toshiba git

7/29/2019 Toshiba Git

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50kV-4kVA TR

Start manufacturing in 1894

Worlds first by Ganz 1050kV-3000/3MVAUHV TR

330kV-400MVA GIT(Worlds largest)

66kV-3000kVA GIT

(Japans first)

275kV-99MVA TR(Japans first)

220kV-80MVA TR(Asias first)Almost sameyear as Europes

first operation

525kV-1450MVA TR(Worlds largest) Fig.1

Toshiba TransformersHistory & Background

Only 9 years after the worlds first transformer was manufactured, Toshiba started supplying transformers

to the market in 1894. Since then, Toshiba has been one of the most innovative transformer manufacturersin the world. In 1967, Toshiba delivered the first GIT, 66kV, 3MVA transformer to the market, which features

excellent characteristics for safety and environmental friendliness.

As power consumption in urban areas increases, a large number of substations have been constructed

underground, beneath commercial buildings, parks and public spaces. Safety and the avoidance of fireincidents is the most important consideration for substations in urban areas. Compact and cost effective

solutions are required for substations installed in areas where space is limited. Gas insulated transformers(GITs) instead of Oil immersed transformers (OITs) offer the best solution for overcoming the sharp increase

in electric power demand in large cities.

History of Toshiba Power Transformers

GIT World wide application Underground Substation within a business complex

1

Application: GITs excel in explosion-proof safety and are

widely used in underground and indoor substations in urban

areas. GITs are also installed in environmentally critical

areas where oil leakage is prohibited.

Toshiba has supplied a large number of GITs all over

the world and there are many GIT projects planned for

the future.

As of 2008

Supplied

Under discussionFig.2 Fig.3


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Pressure rise during fault is small

SF6 Insulation Non-flammable

Non-explosive

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1 1.2

OIT

GIT

Fault Time(sec)

PressureRise(%) Tank Strength

Pressure rise of GIT is very small

TRANSFORMER ROOM

GIT

GIB

GISROOM

CONSERVATOR

OIL TRANSFORMEROILCABLEBOX

PRESSURERELIEFDEVICE

> Close Arrangement of

Transformers and GISWithout Partitions> Low Ceiling Substation Room

* No Conservator andPressure Relief Device

150MVA-275kV Shunt Reactor

300MVA-275kV GIT GIS

Advantages of GIT Technology

Excellent features of GIT

GITs employ SF6 gas as the insulation & cooling medium, which avoids the need for fire

fighting equipment, oil collection tanks and pits outside the transformer room.

Since the rise in tank pressure for an internal fault is very small compared with the GIT

tank withstand strength, the GIT tank will not explode on internal fault ensuring the safety

of equipment within the substation.

Since neither a conservator nor pressure relief arrangement is required, the height of the

transformer room can be reduced. For the case of a 275kV 300MVA class application,

approximately 2 to 2.5 meter reduction in height can be achieved.

The application of GIT together with GIS offers a very compact substation design as the

equipment is installed in the same room. A significant cost reduction for civil construction

can thus be achieved.

Features Advantages with GIT

Non-flammability

Non-explosive feature

Compactness

Excellent interface withGas Insulated Switchgear(GIS)

Pressure rise on internal fault

Compact substation design throughapplication of GIT

2

As oil is not used in a GIT, a fire wall between the GIT and

GIS or separate rooms are not required. Therefore GITand GIS can be instal led in the same room. This

arrangement enables a compact substation to beachieved.

Significant tank pressure increases do not occur during

internal failures due to the Gas characteristics. The risk of

a tank explosion or fire incident can be completelyeliminated.

Fig.4

Fig.5


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Insulation / Cooling

Insulating Oil SF6Pressure 0.14 or 0.43MPa-g(20)

Solid Insulation Material

Oil Impregnated Paper, Pressboard PET Film,PPS Film, Aramide Paper,Pressboard

Conservator

Necessary Unnecessary

On-Load Tap Changer

Diverter Switch

Arcing Switching in Oil Vacuum Interrupter

Tap Selector

Slide Contact Roller Contact

Construction

The construction of a GIT is basically the same

as an OIT, with the exception of insulatingmaterial and cooling medium. Therefore, broad

experience of OIT technology can be applied toGIT design, manufacturing and maintenance.

Features of GIT

3

Oil Immersed Transformer(OIT)

Gas Insulated Transformer(GIT)

Fig.6


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Air Outlet

Air Inlet

Cooling Fan

Air Cooler

Commercial building

Cooling system

The concept of the external cooling design for a GIT is nearly the same as that for an OIT; for this reason

various types of cooling method can be applied.

4

Cooling design for GIT

Since the head pressure of SF6 gas is negligiblylow, cooling equipment can be located above the

GIT level as indicated in the figure. The GIT offersexcellent flexibility when locating components

such as radiators or coolers.

A water cooling system is widely used in large-capacity

underground and/or indoor substations. The heat

generated from a GIT is efficiently transferred towater-air heat exchangers by water flow. The coolingsystem is usually located on the top floor of the

substation building.

Flexibility in substation design Water cooling system forurban substations

GDAN/GDAF-20/63MVA - 110kV GIT

1. GNAN Type 2. GDAN Type 3. GDAF Type 4. GDWF Type

RadiatorGas Blower

Radiator

Gas Blower Gas - WaterHeat-Exchanger

Cooler

Water

Gas to Water

Circulating water pumpUnderground

Gas Watercooler

Gas Blower

Silencer

Water to Air

Gas to Water

P

Fig.7

Fig.8 Fig.9


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Fig.10

Fig.11

Computer AidedEngineering (CAE)

Radiator coolingWinding cooling

Transformer room cooling

5

Temperature analysis for GIT design and GIT room considerations

In the cooling design for the GIT winding or substation buildings, Computer Aided Engineering (CAE)

methods can be applied. The calculation using CAE for the airflow inside the building and/or outside isvery useful during the planning stage of the substation building.

The calculation result used in the figure shows that the top cooler arrangement is suitable in terms of

efficient substation cooling for this case. Positions of coolers can be decided by carrying out the CAE

analysis taking into consideration the arrangement of the substation.

Air Temperature distribution Air velocity vector and distribution

Exhaust Flow Late = 760m3/min, No-Duct

Coil

HorizontalCooling Duct

Gas Stopper

Gas Stopper


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Fig.12

Interface with other substationequipment

Cable connection

6

There are various types of terminal construction for GIT applications. In order to reduce the space required

for the terminal construction, cable connection or GIB direct connection is widely applied instead of airbushing connection especially for underground or indoor substations.

The cable interface construction is well defined and termination

work can be done in a secure manner in accordance with theinternational standard (IEC or others).

Plug-in connector interface

Gas treatment work at the cable compartment is not required

during installation work in the case of the plug-in connector. Aplug-in connector is usually only applied for small capacity, low

voltage GITs due to availability of the connector.

Gas Insulated Busbar (GIB) direct connection

GITs can be installed together with GIB or GIS in the same

room by applying either GIB or GIS direct connection as shownin Fig. 5 on Page 2.


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Type GVT-D100AL GVT-M100CL GVT-100DH

Photo

Step Voltage

Rated Current

1200V 1500V 2500V

380A 600A 870A

On-Load Tap Changers (OLTC)& Accessories

Temperature indicationSudden gas pressure relay

Line-up of OLTC for GIT

7

Comparison between accessories for GIT and OIT

Item GIT OIT

ProtectiveDevice &

Accessory

Air ventilation

Temperature

Leak

Protection

Others

Gas Temperature IndicatorWinding Temperature Indicator

Oil Temperature IndicatorWinding Temperature Indicator

Oil Preservation SystemDehydrating Breather

Ventilation with fireproof dampers tooutdoors

Buchholtz relay, Gas detection relay,Pressure relief device,

Gas density relayCompound gauge

Sudden gas pressure relay (OLTC)

Oil Level gauge

Ventilation to outdoors

SENSING UNIT

DIAL TYPE THERMOMETER

RESISTANCEBULB

GAS WTI

Fig.14 Fig.15

Fig.13

Table.1


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Diagnostics & Maintenance

GIT Diagnostics

GIT Maintenance Program (Example)

8

NO. Maintenance Item

1

2

3

4

5

6

7

8

9

10

11

12

Gas analysis

Replenish the bearing grease of gas blower

Gas blower bearings

Exchange Gas blower

Indication and protection devices

Exchange Gas pressure sensor

Exchange Bushing

Exchange control cable Wiring

Inspection of OLTC

Exchange a Cooler

Exchange O-ring, Gasket

Running repairs of small gas leakage

when failureoccur

30 yearsEvery

15 years

Every

10 years

Every

5 years

Every

3 years

Every

2 years

Required maintenance period

Maintenance cycle & items for GITs

Fig.16

Table.2

The integrity of GITs can be checked and a failure cause analysis can be made using gas chromatography.Using a simple gas detective tube device, GIT integrity can be confirmed at site.

Gas sampling bag

Gas detective tube


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Typical application

400MVA GIT in underground substation15/50MVA - 110kV GIT in underground substation

OIT and GIS application GIT and GIS application

9

As oil is not used in both GIT and GIS equipment,neither a fire wall nor separate rooms are required. Byinstalling both GIT and GIS in the same room, acompact substation can be realized.

Toshiba supplies a wide range of GITswith low pressure gas and high pressuregas technology.

OIT and GIS must be separated by a fire wall orinstalled in separate rooms dependent upon the firerisk.

Low pressure design:

0.14MPa-g

High pressure design:0.43MPa-g

Applied Voltage, Capacity & Gas pressure

Voltage

(kV)

Capacity (MVA)

275

154

500

66

22

10 200 30010068

Low PressureSmall Capacity

High PressureLarge Capacity

Water cooling system is applied

Fire extinguisher

Gravel fillingoil catch pit

Long GISinterface

High ceiling

Fire wall

GIT substation is simple & small

Lower ceiling

Substation size is half

Fig.17 Fig.18

Fig.19

Fig.20

Fig.21

0.43Mpa-g

0.14Mpa-g


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Environmentally friendly feature

39MVA-132kV GIT near Australian national park

SF6 gas emission from gas-insulated equipment in Japan Gas leak test at the factory

10

In order to confirm no gas leakagefrom the GIT tank, gas leak testsare performed at the factory for allGIT tanks. At site the gas leaktest is performed on re-assembledparts to ensure no leakage.

Electric power companies and Electric equipment manufacturers in Japan have made tremendous efforts to reduce

SF6 gas emissions based on an agreed voluntary target. With careful gas treatment and complete SF6 gas recoverysystems, the amount of SF6 gas emission from gas insulated equipment has been dramatically reduced as indicatedby the green bars.If no action had been taken, the amount of SF6 gas emissions would still be increasing as indicated by the orangebars.

The Hydro Power station shown in this photograph is located in the wet tropical area within a worldheritage site. A GIT was provided at the power station to remove the risk of oil leakage.

With Action Without Action700

600

500

400

300

200

100

0

1990

1992

1994

1996

1998

2000

2002

2004

2006

2010

SF6Emissions(t)

Control for SF6 gas emission

28.729405065

86117

209

378449

491

Fig.22

Fig.23

Fig.24


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toshiba git

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