Transformer OnTransformer On--Line Line MonitoringMonitoring

Rowland JamesRowland James

EntergyEntergyNovember 8, 2004November 8, 2004

ProloguePrologue

Why OnWhy On--Line Monitoring & Diagnostics?Line Monitoring & Diagnostics?

Aging and Failure ModesAging and Failure Modes

Failure StatisticsFailure Statistics

Current Monitoring & Analysis MethodsCurrent Monitoring & Analysis Methods

Why OnWhy On--Line Monitoring & Diagnostics?Line Monitoring & Diagnostics?

Aging Fleet Aging Fleet Reducing Probability of Catastrophic FailureReducing Probability of Catastrophic Failure

Reducing NonReducing Non--Catastrophic Unscheduled OutagesCatastrophic Unscheduled Outages

Deferring Capital Costs of Upgrades/ReplacementsDeferring Capital Costs of Upgrades/ReplacementsExtending Overall Life of EquipmentExtending Overall Life of Equipment

Allowing ShortAllowing Short--Term OverloadingTerm Overloading

Reducing O&M CostsReducing O&M Costs

Insulating FluidInsulating Fluid2 Main Purposes:2 Main Purposes:

Dielectric InsulatorDielectric Insulator

Thermal TransferThermal Transfer

Additional Benefit:Additional Benefit:Transport Vehicle for Telltale Gases & Acoustical SignalsTransport Vehicle for Telltale Gases & Acoustical Signals

Combustible Gases are Released under Very Specific Combustible Gases are Released under Very Specific CircumstancesCircumstances

Transformer AgingTransformer Aging

Winding Insulation (i.e., Paper/Cellulose) Winding Insulation (i.e., Paper/Cellulose) The One Component with NonThe One Component with Non--Reversible Life Reversible Life Characteristic Characteristic –– It Will Age.It Will Age.

Factors Affecting Life of Cellulose:Factors Affecting Life of Cellulose:HeatHeat

Paper Moisture (Main Source of Degradation)Paper Moisture (Main Source of Degradation)

Oxygen Content of OilOxygen Content of Oil

Transformer Aging (contd.)Transformer Aging (contd.)

Failure StatisticsFailure StatisticsOutage Rates Generally RisingOutage Rates Generally Rising

Approximately 1.45% Prior to 1990Approximately 1.45% Prior to 1990

Approximately 5.5% After 1990Approximately 5.5% After 1990

Costs of Outages Due to RepairsCosts of Outages Due to RepairsMajor FailuresMajor Failures

$1.5 million After Event Vs. $200k+ via Early Detection$1.5 million After Event Vs. $200k+ via Early Detection

Catastrophic FailuresCatastrophic Failures$5+ million Post Event Vs. $200k+ via Early Detection$5+ million Post Event Vs. $200k+ via Early Detection

Current Monitoring Methods Current Monitoring Methods

ThermalThermal

Dissolved Gas Analysis (DGA)Dissolved Gas Analysis (DGA)ManualManual

OnOn--Line Line

Moisture DetectionMoisture Detection

Current Monitoring Methods ( contd.)Current Monitoring Methods ( contd.)

BushingsBushings

LTC Oil Dielectric StrengthLTC Oil Dielectric Strength

Acoustical AnalysisAcoustical Analysis

Other Traditional MethodsOther Traditional Methods

ThermalThermal

Top & Bottom OilTop & Bottom Oil

Winding Temperature (Direct, Calculated or Winding Temperature (Direct, Calculated or Simulated)Simulated)

Ambient Temperature (remote from any heat Ambient Temperature (remote from any heat source in the substation)source in the substation)

Control Cabinet TemperatureControl Cabinet Temperature

Tank Temperature (surface mount)Tank Temperature (surface mount)

Dissolved Gas AnalysisDissolved Gas AnalysisDGA DGA –– Biggest Bang for the Buck!Biggest Bang for the Buck!

InexpensiveInexpensive

Very Sensitive to Changes in Main TankVery Sensitive to Changes in Main Tank

Can be applied to LTC’s and OCB’sCan be applied to LTC’s and OCB’s

Extremely ReliableExtremely Reliable

Trendable Trendable

Dissolved Gas Analysis (contd.)Dissolved Gas Analysis (contd.)

New TechnologiesNew TechnologiesOn Line DGA/Fault Gas On Line DGA/Fault Gas

On Line Hydrogen & Moisture On Line Hydrogen & Moisture

Some Suppliers GESome Suppliers GE--Hydran, Morgan & Hydran, Morgan & SchaeferSchaefer

BushingsBushings

Manual Power Factor measurements (Doble, Manual Power Factor measurements (Doble, Vanguard, Omicron, Biddle, etc.)Vanguard, Omicron, Biddle, etc.)

Capacitance tap bushing monitor. (Doble Capacitance tap bushing monitor. (Doble continuous measurement, others may require continuous measurement, others may require site visits in order to download data. (Cutler site visits in order to download data. (Cutler Hammer, ZTZ)Hammer, ZTZ)

LTC/TCULLTC/TCUL

Dielectric Strength Tester (onDielectric Strength Tester (on--line Developed line Developed by MIT & Entergy)by MIT & Entergy)

Contact Wear Indicator (EPRI R&D project)Contact Wear Indicator (EPRI R&D project)

DGA for LTCDGA for LTC

Infrared MonitoringInfrared Monitoring

Differential Temperature MonitoringDifferential Temperature Monitoring

Fans & PumpsFans & Pumps

Pumps Pumps –– apply bearing wear indicators to apply bearing wear indicators to pump. Monitor voltage, current & flow.pump. Monitor voltage, current & flow.

Fans Fans -- Monitor voltage, current and/or Monitor voltage, current and/or employ air flow indicator.employ air flow indicator.

Cycle lead and lag for fans (back up with Cycle lead and lag for fans (back up with mechanical control)mechanical control)

NonNon--monitoring issue but important for fans monitoring issue but important for fans –– totally enclose fan cages to prevent bird totally enclose fan cages to prevent bird cages.cages.

Voltage & CurrentVoltage & Current

Use for Dynamic loading and Loss of life Use for Dynamic loading and Loss of life calculationscalculations

Current Current –– Clip on CT’s (1:1) but hard wired Clip on CT’s (1:1) but hard wired CT’s more reliable (if transient measurements CT’s more reliable (if transient measurements desired)desired)

Voltage Voltage –– use existing PT’s, BPT’s or CCVT’suse existing PT’s, BPT’s or CCVT’s

Partial Discharge DetectionPartial Discharge Detection

Acoustic Acoustic –– short term testing (portable short term testing (portable ––magnetic accelerometers). Use for magnetic accelerometers). Use for benchmarking and trouble investigations benchmarking and trouble investigations (gassing also detectable)(gassing also detectable)

Permanent installations for desired Permanent installations for desired continuous monitoring (bushing mounted)continuous monitoring (bushing mounted)

Monitoring LevelsMonitoring Levels

11

Generator Step Up’s (base load) & Generator Step Up’s (base load) & Transmission Autotransformers, Transmission Autotransformers,

Criticality Criticality -- HighHigh

Maximum Maximum MonitoringMonitoring

Monitoring Levels (contd.)Monitoring Levels (contd.)

2 2

High MVA, Peaking GSU’sHigh MVA, Peaking GSU’s

Criticality Criticality –– ModerateModerate

Medium MonitoringMedium Monitoring

Monitoring Levels (contd.)Monitoring Levels (contd.)

3 3

Specific casesSpecific cases

Critical loads & Processes such as Critical loads & Processes such as

Oil Refineries, Chemical Plants,Oil Refineries, Chemical Plants,

Medical Facilities, Military InstallationsMedical Facilities, Military Installations

Maximum to Medium MonitoringMaximum to Medium Monitoring

Monitoring Levels (contd.)Monitoring Levels (contd.)

4 4

Normal use age Normal use age

Conventional MonitoringConventional Monitoring

New vs. RetrofitNew vs. Retrofit

New New –– Factory installed ( should be covered Factory installed ( should be covered in purchase specification). Additional thermal in purchase specification). Additional thermal wells, etc.wells, etc.

Retrofit Retrofit –– Additional thermal wells (add to Additional thermal wells (add to radiators?); magnetic RTD’sradiators?); magnetic RTD’s

Pumps Pumps –– Replace GER/Harley/Cardinal Replace GER/Harley/Cardinal

Data Handling & StorageData Handling & Storage

Information vs. dataInformation vs. dataExpert System Expert System –– Local and RemoteLocal and Remote

CommunicationsCommunicationsLocal Local --LAN, Fiber Optics, Twisted PairLAN, Fiber Optics, Twisted Pair

Remote Remote –– WAN, Fiber Optics, Twisted Pair, WAN, Fiber Optics, Twisted Pair, Satellite Satellite

HMI local and/or RemoteHMI local and/or Remote

ConclusionConclusionWhy Transformer Why Transformer

OnOn--Line Monitoring?Line Monitoring?