— 1ZSC0 0 0563 - A AW EN, RE V. 2

Transformer bushings type GSCTechnical guide

— Original instructionThe information provided in this document is intended to be general and does not cover all possible applications. Any specific application not covered should be referred directly to ABB, or its authorized representative.

We reserve the right to make technical changes or modify the contents of this document without prior notice. With regard to purchase orders, the agreed particulars shall prevail. ABB does not accept any responsibility whatsoever for potential errors or possible lack of information in this document.

We reserve all rights in this document and in the subject matter and illustrations contained therein. Any reproduction, disclosure to third parties or utilization of its contents – in whole or in parts – is forbidden without prior written consent of ABB.

— Table of contents

Design 5Standards 5Features and benefits 6Transportation and long term storage 6

Testing 7Test tap 7Test tap adapter 7

Electrical data 8

Dimensions 9

Connection details 10Outer terminal 10End shielding of the outer terminal area 10Draw rod system 11

End shielding of the bottom contact area 12

Conductor loading and mechanical loading 13Conductor loading 13Mechanical loading 13

Recommendations for positioning 14

Ordering particulars 15

TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E 5

GSC is a Resin Impregnated Paper (RIP) bushing intended for immersed oil to air DC application. The bushing is manufactured by winding the condenser core onto the conductor tube, which is either aluminum or copper. The core consists of crepe paper with conductive inserts of aluminum foil to provide for electrical stress control, and is impregnated with epoxy resin and cured in a vacuum. The manufacturing method provides a partial discharge free bushing with low dielectric dissipation factor (tan δ).

After curing, the core is machined and a flange and an insulator are fitted. The insulator is made of composite with silicone rubber sheds provided with flanges at both ends.

The space between the RIP core and the inner surface of the hollow core insulator is filled with insulating gel.

The current path through the bushing is from the bottom contact through the conductor tube to the top outer terminal. The oil-side connection is made with a draw-rod system, which is a steel rod installed inside the conductor tube to provide the mechanical contact force of the bottom contact to the bushing conductor.

For the air side connection there are studs available in a number of standard configurations, but it can also be modified to suit any connection need.

The GSC bushing is intended for operation on the valve side of an HVDC converter transformer, where a common installation procedure involves near horizontal mounting. The dry design of the RIP core is particularly suitable for the application and allows most angles commonly used for the application.

The standard color of the composite insulator is ANSI 70 light gray.

For a converter transformer designed with its turret external to the valve hall wall, the GSC type bushing may be delivered with a flange extension on the air side of the fastening flange to enable the bushing to pass through the wall to be indoor-immersed. These bushings are recognized by an “E” added to their denomination. For coordinating the design of the valve hall wall and transformer position with the bushing please refer to dimensions in Table 3.

StandardsThe GSC bushing is designed and tested according to IEC 60137 and IEC/IEEE 65700-19-03.

—Design

—01 Transformer bushing type GSC oil – air.

1. Outer terminal2. Top piece3. Composite insulator4. Test tap5. Mounting flange6. RIP core7. Bottom contact

4

5

3

1

7

2

6

6 TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E

—Table 1. General specificationsFor conditions exceeding the standard specification, such as in a HVDC valve hall, please consult the supplier.

Application: Transformers

Classification: Resin impregnated paper, capacitance graded, outdoor-immersed or indoor-immersed bushing, temperature class E (120 °C) according to IEC 60137

Ambient temperature: -40 °C to +40 °C for outdoor open air with maximum daily mean temperature +30 °C, unless otherwise specified.-10 °C to +60 °C for indoor valve hall ambient air (E series). See details in Table 2.

Altitude of site: < 1000 m. Bushings for other altitudes can be provided on request.

Level of rain and humidity: 1-2 mm rain/min. horizontally and vertically, as per IEC 60060-1, and 5 mm/min. as per IEEE

Pollution level: According to specific creepage distance and IEC 60815

Immersion medium: Transformer oil.Oil temperatures for normal load:Maximum daily mean temperature +90 °C. Maximum temporary temperature: +100 °C.

Max pressure of medium: 100 kPa (over pressure)

Angle of mounting: Horizontal to vertical

Test tap: Dimensions according to IEEE Potential tap type A. Ur = max. 600 V

Capacitance C2 of test tap: < 5000 pF

Conductor: Center tube conductor.

Markings: Conforming to IEC/IEEE.

Features and benefits• Solid (Oil free) – Reduced risk of fire. Oil leakage

from the bushing eliminated.• Seals the transformer – Reduced risk of fire.

Risk of oil leakage from the transformer reduced.

• Non-shattering materials – Silicone insulator. Protection of people and equipment.

• Easy handling – Safe transport - even when mounted on the transformer.

• Light weight, compact – Easy handling, small space requirements inside transformer, low life cycle environmental impact.

• Seismic qualified by shake table tests.

Transportation and long term storageOn the oil side of the bushing, a metallic sealing container, containing drying agent, is fitted. The sealing container will protect the oil side from moisture absorption. It is important that the sealing container is fitted during transport and storage. The container is suitable both for short-time storage (≤6 months) and long-time storage. The bushing can be stored outdoors when the sealing container is fitted.

TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E 7

—Testing

—02 Test tap.

—03 Test tap adapter.

Routine testingThe bushing is routine tested according to applicable standards including IEC/IEEE 65700-19-03 for DC applications.

The tests include measurement of partial discharge quantity, tan δ, capacitance, dry power frequency withstand, DC voltage withstand and polarity reversal test. The flange is separately tightness tested with helium. A visual inspection is performed and an individual routine test report is issued with each bushing.

Type testsComplete type tests have been performed and reports are available on request.

Test tapThe mounting flange is an aluminum alloy casting with the gasket surface machined flat. On the flange there is a test tap. The outer conducting layer of the condenser core is connected to the insulated test tap. During operation the protective cap must be fitted to ground the outer conducting layer to the flange. The maximum test voltage is 2 kV, 50 Hz for 1 minute. The maximum service voltage is 600 V.

Test tap adapterFor permanent connection of the test tap to measuring circuits, a test tap adapter is sometimes required, for example if the IEEE dimension standard for measuring tap is not used.

8 TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E

—Electrical data

—Table 2. Electrical data

Ratings GSC 200 200E 300 300E 4001) 400S 500 500E

Rated voltage only DC (phase-earth) (kV)Combined voltages evaluated on request. 280 280 340 340 385 450 500 500

Rated voltage only AC (phase-earth) (kV)Combined voltages evaluated on request. 209 209 242 242 318 400 420 430

Basic insulation level (kV)(Equal to dry lightning impulse withstand voltage.) 1050 1050 1175 1175 1675 1675 1800 1800

Dry switching impulse (kV) 850 850 950 950 1300 1300 1475 1475

Wet switching impulse (kV) 750 - 900 - 1300 1175 1425 -

Rated maximum continuous current (A)

Maximum ambient termperature (°C) 40 60 40 60 40 60 60 60

Maximum daily mean oil temperature (°C) 90 90 90 90 90 90 90 560

Frequency for rated current (Hz) 50-60 50-60 50-60 50-60 50-60 50 50 50

Al conductor 1600 1600 1500 1600

Cu conducor 3150 2200 2500 2100 2500 3000 3000 3000

Dry power frequency, routine test 1 min (kV) 506 506 560 560 750 750 750 750

Nominal capacitance between conductor and test tap C1 ± 10 % (pF) 600 819 640 821 612 648 799 915

Space for current transformer CT (mm) 400 400 600 600 600 600 600 600

DC withstand voltage 2 hours (kV) 405 405 620 620 770 882 930 930

Polarity reversal (kV) ±330 ±330 ±390 ±390 ±480 ±640 ±700 ±7001) GSC 400 is uprated; was previously delivered as GSB 250 HVDC bushing and GSC 250.

—Table 4. Dimensions.Dimensions are subject to modification without notice.

Type GSC Cat. No. Test tapRated current (A)

Dimensions Space for current transformer CT (mm)

Net mass (kg)

Creepage distance

L L1 L2 L3 L4 D1 D2 D3 D4 D5 D6 D7 Nominal Minimum

200 1ZSC905200-AAB 2 kV 1600 2740 2045 1345 340 195 372 446 274 335 535 400 450 600 400 8705 8355

1ZSC905200-BAB 2 kV 3150 2740 2045 1345 340 195 372 446 274 335 535 400 450 600 485 8705 8355

200E 1ZSC905200-HAB 2kV 2200 3418 2045 1345 1035 195 372 446 274 335 535 400 450 600 590 8705 8355

300 1ZSC905300-AAB 2 kV 1600 3920 3540 2860 340 195 376 480 300 335 560 450 500 600 550 12861 12345

1ZSC905300-BAB 2 kV 2500 3920 3540 2860 340 195 376 480 300 335 560 450 500 600 650 12861 12345

300E 1ZSC905300-HAB 2 kV 2100 4239 2860 1535 1040 195 376 480 300 335 560 450 500 600 845 12861 12345

400 1ZSC905500-AAB 2 kV 1600 4949 4230 1585 375 199 458 548 374 455 635 500 550 600 1010 19242 18755

1ZSC905500-BAB 2 kV 2500 4949 4230 1585 375 199 458 548 374 455 635 500 550 600 1148 19242 18755

400S 1ZSC905450-GCB 2 kV 3000 4562 3760 1955 417 220 568 663 459 580 780 740 711 600 1850 16650

500 1ZSC905500-CCB 2 kV 3000 5877 5100 1955 417 220 568 669 459 580 780 740 711 600 2250 20000

1ZSC905500-CDB 20 kV 3000 5877 5100 1955 417 220 568 669 459 580 780 740 711 600 2250 20000

500E 1ZSC905500-HCB 2 kV 3000 6577 5100 1955 1117 220 492 588 459 580 780 740 711 600 2550 7000

TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E 9

—Dimensions

—04 Dimensions. Standard type and with flange extension.

L4

D4

D1

L L1

D2

L3

CT

L2

Center holeØ 70

Ø 96

D3

D5

D6

Ø 23 (12x)M12

D7

—Table 4. Dimensions.Dimensions are subject to modification without notice.

Type GSC Cat. No. Test tapRated current (A)

Dimensions Space for current transformer CT (mm)

Net mass (kg)

Creepage distance

L L1 L2 L3 L4 D1 D2 D3 D4 D5 D6 D7 Nominal Minimum

200 1ZSC905200-AAB 2 kV 1600 2740 2045 1345 340 195 372 446 274 335 535 400 450 600 400 8705 8355

1ZSC905200-BAB 2 kV 3150 2740 2045 1345 340 195 372 446 274 335 535 400 450 600 485 8705 8355

200E 1ZSC905200-HAB 2kV 2200 3418 2045 1345 1035 195 372 446 274 335 535 400 450 600 590 8705 8355

300 1ZSC905300-AAB 2 kV 1600 3920 3540 2860 340 195 376 480 300 335 560 450 500 600 550 12861 12345

1ZSC905300-BAB 2 kV 2500 3920 3540 2860 340 195 376 480 300 335 560 450 500 600 650 12861 12345

300E 1ZSC905300-HAB 2 kV 2100 4239 2860 1535 1040 195 376 480 300 335 560 450 500 600 845 12861 12345

400 1ZSC905500-AAB 2 kV 1600 4949 4230 1585 375 199 458 548 374 455 635 500 550 600 1010 19242 18755

1ZSC905500-BAB 2 kV 2500 4949 4230 1585 375 199 458 548 374 455 635 500 550 600 1148 19242 18755

400S 1ZSC905450-GCB 2 kV 3000 4562 3760 1955 417 220 568 663 459 580 780 740 711 600 1850 16650

500 1ZSC905500-CCB 2 kV 3000 5877 5100 1955 417 220 568 669 459 580 780 740 711 600 2250 20000

1ZSC905500-CDB 20 kV 3000 5877 5100 1955 417 220 568 669 459 580 780 740 711 600 2250 20000

500E 1ZSC905500-HCB 2 kV 3000 6577 5100 1955 1117 220 492 588 459 580 780 740 711 600 2550 7000

R2 (2x)R5 (2x)

55

23.748

65

R8 (2x)

8°15°

L4

D4

L L1

D2

L3

CT

L2

Center holeØ 70

Ø 361

D3

10 TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E

—Connection details

—05 Outer terminal.

The outer terminal needs to be specified in each case.

Outer terminalThe terminal stud assembly consists of a cylindrical stud, a tightening ring, a sealing ring, gaskets, bolts, and washers. The electrical contact function and the sealing function are completely separated. The stud is first fastened to the bushing top with 6 bolts, M10, which provide the proper electrical contact. The contact surface is located inside the gasket and is thus well protected from corrosion. Finally, the tightening ring with the gasket is pressed against the stud by means of 6 additional bolts, M8.

The outer terminal is available in a number of standard configurations. Other configurations can be supplied on request.

—Table 2. Outer terminal. Max. torque on outer terminal 200 Nm.

Cat. No. Material Plating Stud diameter, D2 (mm)

1ZSC999010-AAA Aluminum - 60

1ZSC999010-AAB Copper - 60

1ZSC999010-AAC Copper - 80

End shielding of the outer terminal areaA separate outer shield for the air side is not always provided with the GSC bushing. The HVDC valve hall design with its bus-work and flexible conductors may call for shielding of the connecting pairs, but this should be resolved separately.

152.5

D2

125

TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E 11

Draw rod systemThe draw rod system offers the following advantages compared to other methods used for high currents:• No manholes required in the transformer tank.• The bushing tube is used as a conductor.• No special supports are required in the transformer, as is

the case with plug contacts.• Perfect guiding of the bushing into the transformer.

The center tube of the bushing is used as conductor. The transformer leads are fitted with cable lugs, bolted to a bottom contact. This contact is tightened to the lower end of the bushing tube by a steel draw rod. The upper end of this rod is bolted to a spring device, which consists of two concentric tubes of different materials, designed to give the required contact load at all temperatures. The draw rod is divided into two parts at level with the flange. The lower draw rod includes bottom contact, guide cone, rod and joint.

∅152.5

D2

125

L2

25

60

L5

64 45

M12 (4x)

Threaded hole M8 for pulling wire

H1 min 200

Additional joint on request

Bottom contact type 1(standard)

—06 Draw rod system.

The upper draw rod consists of compensating device, rods, joints, washer and nut.

If required to meet the transport conditions, an additional joint can be positioned at any desired level below the flange. This must be stated in the order. The lower part with contact and end-shield can then be secured to the transport cover during transport and storage of the transformer.

Bottom contacts with 4 threaded holes for cable lugs are available. The bottom contacts are made of copper in one piece. Special bottom contacts are available on request.

—Table 3. Draw rod system.

Cat. No. Type of draw rod

1ZSC999006 Lower draw rod

1ZSC999007 Upper draw rod

12 TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E

An oil side shield is not provided with the bushing. For operation under DC voltage it is a common procedure for the transformer manufacturer to arrange an external insulating system between the bushing condenser core and the grounded surfaces of the transformer. This external system is often referred to as a “barrier system” and is designed with a different type of transformer board or paper. The shielding of the bottom connection is a part of this external insulating system.

—End shielding of the bottom contact area

TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E 13

—Conductor loading and mechanical loading

Conductor loadingThe rated current of GSC bushings is of maximum continuous currents. No overload is permitted. The GSC is to be selected according to the required overload current of the transformer.

The short-time current capacity is calculated according to IEC 60137 and listed in Table 4.

Short-time currentThe rated thermal short-time current (Ith) is calculated according to IEC 60137.

—Table 4. Short-time current.

Type GSCRated currentA

Short-time current (Ith)kA, rms, 2 s

Dynamic current (Id)kA, peak

200 1600 40 100

3150 78 195

200E 1500 37 92

2200 55 137

300 1600 40 100

2500 62 155

300E 1500 37 92

2100 52 130

400 1600 40 100

2500 62 155

450S 3000 75 187

500 3000 75 187

500E 3000 75 187

Mechanical loadingThe cantilever operational and test loads are given in Table 5. The force is applied at the center of the outer terminal of the bushing. For extraordinary requirements, which include earthquakes, extreme environmental conditions and heavy equipment, consult the supplier. The tests comply with IEC 60137 and IEEE C57.19.00.

—Table 5. Mechanical loading.

Type GSB

Max. cantilever operating load for vertical mountingkN

Max. cantilever operating load for horizontal mountingkN

Max. cantilever test loadkN

200 3.2 2 6.3

200E 3.2 2 6.3

300 3.3 2 6.6

300E 3.3 2 6.6

400 6.5 4 13

400S 6.5 4 13

500 6.5 4 13

500E 6.5 4 13

14 TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E

—Recommendations for positioning

Bushing for AC applications are usually type tested and verified in an environment which defines distance to surrounding grounded surfaces together with suitable shielding.

For applications under DC voltage the positioning is governed by the surrounding insulating barriers and should be considered an integrated part. The details of the surrounding barrier and shielding are defined by the transformer manufacturer with guidance by the bushing supplier.

TR A N S FO R M E R B U S H I N G S T Y PE G S C TEC H N I C A L G U ID E 15

—Ordering particulars

When ordering, please state:• Type and catalog number for bushing.• Catalog number for draw rod, lower and upper part.• Catalog number for outer terminal.• Additional accessories or modifications.• Test required, in addition to the normal routine tests.

Ordering example:

Bushing: GSC 250/1600/0.6 Composite, test tap 1ZSC905200-AAB

Connection: Draw rod, lower, additional joint H = 300 mm 1ZSC999006

Draw rod, upper, bottom contact 1ZSC999007

Outer terminal: Copper, D2 = 60 mm 1ZSC999010-AAB

—ABB Power Grids Sweden AB, ComponentsSE-771 80 LudvikaSwedenE-mail: sales@se.abb.com

www.abb.com/transformercomponents

1ZS

C0

00

56

3-A

AW

en

, Rev

. 2, 2

020

-03

-30

© Copyright 2020 ABB. All rights reserved. Specifications subject to change without notice.