s10 tr-tank rupturetutorial

Investigation Report

Power Transformer Tank Rupture and Mitigation - Current State of Practice and Knowledge

by the Task Force of IEEE Power Transformer Subcommittee

March 09, 2010 Houston, TX.

CONTENT

1.Investigation and Analysis -10 minutes 2.Utility Experience (15 minutes) 3.Manufacturer’s Perspective (25 minutes) 4.PRD (10 minutes)5.Conclusions (10 minutes ) 6.Q&A (5 minutes)

Analysis of Transformer Tank Ruptures

Electric Power Research Institute

Wayne [email protected]

Nick [email protected]

2

Survey On Transformer Rupture

Objectives• Develop an understanding of the tank rupture process

associated with internal faults.• Develop tools, and methods, for evaluating the influence

of tank designs on rupture characteristics

3

Background

• 42 transformer failures (tanks ruptured or deformed without rupture)

• 22 utilities • 10-year period (1980-1990)• 7 transformer manufacturers• Different voltage levels• Different designs: (GSU’s, Auto,

Phase Shifters, etc.)

4

Conclusions

• The arc energy is the critical rupture parameter • Differences in transformer design and application are not major

discriminators in the tank rupture • The fault energy capacity of a tank can be increased by increasing

the tank rupture pressure limit and tank flexibility. – The pressure at which tanks rupture can be increased by local

strengthening of weak points, while the tank flexibility can be increased by replacing large beams with a number of smaller beams (which permit greater deflection at a given stress level).

• Venting to conservators or to auxiliary tanks was not found to be effective for heavy faults (those with arc power greater than 300 MW)

5

Conclusions

• A long arcing time is not necessary for rupture: – About 75% of the cases

occurred with arcing times less than 4.5 cycles.

• Since arc energy is proportional to I2t, where the t is duration in seconds, the parameter which offers the most opportunity for control of the risk of rupture is the magnitude of the current, and specifically, the peak crest value of the first half cycle of the fault current (and the associated X/R of the circuit).

Graph of Tank Deformation Rupture as a function of fault

current and fault duration.

Power Transformer Tank RuptureA Utility's Experience

Marc FoataIEEE Transformers CommitteeHouston, March 2010

22

PresentationPresentation

AssessmentAssessment of the of the riskriskStatisticsStatisticsArc Arc energyenergy

PreventionPrevention of tank ruptureof tank ruptureVentingVentingContainmentContainment

SpecificationSpecification of a Tank pressure of a Tank pressure withstandwithstandrequirementrequirement

33

AssessingAssessing the the riskrisk -- StatisticsStatistics

44


55


66

Arc Arc energyenergy -- 4 MJ4 MJ

77

Arc Arc EnergyEnergy -- 8 MJ8 MJ

88


99


1010

Arc Arc energyenergy vs Damagevs Damage

1111

Arc Arc EnergyEnergy -- CalculationCalculation

I I –– Arc Arc currentcurrent: : EvaluatedEvaluated fromfrom shortshort--circuit circuit levellevelT T –– Fault clearing time: Fault clearing time: DependsDepends mainlymainly on on protectionprotectionV V –– Arc voltage: Arc voltage: VeryVery difficultdifficult to to evaluateevaluate0.9 0.9 –– Factor Factor introducedintroduced for square for square waveformwaveform of Vof V

tIVEarc 9.0=

1212

Arc Arc EnergyEnergy -- RecordingsRecordingsUnité Support et analyses - DESTT

A

205 210 215 220 225 230 235 240 245 250 255(ms rel. à 05:34:32.2870)

-80

-60

-40

-20

0

20

40

60

80

100

(kV

)

E BN TT MAIS MICOUA E BN L-7019 MICOUA E BN L-7011 MICOUA E BN L-7027 MICOUA

2008-09-12 05:34:32.499 MICOUA 735-02 TENSION RÉSIDUELLE DÉFAUT TRANSFO T8-B

205 210 215 220 225 230 235 240 245 250 255(ms rel. à 05:34:32.2870)

-1 0 1 2 3 4 5 6 7 8 9

101112

(MJo

ules

)

ÉNTERGIE TOTALE (TT MAIS)ÉNTERGIE TOTALE (TTC 7019)ÉNTERGIE TOTALE (TTC 7011)ÉNTERGIE TOTALE (TTC 7027)

2008-09-12 05:34:32.499 MICOUA 735-02 ESTIMÉ DE L'ÉNERGIE TOTALE DANS LE DÉFAUT TRANSFO T8-B

190 200 210 220 230 240 250 260 270(ms rel. à 05:34:32.2870)

-20000

-15000

-10000

-5000

0

5000

10000

15000

20000(A

)

COURANTS CÔTÉ 735 kVCOURANTS APROX. CÔTÉ 315 kV

2008-09-12 05:34:32.499 MICOUA 735-02 COURANTS DE DÉFAUT TRANSFO T8-B

Lundi 15 Septembre, 2008\\VECTEUR\DONNEES\PARTAGE\@AUTOMATISMES\COMPORTEMENT\RAPPORT\RAPP_2008\TOSC_ANA\20080912_053432499_ENERGIE_T8-B_MICOUA.TOS

1313

Arc Arc EnergyEnergy -- EvaluationEvaluation of Arc of Arc VoltageVoltage

6060--100 V/cm range 100 V/cm range isis oftenoften referredreferredFor 40 kV, For 40 kV, thisthis meansmeans an arc an arc lengthlength of of more more thanthan 4 m !!4 m !!

1414

Arc Arc EnergyEnergy -- Pressure Pressure EffectEffect

Constant 55 V/cmConstant 55 V/cmL L isis arc arc lengthlength (m)(m)P P isis absoluteabsolute pressure (pressure (atmatm))Pressure in the Pressure in the gasgas bubblebubble at arc ignition at arc ignition cancan reachreach extremelyextremely highhigh valuesvalues

PLV 55=

1515

PreventionPrevention of tank rupture of tank rupture ––VentingVenting SimulationsSimulations

1616

PreventionPrevention of tank rupture of tank rupture ––VentingVenting SimulationsSimulations

1717

PreventionPrevention of tank rupture of tank rupture –– VentedVentedvs Nonvs Non--ventedvented ExampleExample

1818

PreventionPrevention of tank rupture of tank rupture ––Conclusions on Conclusions on ventingventing

Pressure Pressure reductionreduction fromfrom a single 25 cm a single 25 cm aperture aperture isis lowlow and and becomesbecomes negligiblenegligiblewhenwhen the arc the arc isis more more thanthan 1 1 metermeter awayaway..An effective pressure An effective pressure ventingventing strategystrategywouldwould requirerequire eithereither a a veryvery large large ventingventingductduct or or numerousnumerous smallsmall apertures in the apertures in the close close vicinityvicinity of the arc.of the arc.

1919

PreventionPrevention of tank rupture of tank rupture --ContainmentContainment

2020

PreventionPrevention of tank rupture of tank rupture --ContainmentContainment

PresentPresent design design cancan containcontain up to 10 MJ up to 10 MJ for the for the largestlargest tanks (735 kV)tanks (735 kV)More More resistantresistant tank design tank design cancan bebeachievedachievedNeedNeed to to implementimplement specificationsspecifications with with minimum minimum energyenergy requirementrequirement to to meetmeet..EnergyEnergy requirementrequirement willwill bebe a compromise a compromise betweenbetween the the feasibilityfeasibility and the and the likelihoodlikelihood..

2121

New New SpecificationSpecification -- PhilosophyPhilosophyPriorityPriority isis givengiven to the protection of the to the protection of the workersworkersWorstWorst energyenergy levelslevels maymay not not alwaysalways bebecontainablecontainable by the tankby the tankFirst rupture point must First rupture point must bebe the the covercoverRequiredRequired calculationcalculation toolstools must must bebeaccessible to transformer designersaccessible to transformer designersMust Must taketake intointo accountaccount the the highlyhighly dynamicdynamicphenomenaphenomena involvedinvolvedMust Must bebe easilyeasily verifiedverified

2222

New New specificationspecification -- FormulaFormula

Ps Ps –– CalculatedCalculated tank pressure tank pressure withstandwithstandF F –– DynamicDynamic (time & location) amplification(time & location) amplificationE E –– Fault Fault energyenergy levellevel to to withstandwithstandK K –– Arc Arc energyenergy conversion factorconversion factorC C –– Tank expansion coefficientTank expansion coefficient

⎥⎦

⎤⎢⎣

⎡−+= 50

10041100

CkE

s FP

2323

New New specificationsspecifications –– DynamicDynamicfactorfactor

Time Time relatedrelated dynamicdynamic factor (pressure and factor (pressure and deformationdeformation))ProximityProximity relatedrelated dynamicdynamic factorfactorTakesTakes intointo accountaccount tank volumetank volume

1

1,5

2

2,5

3

0 20 40 60 80 100 120 140 160 180 200

C/V (x 10 -5 kPa-1)

F

2424

New New specificationspecification : : HydroHydro--Québec'sQuébec'sEnergyEnergy ContainmentContainment RequirementsRequirements

Voltage Class Arc Energy

2525

New New specificationspecification -- ImplementationImplementation

All transformer All transformer supplierssuppliers sincesince 1992 have 1992 have shownshownadequateadequate tank tank withstandwithstand calculationcalculation capabilitiescapabilities..SinceSince implementingimplementing energyenergy levellevel requirementsrequirements(2006), (2006), manufacturersmanufacturers have been have been forcedforced to to improveimprove theirtheir tank design.tank design.DetailedDetailed analysisanalysis by a by a numbernumber of of manufacturersmanufacturersconfirmedconfirmed thatthat all the all the specifiedspecified energyenergyrequirementsrequirements cancan bebe met.met.

Transformer Tanks - Some Factors Related to Rupture

A Manufacturers Perspective

IEEE Transformers Committee Houston, March 9, 2010

by Bill Darovny, P.Eng.Siemens Canada

Facts about Liquid Filled Transformer Tanks

• C57.12.00 and C57.12.10 define the operating pressures for transformer tanks– full vacuum = -101.4 kPa (-14.7 psig)– pressure 25% above the normal operating

pressure

• Transformer tanks are not pressure vessels– are not required to be designed to the ASME

Boiler and Pressure Vessel Code.• ASME code is mandatory when operating

pressure exceeds 2 atmospheres (203 kPa).

Facts about Liquid Filled Transformer Tanks

• C57.12.10 requires a pressure relief device to be mounted on the tank cover – Typically activate at 34.5 to 69 kPa (5 to 10 psig)

• Most rectangular tanks will sustain internal pressures of 140 to 210 kPa (20 to 30 psig) before rupture

• A tank on its own cannot be made strong enough to resist all magnitudes of internal pressure

Transformers have been saved from rupture by common protection devices

• Pressure Relief Devices• Gas Detector Relays• Rapid Pressure Rise Relays• Real time Gas Monitors

Provided the alarm signals are quickly recognized and the transformer is

de-energized

Pressure Relief Device in Action

Not Every Tank Rupture Results in a FireUnit gassing, GDR alarmed, long delay in response to alarm,

ambient -30°C, reaction force to rupture shifted unit on the pad.

Some Units Burn After Tank Rupture- 750 MVA 500kV

Same Rating Different Supplier

The Location Where a Tank will Rupture is a Function of:

1. the rate of change of the pressure increaseSlow rate:• Pressure has time to distribute throughout the tank

Fast rate:• Results in a pressure build-up at the source

2. the co-ordinates of the pressure source inside the tank

3. the closest weak spot to those co-ordinates

Slow Rate of Pressure Increase- Failed at 2 locations on the Cover- Tensile end reactions tore the welds at the ends of the stiffeners- Cover end angle rotated and the weld to tank flange cracked

Moderate Rate of Pressure Increase

• Tank failed at the cover joint

• Some stiffeners on the tank wall were permanently deformed

• There were no cracks in the oil containment welds in the tank body

Rapid Rate of Pressure Increase

• Co-ordinates of pressure source was about 1/3 tank height

• Wall plate fracture started at the corner welds and ran almost full height of the tank

• Tank wall to bottom weld joint also failed

Rapid Rate of Pressure Increase

• Cover weld did not fail

• Tank failed at the high stress points in welds at the tank corners and wall penetrations then propagated through the wall plates

• Unit was returned to the factory and rebuilt

Weakest Points of a Rectangular Tank

• Main cover to tank wall flange - weld joint

• Tank wall corners - weld joint

• Tank wall to base plate - weld joint

• High stress points at throats and large penetrations through the tank plates

• High stress points at ends of stiffeners where the end reaction force is transmitted to the tank plate

Main Cover to Tank Wall Flange Mode of Weld Failure

Typical Cover Welded Joint

Upward and outward forces due to internal pressures

Stress is concentrated at the weakest point - the root of the weld.

Weld crack progresses outward from the root

Typical Rectangular Tank Corner Joints

Stresses are on the face of the weld.

The face of the weld is stronger than the root of the weld.

Adding corner gussets will reinforce this joint

Cylindrical Tanks are Inherently Stronger than Rectangular Tanks

• 110MVAR 735 kV shunt reactor

• The tank wall is stressed in hoop tension

• Typically the cylinder walls can sustain pressures > 350 kPa (50 psig)

• Weakest point is the cover weld

Design to Help Reduce Tank Rupture

• Design in service systems to detect faults early & de-energize quickly

• Use detection & relief accessories– Real time gas monitors– Gas detector relays - ensure gas collection

system / piping functions as intended – Rapid pressure relays– Pressure relief devices

• To be effective, relief devices must be located close to the pressure source

• Standard size relief devices may not prevent all tank ruptures

Design to Help Reduce Tank Rupture

• The best location for a tank to fail is at the welded cover joint as this will minimize fluid loss

• Strengthen the tank below the cover joint– Reinforce tank corners and wall to bottom joints

with plates / gussets

– Distribute stiffener end reaction forces with reinforcements or by connecting to stiffeners on adjacent walls

– Reinforce around wall penetrations to reduce the high stress points

Transformer Tank Rupture and Mitigation Transformer Tank Rupture and Mitigation TutorialTutorial

March 9, 2010March 9, 2010

Mitigation Research and Example Techniques

Presented by Craig SwindermanMitsubishi Electric Power Products, Inc.

Research on Transformer Tank Rupture Research on Transformer Tank Rupture MitigationMitigation

• Joint research performed in the mid-1980’s by three large Electric Utilities in Japan, Tokyo University, and several transformer manufacturers.

• Goal was to study ways of reducing the risk of transformer tank explosion in urban substations/ underground substations.

• Full scale model testing performed.

• Arc energies calculated and gas generation rate observed.

• Pressure rise models developed.

• Tank construction countermeasures developed.

Summary of ResearchSummary of Research

Internal Pressure Increase

Tank Explosion

Tank Explosion Tank Explosion ProcessProcess

Arc Test in Oil Tank

Pressure Rise Test

using Full Scale Tx

Verification Verification TestsTests

Study Process for Internal FaultStudy Process for Internal Fault

Estimation of Fault Condition① Arc Current ② Arc Voltage ③ Time ④ Dissolved Gas Generation Volume

Pressure Rise AnalysisDynamic Analysis considering Oil Motion

Comparison between Internal Pressure and Tank Strength

Countermeasure① Tank Strength Improvement ② Protection Relay Improvement

③ System Improvement ④ Pressure Restrained Structure

Internal FaultDissolved Gas

Generation

Internal Pressure

> Tank Strength

Dynamics of Internal Fault (1)Dynamics of Internal Fault (1)

Arc Test in Oil TankArc Test in Oil Tank

Arc Current : 1.3 to 40.9 kA

Time : 3Cycle (0.05sec)Arc Energy : 0.11 to 2.64 MJGap Length : 100 to 300 mm

Oil

Electrode

Arc100

1000

10000

10 100 1000Arc Length (mm)

Arc

Volta

ge (V

)

Gas Volume

0.01

0.1

1

0.1 1 10Arc Energy (MJ)

Gas

Vol

ume

(m3)

*Reference – T. KAWAMURA, M. UEDA, K. ANDO, Y. MAEDA, Y. ABIRU, M. WATANABE, K. MORITSU “Prevention of Tank Rupture Due to Internal Fault of Oil Filled Transformers”, CIGRE, 12-02, 1988.

Dynamics of Internal Fault (2)Dynamics of Internal Fault (2)Pressure Rise Test using Full Scale model for verifying pressure risePressure Rise Test using Full Scale model for verifying pressure rise

Combustion Container

Gas Outlet

(Φ12*72)

Cartridge increment(Max.7500g)

Φ300,L570Upper Tank

Middle TankLower Tank

Transformer : 275kV 300MVAArc Energy : 142,000kW、

Time : 80msec(Single Line-Ground Fault at Upper Tank)

- Pressure rise at internal fault can be simulated by powder combustion, considering nozzle area of container and powder amount.

- Dead space (steel tank) was set for simulating internal parts(Core,Coil).in the tested tank.

Pres

sure

Pres

sure

Pres

sure

Time

Time

Time

Middle Tank

Upper Tank

Measured ResultsAnalytical Results

Lower Tank


Results of AnalysisResults of Analysis• Decomposed gas generation calculated to be around

0.5L/kW sec for larger 275 kV class transformers at HV lead.*

• Dynamic oscillation of fault pressure wave (kinetic energy) has a considerable influence on the pressure rise. (Dynamic Load Factor approx. 1.3 was recommended)*

• Tank expansion characteristics and tank strength are important in determining the transformer’s capability to resist rupture.

• Reinforcements can be made at the joining flange between the tank and cover (or flange between upper and lower tank for shell-form) to significantly improve the tank strength against rupture.


Example of Tank Strength ImprovementExample of Tank Strength Improvement

Alleviation of Stress Concentration

Improvement of Connecting Part Strength by Tie Reinforcement

Conventional Type Improved Type

Connecting Part

• Diaphragm type Conservator Tanks can be used as effective pressure reducing space if the connection duct to the main tank is short, the cross sectional area of the duct is large (approx. 1.4 m dia.), and the air space in the conservator diaphragm is adequate

Pressure Reducing SpacePressure Reducing Space

•Tests on 300 MVA, 230 kV units have verified ability to withstand 15,000 MVA short circuit capacity without rupture of the tank.•Still requires operation of protective relays and circuit breakers to clear fault within approx. 60 - 80 ms.

Transformer main tank

Conservator TankDiaphragm (bladder)

Connection duct

Gas Insulated Power TransformersGas Insulated Power Transformers

•Use SF6 Gas as the insulating and cooling medium instead of insulating oil.

•First units produced in 1967.

•Several thousand units of various sizes now in service worldwide, several manufacturers.

•Transformer applications: From Distribution class units up to 400 MVA, 345 kV ratings.

•Primarily used in substations located in urban areas (including inside buildings, underground) due to safety benefits.

Features of Gas Insulated TransformersFeatures of Gas Insulated Transformers

• Use SF6 Gas as insulating and cooling medium, instead of oil.

• Typically use special internal insulation materials such as plastics, special paper, and pressboard.

• SF6 has excellent dielectric properties, but not as good for heat transfer.

Benefit of Gas Insulated TransformersBenefit of Gas Insulated Transformers

0

20

40

60

80

100

0 0. 2 0. 4 0. 6 0. 8 1

0

20

40

60

80

100

0 0. 2 0. 4 0. 6 0. 8 1

Tank Strength

Oil-Immersed Transformer

Gas Insulated Transformer

Fault Time (sec)

Pres

sure

Ris

e (%

)SF6 Gas Insulation: non-flammable, compressible gas

Pressure rise during an internal fault is slower than oil-immersed (non- compressible fluid), thus SF6 gas reduces the chances of tank explosion

15MVA, Three phase, 50Hz, Continuous Rating,Core-Form,Forced-Gas Natual Air,with On-Load Tap ChangerGNAN/GFAN

H.V. 64.5kV +10/-10% StarL.V. 6.6kV Delta

For underground substation beneath office building

Application ExampleApplication Example

Transformer Tank Rupture and Mitigation - March 9, 2010 J.Herz,

Qualitrol

A VERY BRIEF HISTORY:A VERY BRIEF HISTORY:

PRESSURE RELIEF DEVICES PRESSURE RELIEF DEVICES (PRDs) AND THEIR USE ON (PRDs) AND THEIR USE ON POWER AND DISTRIBUTION POWER AND DISTRIBUTION TRANSFORMERSTRANSFORMERS

BEFOREBEFORE

THERE WERE RETHERE WERE RE--SEALABLE PRDsSEALABLE PRDs……

Rupture DiscsRupture Discs

GOOSENECK CAN ADD TO BACK PRESSUREGOOSENECK CAN ADD TO BACK PRESSUREHAD TO BE REPLACED AFTER OPERATION HAD TO BE REPLACED AFTER OPERATION -- LEFT LEFT THE TRANSFORMER OPEN TO ATMOSPHERIC THE TRANSFORMER OPEN TO ATMOSPHERIC MOISTURE IN THE INTERIMMOISTURE IN THE INTERIMTYPICALLY WITH NO ALARMTYPICALLY WITH NO ALARM

More RecentlyMore RecentlyTHEY HAVE BEEN USED IN MULTIPLE SETS ALONG THEY HAVE BEEN USED IN MULTIPLE SETS ALONG THE TOP AND BOTTOM OF A SINGLE TRANSFORMER THE TOP AND BOTTOM OF A SINGLE TRANSFORMER TO MAXIMIZE THE PRESSURE RELIEF AREA AND TO TO MAXIMIZE THE PRESSURE RELIEF AREA AND TO BE LOCATED AS CLOSE AS POSSIBLE TO ANY BE LOCATED AS CLOSE AS POSSIBLE TO ANY POTENTIAL FAULT LOCATION. POTENTIAL FAULT LOCATION. THEY ARE THE RELIEF MECHANISM FOR THEY ARE THE RELIEF MECHANISM FOR COMBINATION PRESSURE RELIEF/FIRE COMBINATION PRESSURE RELIEF/FIRE SUPPRESSION SYSTEMSSUPPRESSION SYSTEMS

THERE WERE SEVERAL DIFFERENT THERE WERE SEVERAL DIFFERENT DESIGN APPROACHES TO REDESIGN APPROACHES TO RE--SEALING SEALING PRDs MADE BY VARIOUS PRDs MADE BY VARIOUS MANUFACTURERS MANUFACTURERS

IN THE LATE 1950IN THE LATE 1950’’s THE INDUSTRY s THE INDUSTRY SETTLED OVERWHELMINGLY ON ONE SETTLED OVERWHELMINGLY ON ONE DESIGN.DESIGN.

THE DESIGN IS STILL IN FREQUENT THE DESIGN IS STILL IN FREQUENT USE TODAY. IT OFFERS SIMPLICITY USE TODAY. IT OFFERS SIMPLICITY AND DURABILITY IN ADDITION TO AND DURABILITY IN ADDITION TO RERE--SEALABILITY. SEALABILITY.

REFINEMENTS SINCE HAVE TO DO REFINEMENTS SINCE HAVE TO DO WITH IMPROVING THE SEAL, WITH IMPROVING THE SEAL, SHIELDING AND PROTECTION, SHIELDING AND PROTECTION, SWITCH CAPACITY, CORROSION SWITCH CAPACITY, CORROSION RESISTANCE, ETCRESISTANCE, ETC

WHEN OPERATING PRESSURE IS REACHED, TOP SEAL OPENS WHILE SIDE SEAL REMAINS BRIEFLY CLOSED

WITH OPERATING PRESSURE ACTING ON THE LARGER AREA CIRCUMSCRIBED BY THE SIDE SEAL, THE SPRING IS RAPIDLY COMPRESSED AND THE VALVE EXHAUSTS QUICKLY

8400 SCFM AT 50% OVERPRESSURE ON A 10 PSI PRD WAS TYPICAL. NOW THERE ARE DEVICES WHICH GO TO 12,600 SCFM.

Most frequent question: Will it protect? Most frequent question: Will it protect?

Most frequent answer is: Depends.Most frequent answer is: Depends.

•• location of faultlocation of fault•• magnitude of faultmagnitude of fault•• duration of faultduration of fault

The test tank was approximately 6 ft in diameter and 4 ft deep, The test tank was approximately 6 ft in diameter and 4 ft deep, with the with the PRD mounted in the center of the 6 ft. diameter cover. PRD mounted in the center of the 6 ft. diameter cover. The gas space was 10 inches below the cover which resulted in abThe gas space was 10 inches below the cover which resulted in about 700 out 700 gallons of oil and 23 cu. ft. of gas (air). gallons of oil and 23 cu. ft. of gas (air). Ball nosed copper electrodes (2) were threaded with a small coppBall nosed copper electrodes (2) were threaded with a small copper wire to er wire to trigger the arc, the highest of which was 25K amps and 20K voltstrigger the arc, the highest of which was 25K amps and 20K volts. Oil, . Oil, smoke, mist, spray blasted out of the relief device over a radiusmoke, mist, spray blasted out of the relief device over a radius of about 40 s of about 40 feet. feet.

TEST 1: 1958 AT GE SCHENECTADY

In tests performed by Jim Barr on a transformer with NO COIn tests performed by Jim Barr on a transformer with NO COVER , the fault VER , the fault was introduced near the bottom of the tank and the bottom of thewas introduced near the bottom of the tank and the bottom of the tank BLEW tank BLEW OUT, at 10K amps and 10K volts.OUT, at 10K amps and 10K volts.

TEST 2: 1958 AT GE SCHENECTADY

Transformer Tank Rupture and Mitigation - March 9, 2010 J.Herz,

Qualitrol

There are thousands of events where rupture There are thousands of events where rupture discs and rediscs and re--sealable PRDs have successfully sealable PRDs have successfully protected transformers: protected transformers:

““Internal arcing, breaker insulation break Internal arcing, breaker insulation break down, load tap changer problems, phase down, load tap changer problems, phase angle regulator problems, and internal angle regulator problems, and internal winding problemswinding problems””

are some of the more are some of the more

common.common.

CONCLUSIONS

TTR is a complex problem. The severity is a function of arc location, arc I and T as well as oil volume and tank expansion characteristics.

It’s possible to reduce the risk of TTR by performing modifications to the tank.

PRDs help to protect the tank against low energy internal arcing faults.

Fluids with high fire point will reduce the consequences of a tank rupture; however it is not yet proven if these fluids will prevent tank rupture.

GITs will eliminate the risk of tank rupture.

Improved electrical protection and electrical system design can also help prevent TTR.

The IEEE currently has no standards that provide guidance on TTR mitigation.

Power Transformer Tank Rupture and Mitigation- A Summary of Current State of Practice and Knowledge

by the Task Force of IEEE Power Transformer SubcommitteeNick Abi-Samra, Javier Arteaga, Bill Darovny, Marc Foata, Joshua Herz, Terence Lee, Van Nhi Nguyen,

Guillaume Perigaud, Craig Swinderman, Robert Thompson, Ge (Jim) Zhang, and Peter D. Zhao

IEEE TRANSACTIONS ON POWER DELIVERYVolume: 24 Issue: 4 Date: Oct. 2009 Page(s): 1959 - 1967

Action Next – Planning to Generate an IEEE Std

You are all welcome to join

s10 tr-tank rupturetutorial

Business

full scale model

pressure relief device

oil filled transformers

tank rupture due

transformer tank rupture

pressure rise

tank strength

tank rupture