated in transformer
Sl.
No
Voltage
class BDV
Tan
Delta Resistivity I
16 220 / 66 45 0.0032 6E12
17 66 / 11 47 0.0063 5.86E12
18 66 / 11 11 0.014 2.68E12
19 66 / 11 8 0.039 2.18E12
20 66 / 11 24 0.023 1.76E12
-
7/31/2019 Condition Mon Oil
28/45
Properties of oils evaluated in transfor
utility oil to be replaced/reclaim
Capacity
in MVA
Voltage in
KV BDV
Tan
Delta Resistivity
533 / 11 29 1.000 0.0177
533 / 11
-1.050 0.0151
5 110 / 33 /
11
-0.820 0.0194
533 / 11 24 0.270 0.0643
533 / 11 29 1.050 0.0168
533 / 11 37 0.720 2.3700
533 / 11 44 1.170 0.0150
-
7/31/2019 Condition Mon Oil
29/45
Properties of oils evaluated in transfor
utility oil to be replaced/reclaim
Capacityin MVA Voltage inKV BDV TanDeltaResistivity
5 33 / 11 44 0.990 0.0175
5 33 / 11 30 0.370 0.0452
5 33 / 11 39 0.290 0.0589
5 33 / 11 33 0.190 0.0905
5 33 / 11 29 0.680 0.0227
C
-
7/31/2019 Condition Mon Oil
30/45
5 33 / 11 63 0.880 0.0187
5 33 / 11 27 0.775 0.0222
5 33 / 11 22 1.100 0.0157
5 33 / 11 18 0.620 0.0283
5 33 / 11 15 0.700 0.0243
-
7/31/2019 Condition Mon Oil
31/45
CONCLUSIONS
a. In view of the importance of service oil tests, al
be carried out as per IS: 1866 systematically andas a part of maintenance schedule, as no single t
indicator.
b. The periodic testing will help O & M personnel
databank and case histories of power Transform
c. Periodic testing will help to know the oil condit
know growing of any incipient faults by Dissolv
Analysis.
d. The preventive maintenance followed by all util
not only savings in O & M costs but also prevenpremature breakdown / Failures besides improv
system reliability.
-
7/31/2019 Condition Mon Oil
32/45
Test required to assess the level of oil degrad
Screening tests: - Laboratory evaluation can be m
performing screening tests at site.
The tests are:
1. Appearance
i. Colour
ii. Visible particlesiii. Haziness or cloudiness
2. Acidity by colour
CPRI acidity testing kit
3. Interfacial tension test
By field method
4. Quality index
By Myers method
-
7/31/2019 Condition Mon Oil
33/45
PORTABLE ACIDITY TESTING KIT
A portable acidity testing kit was developed by cpri
check the acidity of transformer oil at site
Procedure:
A) 1.1 ml of oil in a test tube.
B) Add 1ml of rectified spirit.
C) Shake well
D) Add 1 ml. of alkaline solution
E) Add few drops of universal indicator
F) Match the colour with the colour chart to arrive a
value.
Advantages: Test can be performed by semi skilled p
the site of transformer / remote areas.
-
7/31/2019 Condition Mon Oil
34/45
SHAPES OF SPOTS
OIL ALONE INDICATOR
NEW OIL + INDICATOR SERVICE OIL
SHAPES OF INDICATOR SPOT ARE DEPENDENT ON
-
7/31/2019 Condition Mon Oil
35/45
Recommended limits of unused mineral oil fil
power transformer
Property Highest voltage equipmen
-
7/31/2019 Condition Mon Oil
36/45
Water content, ppm, min 20 15
Interfacial tension, N/m, min 35 35
Dielectric Dissipation Factor
@ 90 C, 40-60 Hz, max0.015 0.015
Resistivity, ohm-cm, min 6 6
Breakdown voltage, kV, min 40 50
Oxidation stability of
uninhibited oil
Neutralisation value,
Mg.KOH/g, min
Sludge (% by Mass), max
oxidation stability of inhibited
oil - induction period
0.4 0.4
0.1 0.1
Similar values before fill
-
7/31/2019 Condition Mon Oil
37/45
-
7/31/2019 Condition Mon Oil
38/45
-
7/31/2019 Condition Mon Oil
39/45
-
7/31/2019 Condition Mon Oil
40/45
-
7/31/2019 Condition Mon Oil
41/45
-
7/31/2019 Condition Mon Oil
42/45
-
7/31/2019 Condition Mon Oil
43/45
-
7/31/2019 Condition Mon Oil
44/45
-
7/31/2019 Condition Mon Oil
45/45