sttpgaaa31e - tp presentation for bdam - copy

During a transformer short circuit, the TRANSFORMER PROTECTOR is activated within milliseconds by the firstdynamic pressure of the shock wave, avoiding transformer explosions before static pressure increase

TRANSFORMER PROTECTOR

The Only Solution Against Transformer Explosion

www.transproco.com

TRANSFORMER PROTECTOR Presentation

TRANSFORMER PROTECTORThe Only Solution Against Transformer Explosion

1/ Transformers explosions2/ TP principle3/ Physical explanations4/ Technical description5/ TP References

Ref: StTPgaaa31e 2

NFPAThe TRANSFORMER PROTECTOR is now recommended for all Power Plants and Substations in the National Fire Protection Association 2010 edition of:• NFPA 850 (Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations),• NFPA 851 (Recommended Practice for Fire Protection for Hydroelectric Generating Plants).

The introduction of the 2010 edition of NFPA 850 & NFPA 851 stands : “Fast depressurization systems have been recognized, and recommendations for the use of these systems are now included”

“Fast depressurization system: a passive mechanical system designed to depressurize the transformer a few milliseconds after the occurrence of an electrical fault”

More details later in the presentation or

Just click here

2



Ref: StTPgaaa31e 3

1. Transformers are very dangerous

• Examples of explosions

• Conventional protections

• The answer

1. Transformers are very dangerous



Ref: StTPgaaa31e 4

Danger :

• The whole power plant (1,350MW) was out of service for 4 months.

• The damaged section (450 MW) was out of service for 13 months.

• 2 people were badly burned.• Fire extinguishing systems did not

work.• Security fire doors were too slow.

Transformer explosion in substation :

Power transformers are very dangerous

Transformer explosion in substation

•Large quantity of oil in contact with high voltage elements•No international security norm for transformers

1. Transformers are very dangerous Examples of explosions

Click on picture to watch video



Ref: StTPgaaa31e 5

Other explosion examples

Krümmel Nuclear Power Plant, GermanyJune 2007, still not restarted !

Cost: 1 Million USD / day !

3Transformer explosions lead to:

• Huge fire

• Plant outage

• Huge costs : hundreds millions USD

• Ruin company reputation

• Environmental pollution

• Human life risks

1. Transformers are very dangerous Examples of explosions

5



Ref: StTPgaaa31e 6

1. Transformers are very dangerous Conventional protections

a) South Bend, Indiana , USA, 1999

Efficiency ?Corrective Means

• Firewalls • Fire extinguishing systems

Limit fire propagation induced by the explosion Fire propagated from one transformer

to the other

1

6



Ref: StTPgaaa31e 7


b) Venice Plant, Illinois , USA, 2000

Efficiency ?Corrective Means

Solution : Preventing transformer explosion to avoid fire

• Firewalls • Fire extinguishing systems

Limit fire propagation induced by the explosion

Fire propagated to the whole plant: All 9 transformers caught fire despite fire

walls and fire extinguishing systems (cost: USD 230 millions)

1

7



Ref: StTPgaaa31e 8


All exploded transformers

were equipped with these

devices

Efficiency ?Preventive Means

• Circuit breakers

• Buchholz Relay

• Sudden Pressure Relay

• Gas Monitoring

• Pressure Relieve Valve

Solution : The protection must act faster !

2

8



Ref: StTPgaaa31e 9

1. Transformers are very dangerous The answer

During a short circuit, the TP is activated within milliseconds by the first dynamic pressure peak of the shock wave, avoiding explosions by preventing static pressure increase.

The TP key of success

The TRANSFORMER PROTECTOR (TP)The TP depressurizes transformers within milliseconds

avoiding explosion and subsequent fire.

9



Ref: StTPgaaa31e 10

2. Preventing transformer explosion: the TP principle

• Transformer explosion process

• TP strategy to prevent explosion

• TP operation

• TP standard configuration

• TP operation movie

2. Preventing Transformer Explosion: The TP Principle

10



Ref: StTPgaaa31e 11

Why do transformers explode ?

Dielectric oil insulation rupture

Electrical arc

Oil vaporization

Local dynamic pressure increase

First dynamic pressure peak propagates

Dynamic pressure peak reflects off walls

Static pressure increases

Tank rupture & Fire

2. Preventing transformer explosion: the TP principle Transformer explosion process



Ref: StTPgaaa31e 12

How to break that sequence?


Electrical arc

Oil vaporisation




Static pressure increases

Tank rupture & Fire

2. Preventing transformer explosion: the TP principle Prevention strategy

12



Ref: StTPgaaa31e 13

Activation within milliseconds by the first dynamic pressure peak

Quick Oil Evacuation

Tank depressurization

Prevents the explosion

How to break that sequence?


Electrical arc

Oil vaporisation




2. Preventing transformer explosion: the TP principle Prevention strategy



Ref: StTPgaaa31e 14

2. Preventing transformer explosion: the TP principle TP operation

14



Ref: StTPgaaa31e 15


• Electrical arc• Pressurized gas bubble• Dynamic pressure peak propagation

15



Ref: StTPgaaa31e 16


Quick oil evacuation generating fast depressurization of the tank (within milliseconds)

TP Activation1


16



Ref: StTPgaaa31e 17


• Explosive gases remain• Melting parts of the windings are still emitting gases


TP Activation1


17



Ref: StTPgaaa31e 18


Evacuation of the explosive gases until the melted parts are cooled down (~ 45 mn)

Injection of Inert Gas2


TP Activation1



18



Ref: StTPgaaa31e 19


Transformer safe and ready for repair


TP Activation1

Evacuation of the explosive gases until the melted parts are cooled down (~ 45 mn)

Injection of Inert Gas2



19



Ref: StTPgaaa31e 20

2. Preventing transformer explosion: the TP principle TP standard configuration

Standard TRANSFORMER PROTECTOR (TP)

6

2

1 4

1. Vertical Depressurization Set (VDS)

2. OLTC Depressurization Set (OLTC DS)

3. Slice Oil-Gas Separation Tank (SOGST)

4. Explosive Gases Evacuation Pipe (EGEP)

5. Air Isolation Shutter

6. TP Cabinet

7. Inert Gas Injection Pipe (IGIP)

The ComponentsTP Components

7

3

5

20



Ref: StTPgaaa31e 21

2. Preventing transformer explosion: the TP principle TP operation movie

TP Operation Movie

Click on picture to watch video

21

Ref: StTPgaaa31eTRANSFORMER PROTECTOR



22

3. Physical Explanations and Testing of the TP Experimental tests: general overview

Two main test campaigns

ConclusionDuring the 62 tests, the TP always saved transformers from explosion without permanent tank deformation

• 2002: 28 tests by EDF (Electricité de France) on small transformers

• 2004: 34 tests by CEPEL (HV independent lab.) on large transformers (8.4m – 26ft long)

• Principle: electrical arcs were ignited inside transformers tanks equipped with a TP

Click on pictures to watch videos

22




23

3. Physical Explanations and Testing of the TP Vaporization saturation process

SKIP

1st key phenomena: oil vaporization & arc creation – video1

Arc movie during the EDF testsHigh speed camera 3000 fps

Chronology

0 ms : Start of applied current

3.66 ms : Bubble generation

4 ms : Bubble volume = 9 cm3, 0.5 in.3

4.33 ms : Bubble volume = 60 cm3, 3.7 in.3






6.33 ms : Electrical arc fully developed - plasma

23




24

3. Physical Explanations and Testing of the TP Dynamic / static pressure

• Spatially uniform all over the tank• Progressive, slow increase • Oil behaves as an incompressible

media• Max withstand ~1 bar – 15 psi (gauge)

• Very localized and moving in the tank• Propagates quickly within the tank• Oil behaves as a compressible media• Tank can resist 13 bar – 190 psi

(gauge)

The tank does not explode The tank explodes

Dynamic PressurePressure gradients over 25 bar/s – 360 psi/s

Static PressurePressure gradients under 25 bar/s – 360 psi/s

How does the PRV react to dynamic

pressure ?

Click here

Pressure gradients up to 5000 bar/s – 72000 psi/s

Propagation speed: 1200 m/s – 4000 ft/s

24




25

3. Physical Explanations and Testing of the TP Influence of the TP

a) No static pressure The quick oil evacuation generates rarefaction waves that depressurizes the tank before static pressure builds up.

0 ~10 ms

Arc occurrence

TP is activated

Tank is depressurized

~80 ms

Dyn. pressure travelling

Oil evacuation

Click on picture to watch videoThe DS is activated within milliseconds by the first dynamic pressure peak and evacuates pressure while tank structure inertia to rupture is much higher.

The breaking section to open the precut Rupture Disk at the dome is more than 50 times less than the section of tank bolts.

Very small section to break to activate TP

6th key phenomena: the TP depressurizes tanks preventing explosion6

25




50 ms

30 ms

10 ms

4 ms

1 ms

100 ms

26

50 ms60 ms70 ms80 mst =

Static pressure builds up

Dynamic pressure reach more than 9 bar – 130 psi (gauge) in a bushing

Reflects off the walls and creates complex pressure waves

Gas bubble under pressure

The first dynamic pressure peak propagates

Static pressure stabilizes at 5.5 bar – 80 psi (gauge)

100 ms

Transformer explodes

3. Physical Explanations and Testing of the TP Simulation tool – 200 MVA transformer – no protection

11 MJ electrical arc

Max. static withstand limit pressure of transformer tanks :

1.2 bar – 17 psi (gauge)

Pressure (gauge) (psi) (bar)

without TP




1 ms

27

70 ms80 ms100 mst =

After 60 ms

11 MJ electrical arc

Gas bubble under pressure

150 ms

3. Physical Explanations and Testing of the TP Simulation tool – 200 MVA transformer – with TP

4 ms

10 ms The dynamic pressure peak activates the TP

The first dynamic pressure peak propagates

15 ms

30 ms

60 ms

The tank depressurizes

Rarefaction waves are spread in the tank

The tank is fully depressurized

without TP

with TP

• without TP, static press. = 5.5 bar – 80 psi


• with TP, static pressure = atm. pressure

without TP

with TP




after 120 ms

28

3. Physical Explanations and Testing of the TP Simulation tool – Real case study – 400 MVA transformer

• Without TP, the max. pressure is 14 bar – 200 psi and the static pressure builds up at around 7 bar – 100 psi.

the tank explodes

• With TP, the first dynamic pressure peak activated the TP within milliseconds before static pressure is built up.

the tank is safe

with TPwithout TP


after 120 ms after 120 ms

28



Ref: StTPgaaa31e 29

4. TP Technical Description Retrofitting on existing transformers

The TRANSFORMER PROTECTOR is easily retrofitted without tank machining by using the existing interfaces

1. Depressurization Set: Cover and Side Manholes, Pressure Relief Valves and Existing Valves can be used for the adaptation

SKIP

Retrofitting on existing transformers

29



Ref: StTPgaaa31e

Retrofitting on existing transformers

30

4. TP Technical Description Retrofitting on existing transformers

The TRANSFORMER PROTECTOR is easily retrofitted without tank machining by using the existing interfaces

1. Depressurization Set: Cover and Side Manholes, Pressure Relief Valves and Existing Valves can be used for the adaptation

2. Inert Gas Injection: Existing Valves for oil sampling and draining can be used to retrofit the inert gas injection

30



Ref: StTPgaaa31e 31

5. References Financial benefit

The TP Financial Benefit is very high

The Protection Financial Benefit (PFB) is calculated as :PFB = CTC / (MLEB – LEA)

For corporate risk managers and insurance, if:• PFB < 1 %, the protective technology is highly recommended• 1% < PFB < 4%, insurance companies adjust their rates and premiums

Analyses showed that the TP Financial Benefit varies from 0.015 % to 0.06 % !

When an incident occurs, the TP compensates several thousand times the investment

• CTC (Cost To Complete) : complete price of the protection (including erection and tests)• MLEB (Maximum Loss Expectancy Before): cost of the worst recorded incident before

installing a protection• LEA (Loss Expectancy After): evaluation of the damage cost of the worst recorded incident

with the chose protection after installation

Extract from “Transformer Explosion and Fire Incidents, Guideline for

Damage Cost Evaluation, Transformer Protector Financial Benefit”

Available on request

31



Ref: StTPgaaa31e

Generation Transmission Distribution

32

5. References Sold TP

More than 1.400 TP sold since 2000

Every kind of oil-filled transformers (above 1 MVA)

32



Ref: StTPgaaa31e 33

5. References End users

More than 106 companies in 53 countries:

• Australia: Delta Electricity• Brazil: Abengoa, Tractabel,• France: EDF• Germany: Vattenfall

•Jordan: JEPCO, NEPCO•Mexico: CFE•Namibia: NamPower•Russia: Rusgidro, FNK

•Qatar: Kahramaa, Qatar Petroleum•South Africa: Eskom, City Power•Spain: Metro de Madrid•USA: PG&E, Sunflower Electric

33



Ref: StTPgaaa31e 34

5. References NFPA

• Standard NFPA 850 (Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations)

• Standard NFPA 851 (Recommended Practice for Fire Protection for Hydroelectric Generating Plants)

The NFPA recommends the TP

In the introduction of NFPA 850 and 851:

34



Ref: StTPgaaa31e 35

5. References NFPA

Definition of “fast depressurization system” by the NFPA:




35



Ref: StTPgaaa31e 36

5. References NFPA

Explanation of the operation by the NFPA:




Documents available on

request

36



Ref: StTPgaaa31e 37

FM Global : Certification under progress

NFPA : TP is recommended in the standards 850 & 851 and in the NFPA Fire Handbook 2002 & 2008

EDF (Electricité de France) and CEPEL (Brazil) laboratories TP tests validation

Active participation in the Power Transformer Subcommittee (tank rupture mitigation taskforce)

Various IEEE Conferences

Active participation in the A2 Study Committee – Transformers (transformer fire safety practices WG)

Various Cigré Conferences

5. References Valorization or certification organisms

37



Ref: StTPgaaa31e 38

5. References Successful activations

• Romania (TransElectrica), • Philippines (Transco), • Botswana (Botswana Power Corporation),• Activation in Pakistan, Mexico (3) and Romania under

process

The TP saved transformers, successful activation certificates from:

38



Ref: StTPgaaa31e

with TP without TP

after 100 ms


39

Conclusion

Brazil Germany France

• The NFPA Fire Handbook emphasizes the TP technology• Several successful activations• More than thousand TP sold all over the world (USA, Europe, Middle East…)

3. The TP is a recommended solution

• Principle: No Actuator !The TP is activated by the first dynamic pressure peak generated by the arc, avoiding the explosion by preventing static pressure increase

• Efficiency demonstrated by experimental tests & numerical simulations

2. The TRANSFORMER PROTECTOR prevents the explosion

• Explosions are more and more frequent• Dangerous, expensive, polluting, hurt reputation…• Conventional corrective means do not prevent explosion (fire extinguishing systems,

firewalls)• Conventional preventive means are not efficient (circuit breakers, buchholtz, PRV...)

1. Power transformers are very dangerous

39

During a transformer short circuit, the TRANSFORMER PROTECTOR is activated within milliseconds by the firstdynamic pressure of the shock wave, avoiding transformer explosions before static pressure increase

TRANSFORMER PROTECTOR


www.transproco.com



Ref: StTPgaaa31e 41

5. References CEPEL (Brazilian independent laboratory)

Back to the presentation

Click here

41



Ref: StTPgaaa31e 42

3. Physical Explanations and Testing of the TP TP – PRV reaction to dynamic pressure

TRANSFORMER PROTECTOR Pressure Relieve Valve (PRV)

How does the PRV react to dynamic pressure ?

42



Ref: StTPgaaa31e 43

• Spring inertia to open: 5 ms• PRV reacts to dynamic pressure for

0.1ms PRV diameter: 15 cm - 6 in. Dyn. press. speed: 1200 m/s – 4000 ft/s

• activated by dynamic pressure peak • depressurizes the tank within

milliseconds• prevents static pressure increase

The tank does not explode Dynamic pressure peak too

fast to activate the PRV

TRANSFORMER PROTECTOR Pressure Relieve Valve (PRV)

0.1 ms

3. Physical Explanations and Testing of the TP TP – PRV reaction to dynamic pressure

43



Ref: StTPgaaa31e

3. Physical Explanations and Testing of the TP PRV reaction for lower pressure gradient

Even for lower pressure gradients, the PRV is not adapted• 1st step : spring inertia is 5 ms• 2nd step: when the PRV is 50% open, only 15% of the section is used to

evacuate the oil

Evacuation Section only 15% when half open

0%

50% Spring inertia 5 ms

44



Ref: StTPgaaa31e


Even for lower pressure gradients, the PRV is not adapted• 1st step : spring inertia is 5 ms• 2nd step: when the PRV is 50% open, only 15% of the section is used to

evacuate the oil• 3rd step: oil has to make a “U turn” to escape, the evacuation is slowed

down• 4th step: even when the PRV is fully opened, only 80% of the section is used

Evacuation SectionOnly 80% of 6’’ when

fully open

0%

50%

100%

U turn for the oil evacuation

45



Ref: StTPgaaa31e


What is the use of the PRV ?

• PRV is not adapted for low impedance fault (arcing)• PRV is designed for slow pressure increase to relieve low static

overpressure High impedance fault Low temperature increase Very slow gas creation …

Back to the presentation

Click here

4646