| Date post: | 05-Dec-2014 |
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GAPGAPGAPGAPGAPGAPGAPGAP11111111generator assessment processgenerator assessment processgenerator assessment processgenerator assessment process
a solution to life assessment of large generators
[email protected]@gmail.com
GAPGAPGAPGAP1111 GAPGAPGAPGAP2222
GAPGAPGAPGAP****
GAPGAPGAPGAP4444 GAPGAPGAPGAP3333
GAPGAPGAPGAP****
GAPGAPGAPGAP1111 evaluates the thermal residual
life from experience and theaccumulated data
Optionally diagnosis of faults throughon-line testing - vibration signatureanalysis, current signature analysis andinfrared thermal imaging
MethodologyMethodologyMethodologyMethodology
The methodology employed is estimation ofconsumed life and residual life
Consumed life is estimated by operationalhistory
Residual life is estimated by consumed life,establishment of calculation method forresidual break-down voltage and operationpattern in the future
UnitUnitUnitUnit ConditionConditionConditionCondition
The generator is in operation
InspectionInspectionInspectionInspection &&&& teststeststeststests PerformedPerformedPerformedPerformed
OEM data and specificationOEM data and specification
Operational history
Operational parameters
Thermal profile
Maintenance history
BenefitsBenefitsBenefitsBenefits
Extent of thermal life degradation
Preventive maintenance plan
Schedule for GAP2222, GAP3333 and GAP4444
FinalFinalFinalFinal ReportReportReportReportFinalFinalFinalFinal ReportReportReportReport
Standardized format in electronic form
Photographs of critical areas
Thermal residual life
Analysis and recommendation
ExpectedExpectedExpectedExpected DowntimeDowntimeDowntimeDowntime
Zero days
OptionOptionOptionOption
Vibration severity levelVibration severity level
Vibration signature analysis
Electrical Signature analysis
Infrared thermal imaging
Life AssessmentThermal Life Assessment
Ageing of an Electrical Insulation System
Assessment of Condition and Residual Life Time
Inverse Power Law and Arrhenius Law
Single Stress and Multi Stress Ageing of EIS
Thermal Life AssessmentArrhenius Equation
TTTThermalhermalhermalhermal ElectricalElectricalElectricalElectrical
StressStressStressStress
MechanicalMechanicalMechanicalMechanical AmbientAmbientAmbientAmbient
StressStressStressStress
Thermal Ageing Model
The thermal ageing in insulating materials is complexand the mechanisms vary in different materials andunder different service conditions.To a first approximation, the oxidation process can beexpressed by the Arrhenius rate law.
It is evident that, the higher the temperature, theshorter is the life expectancy of the insulation. TheArrhenius law is the basis of all accelerated ageingtests which are used to estimate the thermal life of awinding and is also used to define the insulationthermal classes
Arrhenius Equation
Dr. Svante August Arrhenius was a Swedish scientist, professor of physics, and the founder of physical chemistry. In 1903, he received the Nobel Prize for
Chemistry for his study of ionic theory
Lr ∝ f (Y, Yo, N, Tmax, Tavg, Tamb)
Lr = Residual thermal life (years)
Y = Operating years
Yo = Equivalent operating years
N = Number of starts/stops
Tmax = Maximum allowable temperature (oC)
Tavg = Average operating temperature (oC)
Tamb = Ambient temperature (oC)
THE R MAL L IF E
C urves plotted at different winding temperature in oC
50
60
70
80
90
100
% L
ife
81859095100
0
10
20
30
40
0 5 10 15 20 25 30 35
x 10000
Hours of Operation
81 85 90 95 100 pres ent
R emaining T hermal L ife vs Winding T emperature
81
8515
20
25
x 1
00
00
Re
am
ain
ing
Lif
e
(No
. o
f h
ou
rs)
90
100
95
0
5
10
80 82 84 86 88 90 92 94 96 98 100
T emperature (deg C )
Re
am
ain
ing
Lif
e
(No
. o
f h
ou
rs)
50
60
70
80
90
100
Residual Thermal Life(%)
Thermal Life Estimation by Arrhenius EquationBHEL 46.25 MVA, 11 KV, 3000 rpm Turbo-generator @ Monnet Ispat, Raipur
presentlife
0
10
20
30
40
0 5
10
15
20
25
30
Residual Thermal Life(%)
Operating Years
residual thermal life present life thermal life
thermal life
40
50
60
70
80
90
100
Residual Thermal Life(%)
GAP Estimation by Arrhenius EquationBHEL 46.25 MVA, 11 KV, 3000 rpm Turbo-generator @ Monnet Ispat, Raipur
0
10
20
30
40
0 5
10
15
20
25
30
Residual Thermal Life(%)
Operating Years
GAP11 GAP21 GAP31 GAP41 GAP12 GAP22 GAP32 GAP42
10987654321
Life Index
10987654321
Thermal Life AssessmentN-Y Map Method
TTTThermalhermalhermalhermal ElectricalElectricalElectricalElectrical
StressStressStressStress
MechanicalMechanicalMechanicalMechanical AmbientAmbientAmbientAmbient
StressStressStressStress
Electrical aging and thermal aging both depend onservice operation in year (Y), and aging due toheating and cooling is proportional to the number ofstarts-stop of a machine (N)
From empirical data based on the insulation systemstudy i.e. the electrical, thermal aging characteristicsand the heating and cooling cycle characteristics, aNY-map is derivedNY-map is derived
From the equation by experimental data, the residualbreakdown strength (%) is as
Vr ∝ f (Y, N, No, Tmax, Tavg, Tamb)
Vr ∝ f (Y, N, No, Tmax, Tavg, Tamb)
Vr= Residual breakdown strength (%)
Y = Operating years
N = Number of starts/stops
No = Equivalent number of starts/stops
Tmax = Maximum allowable temperature (oC)
Tavg = Average operating temperature (oC)
Tamb = Ambient temperature (oC)
65
70
75
80
85
90
Residual Breakdown Strength (%)
Thermal Life Estimation by N-Y MethodBHEL 46.25 MVA, 11 KV, 3000 rpm Turbo-generator @ Monnet Ispat, Raipur
presentlife
thermal life
40
45
50
55
60
0 5 10 15 20 25 30 35 40
Residual Breakdown Strength (%)
Operating Years
Residual Breakdown Strength Minimum Breakdown Strength present life thermal life
thermal life
10987654321
Life Index
10987654321
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