asset management through transformer monitoring.ppt · • transformer materials • thermal...
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Copyright © SEL 2017
Asset Management through Transformer Monitoring
Ed Atienza
Overview
• Transformer materials
• Thermal aspects of transformer life
• IEEE C57.91 thermal monitoring
• Through-fault monitoring
• Monitoring Using the SEL-2414
Transformer Materials
• Core steel
• Copper or aluminum coils
• Paper insulation
• Mineral oil insulating liquid
• Steel tank
• Bushings
Transformer MaterialsCore Steel
Transformer MaterialsCoils and Insulation
• Copper or aluminum coils
• Paper insulation
Other Transformer MaterialsBushings and Steel Tank
Transformer Failure Statistics1983 to 1988
• Core
• Winding
• Tap changer
• Bushing
• Terminal board
• Miscellaneous
1%
37%
22%
11%
3%
26%
Factors Affecting WindingInsulation Life
• Water – controlled by oil treatment
• Oxygen – controlled by oil treatment
• Heat – controlled by operating personnel♦ Chemical reaction rate doubles for
each 5° to 10°C increase in temperature (Arrhenius’ theory)
♦ Loss of degrees of polymerization reduces insulation efficiency
Internal CoolingMedium
Circulation Mechanism
External Cooling Medium
Circulation Mechanism
O = Oil (fire point < 300°C)
N = Natural convection A = Air N = Natural
convection
K = Insulatingliquid (fire point
> 300°C)
F = Forced circulation W = Water F = Forced
circulation
L = Insulating liquid (fire point not measurable)
D = Directed with force NA NA
Transformer Cooling Classes
i.e., ONAN, ONAF, and ODAF
Average Winding Temperature
• Calculable with winding resistance measurement
• Not directly used for transformer life calculations
2I
Winding Hot-Spot Temperature
• Calculated with thermal model
• Measured with fiber-optic probe
• Difficult to correctly locate
• Directly used for transformer life calculations
Winding Hot-Spot Temperature Graphic
2I
How Thermal Monitoring Works
Uses formulas from IEEE C57.91 to calculate transformer temperatures
Transformer Thermal Model
Thermal Model Responseto a Load Step Change
Insulation Aging
• Winding hottest-spot temperature above the limit damages insulation
• One hour at 120°C ages the insulation the equivalent of 2.7 hours at 110°C
• Thermal model calculates insulation aging and accumulated transformer loss of life
How Old Is Your Transformer, Thermally?• Typical loading
♦ Very light
♦ Cycles daily
♦ Fully loaded
♦ Overloaded
• Average ambient temperature♦ Cold
♦ Moderate
♦ Hot
• Type of cooling system♦ Fans and oil pumps
♦ Two-stage fans
♦ Single-stage fans
♦ Passive only
Purpose of Thermal Model
• Real-time loading capability
• Long-term loss-of-life tracking
Single Tank With Three-Phase WindingsETHERM:=1
Three Tanks With Single-Phase WindingsETHERM:=3
Single Tank With Three Sets of WindingsETHERM:=W
Hourly Thermal Reports
=>>THE H <Enter>SEL-2414 Date: 03/31/2009 Time: 10:00:00DEVICETransformer 1
Ambient Calc Measure LoadDate Time Temp Top-Oil Top Oil Hot Spot Current FAA03/31/2009 0800 15.0 58.4 59.9 94.6 0.96 0.9003/31/2009 0900 15.0 58.4 59.9 94.6 0.96 0.90Transformer 2
Ambient Calc Measure LoadDate Time Temp Top-Oil Top Oil Hot Spot Current FAA03/31/2009 0800 15.0 59.2 60.1 95.0 1.00 0.9503/31/2009 0900 15.0 59.2 60.1 95.0 1.00 0.95Transformer 3
Ambient Calc Measure LoadDate Time Temp Top-Oil Top Oil Hot Spot Current FAA03/31/2009 0800 15.0 61.6 61.0 95.4 1.01 0.9603/31/2009 0900 15.0 61.6 61.0 95.4 1.01 0.96=>>
Daily Thermal Reports
=>THE D <Enter>SEL-2414 Date: 12/21/2012 Time: 00:37:34DEVICETransformer 1
Max Max Max Max Max MaxDate Time AMBT TOILC TOILM LOAD HS FAA RLOL TLOL12/20/2012 0000 24.5 57.3 59.9 0.91 109.6 0.99 0.014 2.34512/21/2012 0000 24.5 58.4 60.9 0.95 110.8 1.10 0.015 2.360Transformer 2
Max Max Max Max Max MaxDate Time AMBT TOILC TOILM LOAD HS FAA RLOL TLOL12/20/2012 0000 24.5 57.3 59.9 0.91 109.6 0.99 0.014 2.34512/21/2012 0000 24.5 58.4 60.9 0.95 110.8 1.10 0.015 2.360Transformer 3
Max Max Max Max Max MaxDate Time AMBT TOILC TOILM LOAD HS FAA RLOL TLOL12/20/2012 0000 24.5 57.3 59.9 0.91 109.6 0.99 0.014 2.34512/21/2012 0000 24.5 58.4 60.9 0.95 110.8 1.10 0.015 2.360=>>
What Is a Through Fault?
Through-Fault Monitor – Why?
• Thermal stress – low-magnitude faults
• Mechanical stress – high-magnitude faults
Transformer Through-Fault Capability
• Through faults cause thermal and mechanical stresses
• Mechanical effects are cumulative
• Extent of damage depends on:♦ Current magnitude
♦ Fault duration
♦ Total number of faults
Transformer Categories Per IEEE C57.12.00
Category Single‐Phase kVA Three‐Phase kVA
I 5 to 500 15 to 500
II 501 to 1,667 501 to 5,000
III 1,668 to 10,000 5,001 to 30,000
IV Above 10,000 Above 30,000
Transformer Through-Fault Capability Curves (IEEE C57.12.00)
• Define through-fault withstand capability
• Apply to transformers designed per IEEE C57.12.00
• Six curves:♦ One each for Category I and IV transformers
♦ Two each for Category II and III transformers (frequent and infrequent faults)
1,668–10,000 kVA 1-Phase5,001–30,000 kVA 3-Phase
Source: IEEE C57.12.00-2010, IEEE Standard for General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers
Category III
Category IV
Above 10,000 kVA 1-PhaseAbove 30,000 kVA 3-Phase
Source: IEEE C57.12.00-2010, IEEE Standard for General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers
Through-Fault Monitoring
• Monitor measures and records through-fault currents
• Estimates I2t values per phase and provides alarm
• Helps finding transformer problems and prioritizing maintenance
• Helps detecting high external fault activity
Combined Effect of Thermal and Through-Fault Stresses
Through-Fault Settings
Through-Fault Events
=>>TFE
SEL-2414 Date: 02/25/2013 Time: 13:53:39DEVICE
Winding ETotal Number of Transformer Through Faults: 16Total Number of A Phase Through Faults: 8Total Number of B Phase Through Faults: 8Total Number of C Phase Through Faults: 8
Total Accumulated Percentage of Through Fault Capability:A-Phase B-Phase C-Phase59.81 38.56 35.64
Through Fault Alarm: 1 0 0
Last Reset: 02/25/2013 13:49:13
Through-Fault Events
# DATE TIME Duration IA IB IC A B C Alarm(seconds) (max primary kA) (Increment %)
1 02/25/2013 13:53:34.505 1.013 0.00 0.00 32.15 0.00 0.00 4.35 A2 02/25/2013 13:53:32.500 1.013 0.00 34.80 0.00 0.00 5.07 0.00 A3 02/25/2013 13:53:29.500 2.017 43.41 0.00 0.00 15.84 0.00 0.00 A4 02/25/2013 13:53:27.999 0.521 43.40 43.39 43.85 3.97 3.97 3.97 5 02/25/2013 13:53:10.702 1.013 0.00 0.00 32.16 0.00 0.00 4.35 6 02/25/2013 13:53:08.697 1.013 0.00 34.75 0.00 0.00 5.07 0.00 7 02/25/2013 13:53:05.697 2.017 43.40 0.00 0.00 15.85 0.00 0.00 8 02/25/2013 13:53:04.196 0.521 43.41 43.41 43.70 3.97 3.97 3.97 9 02/25/2013 13:52:24.175 1.013 0.00 0.00 32.15 0.00 0.00 4.35 10 02/25/2013 13:52:22.170 1.017 0.00 34.75 0.00 0.00 5.08 0.00 11 02/25/2013 13:52:20.174 1.013 43.41 0.00 0.00 7.92 0.00 0.00 12 02/25/2013 13:52:18.869 0.321 43.38 43.38 43.40 2.38 2.38 2.38 13 02/25/2013 13:50:23.241 1.013 0.00 0.00 32.35 0.00 0.00 4.35 14 02/25/2013 13:50:21.236 1.017 0.00 34.73 0.00 0.00 5.08 0.00 15 02/25/2013 13:50:19.206 1.042 30.38 0.00 0.00 1.96 0.00 0.00 16 02/25/2013 13:50:17.201 1.021 43.41 43.82 43.40 7.93 7.93 7.92
Through-Fault Monitor Logic
ETHRFLT(Setting)
4.75 • IFULLLOAD
4.5 • IFULLLOAD
IA
–+
–+
S Q
R
1 min
0
Enable 0
10 cyc
10-Cycle Timer
1-Minute Timer
Total Counter
A-Phase Counter
Archive
Start TimeStop Time
Maximum Current Calculation
2RMS _pu
0.25 •100%t(I ) •FREQ
+–
TFLTALATHFLTPU
SEL-2414Transformer Monitoring and Much More
• IEEE C57.91-1995 transformer thermal model
• Through-fault monitoring
• Flexible I/O choices
• Critical reporting and logging
• Extensive ac metering capabilities
• Powerful integration with SCADA
• Simple commissioning tools
Track Important Transformer Quantities
• Ambient temperature
• Top-oil temperature calculations and measurements
• Winding hot-spot temperature
• Per-unit load
• Loss of life
Analog Signal ProfilingVisualize Key Data
Tem
pera
ture
Additional FunctionalityUsing Settings or Design Templates
• Replacement of other devices
• Fan control and monitoring
• Load tap changer (LTC) control
Replace Other Devices
• Oil temperature gauge
• Hot-spot temperature gauge
• 63PR seal-in relays
• Discrete control relays
• Indicator lights and switches
Communications Protocols Single or Dual Ethernet
• Copper and fiber optic
• Modbus TCP
• FTP, Telnet, and Ping
• DNP3 LAN / WAN (optional)
• IEC 61850 (optional)
SEL-2414 Summary
• Communication via front-panel HMI, serial ports, and Ethernet networks
• Transformer monitoring♦ Thermal monitoring
♦ Through-fault monitoring
• Design templates♦ LTC control
♦ Fan control
Questions?