PTFR-NHigh Current Bushings 36 kV up to 36 kA

BUSHINGS

1

Customer Benefits • Bushings with longer lifetime and higher reliability • No performance reduction with age • Partial discharge free

GRID

OIL-TO-AIR - Resin Impregnated PaperHigh Current - IEC and IEEE Standards

PTFR-N are capacitance graded bushings with resin impregnated paper insulation. They are designed for use on power transformers, installed in any position, in compliance with the latest edition of IEC 60137 and IEEE C57.19.01 - 2000. Design, components and manufacturing technology guarantee an average life time longer than 30 years under normal operating conditions.

Manufacturing of capacitance graded bushings

The main electrical component is the condenser body that is manufactured using resin-impregnated paper technology.

This technology utilizes a continuous sheet of pure crepe paper, wound around a support tube. During the winding process, the first step is to reduce its water content to a minimum by drying the paper with heated cylinders and infrared rays. During winding, a series of aluminum foils are coaxially inserted between the layers of the paper in order to grade the best possible distribution of radial and longitudinal electrical gradients between the central conductor and the grounded flanges.

The bushing is designited as follows:PTFR-N.36-200-10000

PTFR-N Condenser bushings for use on transformer, High Current, Resign impregnated Paper (RIP) technology

36 Rated voltage (kV)

200 BIL (Basic Insulation Level) in kV

10000 Rated Current (A)

AN ALSTOM COMPANY

The winding and foil placement is made by computer-controlled machines. After winding, each condenser core is placed into an autoclave for resin impregnation under vacuum. Each core is then machined to achieve the final shape.

CONDENSER BUSHINGS PTFR-N

2

1. Dry filling2. Condenser body 3. Porcelain insulator4. Flange

Air side

The air side envelope is made of brown colored porcelain. The creepage distance is for a very high polluted atmosphere (VHP) equivalent to 31 mm/kV. The shed configuration is alternate-type (small-large sheds). This is the most effective solution, proven by salt tests and the profile of sheds complies with the recommendations of IEC 60815.

The air extremity of the bushing inner conductor is provided by two or more palms for the connections of the bus bars, which are normally enclosed in a metal clad duct.

Oil side

The condenser body is immersed in the transformer oil and is hermeti-cally sealed to the flange. The springs, located on the oil side, are used for mechanical coupling of all bushings parts and to avoid shifting due to the thermal variations. The oil extremity of the inner conductor is provided with one or more palms for the connection to the transformer windings.

Current ratings

The acceptable operating currents versus oil temperatures and busduct air compared to conductor can be calculated using the following formula:

Ina = In x α x b

where: Ina continuous admissible current [A]In nominal bushing current [A] α temperature coefficientb CT space coefficient

α and ß can be determined using the tables here below, where:Tc admissible conductor temperature (120°C) E classTa ambient (bus duct) air temperature (°C)To transformer oil temperature (°C)K CT space (mm)

Conductor and terminals

Both sides of the conductor and terminals are made from a unique cast aluminum alloy, which has an IACS 55% conductivity.

Terminal surfaces are not treated. Upon request it is possible to provide them with 10 micron silver plating.

Fig. 1: Section

Main featuresPTFR: Resin Impregnated Paper High current IEC Standards

Rated voltages: 36 kV

Air side: porcelain insulator

Oil side: Resin Impregnated Paper winding

Inner conductor made of cast aluminum

Dry filling of the interspace between porcelain and condenser body

Installation in any position

Flange of aluminum alloy casting

Maximum current rating up to 36.000 A

Flange provided with power factor tap and Buchholz relay connection

1

2

3

4

CONDENSER BUSHINGS PTFR-N

3

Fig. 2: Power factor tap

1. Measurement electrode2. Insulating bushing3. Tap body4. Gasket5. Closing and grounding cap

2 53 4

1

ø 8 mm

Flange

The flange is made from cast aluminum, and is equipped with lifting holes, a power factor tap (can withstand 3 kV for 60 s) (fig. 2) and Buchholz relay connection (1/2” gas outlet plug) (fig. 6).

Flange surface treatment

Power factor tap surface finish avoids any corrosion throughout lifetime and allows for easy screwing and unscrewing in service. Further finishing or final painting are the customer’s option.

Assembling

The coupling between porcelains and metal parts (flange and inner conductor) is achieved with belleville washer-type springs, placed in the oil side of the bushings.

Gaskets

Made of Viton® a fluorocarbon rubber elastomer (FPM), o-ring type. They are compatible with all the fluids they are in contact with (transformer mineral oil). Air side gaskets are carefully protected, by means of a sealing, against influence of polluting weather elements. For special requirements, such as low ambient temperatures (down to -55°C), special o-rings are used.

Dry filling

PTFE bushings can be installed in any position because the interspace between porcelain and condenser body is filled with a dry mass (polyurethane).

This material offers:

Low dielectric losses Good level of partial discharges Good thermal resistance Constant characteristics versus time

Dry filling improves reliability in comparison with oil filled type and makes installation simpler: no oil leakage and, if horizontal instal-lation, no oil reservoir.

Tests

All bushings have electrical characteristics that are tested in compliance with the last edition of CEI IEC 60137-Publication INSULATED BUSH-INGS FOR ALTERNATING VOLTAGES ABOVE 1000 V, and Main National Standards.

Name plate

Each bushing is provided with a name plate, (fig. 4) with all the electrical data and serial number, in accordance with the prescription of IEC Stand-ards. The stainless steel plate is placed on the flange by rivets.

Tc - Ta (°C) Coefficient α (36 kV TYPE)90 0.76 0.83 0.92 0.99 1.0680 0.72 0.79 0.88 0.96 1.0370 0.67 0.76 0.85 0.93 1.0160 0.63 0.73 0.82 0.91 1.0050 0.59 0.70 0.79 0.89 0.9940 0.55 0.66 0.76 0.86 0.9630 0.50 0.63 0.73 0.84 0.9520 0.46 0.59 0.70 0.81 0.9310 0.43 0.56 0.67 0.79 0.91

Tc - T0 (°C) 10 20 30 40 50

CT space Coefficient bK (mm) 24 kV TYPE 36 kV TYPE

Ta = 40°C Ta = 80°C Ta = 40°C Ta = 80°C0 1.00 1.00 1.00 1.00

100 0.94 0.99 0.97 0.99200 0.87 0.97 0.90 0.95300 0.81 0.95 0.84 0.91400 0.75 0.91 0.79 0.87500 0.68 0.87 0.75 0.83600 0.61 0.81 - -700 0.55 0.75 - -

PASSANTE-BUSHING-TRAVERSEE-DURCHFUHRUNG

50-60Hz

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Fig. 4: Nameplate

Fig. 3: PTFR-N dimensions

1. Bushing type2. Insulating voltage3. Rated current 4. Max. mounting angle

off of the vertical5. Weight6. Blank (available) 7. Serial number8. Month - year of final tests

CONDENSER BUSHINGS PTFR-N

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Alstom Grid Worldwide Contact Centre www.grid.alstom.com/contactcentre Tel.: +44 (0) 1785 250 070 www.grid.alstom.com

GRID

To contact the manufacturerViale Suzzani, 229 20162 MILANO (Italy)Tel: +39 02 661 221Fax: +39 02 647 09 06Email: rpv@alstom.com

Following the acquisition of PASSONI & VILLA, Alstom Grid now offers a large portfolio of condenser bushings for AC or DC operation. If you require any further information, please address your queries to

rpv@alstom.comAN ALSTOM COMPANY

Type high current bushing 36 kV All applications

36-2

00-1

0000

36-2

00-1

6000

36-2

00-2

5000

36-2

00-3

6000

Type & current

Rated current [ka] 10 16 25 36

Rated thermal short time current, 2s [ka] 100 100 100 100

Rating acc.IEC 60137

Rated voltage [kv] 36 36 36 36

Ur/√3 [kv] 21 21 21 21

AC voltage test dry & wet [kv] 70 70 70 70

BIL 1.2 / 50 μs [kv] 170 170 170 170

Rating acc.IEEE c57.19.01

System voltage [kv] 34.5 34.5 34.5 34.5

Max. rated line to groung [kv] 22 22 22 22

AC voltage test dry & wet [kv] 80/75 80/75 80/75 80/75

BIL 1,2 / 50μs [kv] 200 200 200 200

Performance & mechanics

Min. nominal creepage distance [mm] 1120 1120 1120 1120

Min. nominal arcing distance [mm] 320 320 320 320

Cantilever withstand load [kN] 5 5 5 5

Pollution class heavy heavy heavy heavy

Operating attitude [m] 1000 1000 1000 1000

CT [mm] 0-100-300

0-100-300

0-100-300

0-100-300

Dimensions bushing

D1 dielectrical insulation support [mm] 300 400 630 840

D2 diameter of inner sealing area [mm] 300 400 630 840

D3 diameter of flange bolt circle [mm] 400 535 720 930

D4 max. diameter of flange [mm] 450 590 780 990

D5 max. diameter of top al-flange [mm] 380 480 710 920

D6 max. diameter of porcelain outer diameter [mm] 540 640 870 1080

Dimensions conductor (without fittings)

ø [mm] 240 340 570 780

L=0 [mm] 625 625 625 625

L=100 [mm] 725 725 725 725

L=300 [mm] 925 925 925 925

Mainflange

øi [mm] 290 390 620 830

Length [mm] 85 85 85 85

z [mm] 20 22 22 22

n [number] 12 16 16 16

Condenser core

øi tube [mm] 240 340 570 780

øa tube [mm] 250 350 580 790

øa RIP [mm] 300 400 630 840

Lcore/0/100/300 [mm] 535/635/ 835

535/635/ 835

535/635/ 835

535/635/ 835

k [mm] 140/240/ 440

140/240/ 440

140/240/ 440

140/240/ 440

Fig. 5: Flange fixing holes Fig. 6: Buchholz relay connection

Ø 20 45°

M12

1021

1055

840

125

808

140

8532

014

0

L.TO

T.

20 460 20

500

36°

290

25

710

R260

240

R127.5

170

125

80

K14

085

320

140

481

515

300

L. T

OT.

120

25

20020 20

380

240

45°

515

811

845

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5

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500

36°

290

25

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R260

240

L.TO

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140

85K

581

400

80

615

125

320

140

25

20 200 20

240

R127.5480

170

45°

120