1ZSC000563-AAW en Rev 1_språkgranskad.indd
1ZSC000563-AAW en, Rev. 1
Resin impregnated paper bushing, oil to air, type GSC Technical guide
Original instruction The 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. ABB makes no warranty or representation and assumes no liability of the accuracy of the information in this document or for the use of such information. All information in this document is subject to change without notice. This document must not be copied without our written permission, and the contents thereof must not be imparted to a third party nor be used for any unauthorized purpose. Contravention will be prosecuted.
Content Design........................................................................................................................ Features and benefits............................................................................................. Solid (Oil free). ..................................................................................................... Seals the transformer.......................................................................................... Silicone insulator................................................................................................. Easy handling. ..................................................................................................... Light weight, compact......................................................................................... Test tap.................................................................................................................. Test tap adapter..................................................................................................... Standards and testing............................................................................................. Standards........................................................................................................... Routine testing.................................................................................................... Type tests........................................................................................................... Transportation and storage..................................................................................... Long term storage...............................................................................................
5 5 5 5 5 5 5 6 6 6 6 6 6 6 6
Electrical data............................................................................................................. 7 General specifications. ............................................................................................ 7 Dimensions................................................................................................................. 8 Connection details....................................................................................................... Outer terminal........................................................................................................ Outer shield........................................................................................................... Draw rod system....................................................................................................
10 10 10 10
Conductor loading and mechanical loading................................................................... Conductor loading. ................................................................................................. Overloading of bushings according to IEC............................................................ Short-time current............................................................................................... Mechanical loading. ................................................................................................
13 13 13 13 13
Recommendations for positioning................................................................................. 14 Ordering particulars..................................................................................................... 15
Design
GSC is a Resin Impregnated Paper (RIP) bushing intended for immersed oil to air application. The bushing is manufactured by winding the condenser core onto the conductor tube, which is either aluminum or copper. The core consists of creped 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 a hollow core fiber reinforced tube with silicone rubber sheds provided with flanges at both ends.
Outer terminal Top piece
Air insulator, composite
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.
Condenser core
Several different studs are available for the air side connection and may be selected to properly interface to the relevant current clamp.
Bottom contact
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.
Test tap Mounting flange
Fig. 1. Transformer bushing type GSC oil – air.
The standard color of the composite insulator is ANSI 70 light gray. 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.
Silicone insulator Non-brittle material. 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.
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 5
Test tap The 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.
Standards and testing Standards The GSC bushing is designed and tested according to IEC 60137 and IEC/IEEE 65700-19-03. Routine testing The 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 tests Complete type tests have been performed and reports are available on request.
Fig. 2. Test tap.
Test tap adapter For 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.
Fig. 3. Test tap adapter.
6 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
Transportation and storage A metallic sealing tube containing drying agent is fitted on the oil side. This sealing tube will protect the bushing during transport. Long term storage Bushings for long term storage (>1 year) must be fitted with the enclosed metallic sealing tube.
Electrical data
Ratings GSC
200
300
400 2)
Rated voltage only DC (phase-earth) (kV)
280
300
385
209
240
318
Combined voltages evaluated on request. Rated voltage only AC peak (phase-earth) (kV) Combined voltages evaluated on request. Basic insulation level (kV)
1050
1175
1675
Dry switching impulse (kV)
750
950
1300 1300
Wet switching impulse (kV)
750
900
Rated current (A) Al/Cu 1)
1600/2000
1600/2000
1600/2000
Rated frequency (Hz)
50-60
50-60
50-60
Dry power frequency, routine test 1 min (kV)
506
560
750
Nominal capacitance between conductor and test tap C 1 ± 10 % (pF), with space for
600
640
612
current transformer CT = 600 mm DC withstand voltage 2 hours (kV)
405
620
770
Polarity reversal (kV)
±330
±390
±480
1) (Rated current (60 Hz), oil (daily mean 90 ºC) and air (daily mean 30 ºC) temp. acc. to IEC 60137) 2) GSC 400 is uprated; was previously delivered as GSB 250 HVDC bushing and GSC 250.
General specifications For conditions exceeding the standard specification below, such as in a HVDC valve hall, please consult the supplier. Application:
Transformers
Classification:
Resin impregnated paper, capacitance graded, outdoor immersed bushing, temperature class E (120 °C) acc. to IEC 60137
Ambient temperature:
+40 °C to -40 °C, minimum value acc. to temperature class 2 of IEC 60137
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:
Acc. to specific creepage distance and IEC 60815 ("Guide for selection of insulators with respect to polluted conditions")
Immersion medium:
Transformer oil. Oil temperatures for normal load: Maximum daily mean temperature +90 °C. Maximum temporary temperature: +100 °C. Oil temperatures for long and short time overload: Maximum daily mean temperature +90 °C. Maximum temporary temperature: +115 °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
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 7
Dimensions
Table 1. Dimensions (subject to modification without notice).
Type GSC 200
Cat. No.
Test tap
Rated current
Space for current
(A)
transformer CT (mm)
Net mass (kg)
Creepage distance Nominal
Minimum
1ZSC905200-AAB
2 kV
1600
600
400
8705
8355
1ZSC905200-BAB
2 kV
2000
600
485
8705
8355
GSC 300
1ZSC905300-AAB
2 kV
1600
600
550
12861
12345
1ZSC905300-BAB
2 kV
2000
600
650
12861
12345
GSC 400
1ZSC905500-AAB
2 kV
1600
600
1010
19242
18755
1ZSC905500-BAB
2 kV
2000
600
1148
19242
18755
Type
Cat. No.
Dimensions
GSC 200
1ZSC905200-AAB 1ZSC905200-BAB
2740
2045
1345
340
195
372
446
274
335
535
400
450
GSC 300
1ZSC905300-AAB
3920
3540
2860
340
195
376
480
300
335
560
450
500
1ZSC905300-BAB
3920
3540
2860
340
195
376
480
300
335
560
450
500
GSC 400
1ZSC905500-AAB
4949
4230
1585
375
199
458
548
374
455
635
500
550
1ZSC905500-BAB
4949
4230
1585
375
199
458
548
374
455
635
500
550
L
L1
L2
L3
L4
D1
D2
D3
D4
D5
D6
D7
2740
2045
1345
340
195
372
446
274
335
535
400
450
8 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
D4
L4
R5 (2x)
D1
15°
55 8°
48
R8 (2x)
L
23.7
65
B
L1
R2 (2x)
D5 D7 D2
D6 M12
Ø 23 (12x)
L3
CT
L2
Ø 70 * Ø 96 D3
* Center hole diameter
Fig. 4. Dimensions.
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 9
Connection details
The outer terminal needs to be specified in each case. Outer terminal The 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.
152.5
125
D2
Outer shield A 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. Draw rod system The 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 the 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 level with the flange. 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 can then be secured to the transport cover during transport and storage of the transformer.
Fig. 5. Outer terminal.
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
10 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
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
152.5 Threaded hole M8 for pulling wire
D2 125
L2
25
60 Additional joint on request 64 45
L5 H1 min 200
M12 (4x)
Bottom contact
Fig. 6. Draw rod system.
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 11
End shielding of the bottom contact area
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.
12 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
Conductor loading and mechanical loading
Conductor loading The GSC bushings fulfill the temperature rise test requirements according to IEC for the currents in the table below. The short-time current is also calculated according to IEC 60137 and listed in Table 6. Overloading of bushings according to IEC If the conductor for the bushing is selected with 120 % of the rated current of the transformer, the bushing is considered to be able to withstand the overload conditions stated in IEC 600076-7 when following the directions: for long time and short time emergency loading the oil temperature must be 115 °C max. and the daily mean oil temperature must be 90 °C max. For overload conditions other than IEC overload mentioned above, contact the supplier for permissible currents and temperatures.
Mechanical loading The 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.
Bushing Max. cantilever
Max. cantilever
Max. cantilever
GSC
operating load for
operating load for
test load
vertical mounting
horizontal mounting
kN
kN
kN
200
3.2
2
6.3
300
3.3
2
6.6
400
6.5
4
13
Short-time current The rated thermal short-time current (Ith) is calculated according to IEC 60137. Table 4. Short-time current.
Dynamic current
Bushing
Rated current
Short-time current
GSC
A
(I th)
(I d)
kA, rms, 2 s
kA, peak
200
1600/2000
10
100
300
1600/2000
10
100
400
1600/2000
10
100
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 13
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.
14 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
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,
1ZSC905500-AAB
test tap Connection:
Draw rod, lower, additional joint H 1ZSC999006 = 300 mm
Outer terminal:
Draw rod, upper, bottom contact
1ZSC999007
Copper, D2 = 60 mm
1ZSC999010-AAB
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 15
ABB AB Components SE-771 80 Ludvika, Sweden Phone: +46 240 78 20 00 Fax: +46 240 121 57 E-Mail: [email protected] www.abb.com/electricalcomponents
© Copyright 2015 ABB., All rights reserved. 1ZSC000563-AAW en, Rev. 1, 2015-03-15
Contact us
Resin impregnated paper bushing, oil to air, type GSC Technical guide
Original instruction The 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. ABB makes no warranty or representation and assumes no liability of the accuracy of the information in this document or for the use of such information. All information in this document is subject to change without notice. This document must not be copied without our written permission, and the contents thereof must not be imparted to a third party nor be used for any unauthorized purpose. Contravention will be prosecuted.
Content Design........................................................................................................................ Features and benefits............................................................................................. Solid (Oil free). ..................................................................................................... Seals the transformer.......................................................................................... Silicone insulator................................................................................................. Easy handling. ..................................................................................................... Light weight, compact......................................................................................... Test tap.................................................................................................................. Test tap adapter..................................................................................................... Standards and testing............................................................................................. Standards........................................................................................................... Routine testing.................................................................................................... Type tests........................................................................................................... Transportation and storage..................................................................................... Long term storage...............................................................................................
5 5 5 5 5 5 5 6 6 6 6 6 6 6 6
Electrical data............................................................................................................. 7 General specifications. ............................................................................................ 7 Dimensions................................................................................................................. 8 Connection details....................................................................................................... Outer terminal........................................................................................................ Outer shield........................................................................................................... Draw rod system....................................................................................................
10 10 10 10
Conductor loading and mechanical loading................................................................... Conductor loading. ................................................................................................. Overloading of bushings according to IEC............................................................ Short-time current............................................................................................... Mechanical loading. ................................................................................................
13 13 13 13 13
Recommendations for positioning................................................................................. 14 Ordering particulars..................................................................................................... 15
Design
GSC is a Resin Impregnated Paper (RIP) bushing intended for immersed oil to air application. The bushing is manufactured by winding the condenser core onto the conductor tube, which is either aluminum or copper. The core consists of creped 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 a hollow core fiber reinforced tube with silicone rubber sheds provided with flanges at both ends.
Outer terminal Top piece
Air insulator, composite
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.
Condenser core
Several different studs are available for the air side connection and may be selected to properly interface to the relevant current clamp.
Bottom contact
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.
Test tap Mounting flange
Fig. 1. Transformer bushing type GSC oil – air.
The standard color of the composite insulator is ANSI 70 light gray. 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.
Silicone insulator Non-brittle material. 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.
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 5
Test tap The 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.
Standards and testing Standards The GSC bushing is designed and tested according to IEC 60137 and IEC/IEEE 65700-19-03. Routine testing The 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 tests Complete type tests have been performed and reports are available on request.
Fig. 2. Test tap.
Test tap adapter For 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.
Fig. 3. Test tap adapter.
6 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
Transportation and storage A metallic sealing tube containing drying agent is fitted on the oil side. This sealing tube will protect the bushing during transport. Long term storage Bushings for long term storage (>1 year) must be fitted with the enclosed metallic sealing tube.
Electrical data
Ratings GSC
200
300
400 2)
Rated voltage only DC (phase-earth) (kV)
280
300
385
209
240
318
Combined voltages evaluated on request. Rated voltage only AC peak (phase-earth) (kV) Combined voltages evaluated on request. Basic insulation level (kV)
1050
1175
1675
Dry switching impulse (kV)
750
950
1300 1300
Wet switching impulse (kV)
750
900
Rated current (A) Al/Cu 1)
1600/2000
1600/2000
1600/2000
Rated frequency (Hz)
50-60
50-60
50-60
Dry power frequency, routine test 1 min (kV)
506
560
750
Nominal capacitance between conductor and test tap C 1 ± 10 % (pF), with space for
600
640
612
current transformer CT = 600 mm DC withstand voltage 2 hours (kV)
405
620
770
Polarity reversal (kV)
±330
±390
±480
1) (Rated current (60 Hz), oil (daily mean 90 ºC) and air (daily mean 30 ºC) temp. acc. to IEC 60137) 2) GSC 400 is uprated; was previously delivered as GSB 250 HVDC bushing and GSC 250.
General specifications For conditions exceeding the standard specification below, such as in a HVDC valve hall, please consult the supplier. Application:
Transformers
Classification:
Resin impregnated paper, capacitance graded, outdoor immersed bushing, temperature class E (120 °C) acc. to IEC 60137
Ambient temperature:
+40 °C to -40 °C, minimum value acc. to temperature class 2 of IEC 60137
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:
Acc. to specific creepage distance and IEC 60815 ("Guide for selection of insulators with respect to polluted conditions")
Immersion medium:
Transformer oil. Oil temperatures for normal load: Maximum daily mean temperature +90 °C. Maximum temporary temperature: +100 °C. Oil temperatures for long and short time overload: Maximum daily mean temperature +90 °C. Maximum temporary temperature: +115 °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
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 7
Dimensions
Table 1. Dimensions (subject to modification without notice).
Type GSC 200
Cat. No.
Test tap
Rated current
Space for current
(A)
transformer CT (mm)
Net mass (kg)
Creepage distance Nominal
Minimum
1ZSC905200-AAB
2 kV
1600
600
400
8705
8355
1ZSC905200-BAB
2 kV
2000
600
485
8705
8355
GSC 300
1ZSC905300-AAB
2 kV
1600
600
550
12861
12345
1ZSC905300-BAB
2 kV
2000
600
650
12861
12345
GSC 400
1ZSC905500-AAB
2 kV
1600
600
1010
19242
18755
1ZSC905500-BAB
2 kV
2000
600
1148
19242
18755
Type
Cat. No.
Dimensions
GSC 200
1ZSC905200-AAB 1ZSC905200-BAB
2740
2045
1345
340
195
372
446
274
335
535
400
450
GSC 300
1ZSC905300-AAB
3920
3540
2860
340
195
376
480
300
335
560
450
500
1ZSC905300-BAB
3920
3540
2860
340
195
376
480
300
335
560
450
500
GSC 400
1ZSC905500-AAB
4949
4230
1585
375
199
458
548
374
455
635
500
550
1ZSC905500-BAB
4949
4230
1585
375
199
458
548
374
455
635
500
550
L
L1
L2
L3
L4
D1
D2
D3
D4
D5
D6
D7
2740
2045
1345
340
195
372
446
274
335
535
400
450
8 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
D4
L4
R5 (2x)
D1
15°
55 8°
48
R8 (2x)
L
23.7
65
B
L1
R2 (2x)
D5 D7 D2
D6 M12
Ø 23 (12x)
L3
CT
L2
Ø 70 * Ø 96 D3
* Center hole diameter
Fig. 4. Dimensions.
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 9
Connection details
The outer terminal needs to be specified in each case. Outer terminal The 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.
152.5
125
D2
Outer shield A 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. Draw rod system The 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 the 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 level with the flange. 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 can then be secured to the transport cover during transport and storage of the transformer.
Fig. 5. Outer terminal.
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
10 Technical guide GSC | 1ZSC000563-AAW en, Rev. 1
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
152.5 Threaded hole M8 for pulling wire
D2 125
L2
25
60 Additional joint on request 64 45
L5 H1 min 200
M12 (4x)
Bottom contact
Fig. 6. Draw rod system.
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 11
End shielding of the bottom contact area
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.
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Conductor loading and mechanical loading
Conductor loading The GSC bushings fulfill the temperature rise test requirements according to IEC for the currents in the table below. The short-time current is also calculated according to IEC 60137 and listed in Table 6. Overloading of bushings according to IEC If the conductor for the bushing is selected with 120 % of the rated current of the transformer, the bushing is considered to be able to withstand the overload conditions stated in IEC 600076-7 when following the directions: for long time and short time emergency loading the oil temperature must be 115 °C max. and the daily mean oil temperature must be 90 °C max. For overload conditions other than IEC overload mentioned above, contact the supplier for permissible currents and temperatures.
Mechanical loading The 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.
Bushing Max. cantilever
Max. cantilever
Max. cantilever
GSC
operating load for
operating load for
test load
vertical mounting
horizontal mounting
kN
kN
kN
200
3.2
2
6.3
300
3.3
2
6.6
400
6.5
4
13
Short-time current The rated thermal short-time current (Ith) is calculated according to IEC 60137. Table 4. Short-time current.
Dynamic current
Bushing
Rated current
Short-time current
GSC
A
(I th)
(I d)
kA, rms, 2 s
kA, peak
200
1600/2000
10
100
300
1600/2000
10
100
400
1600/2000
10
100
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 13
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.
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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,
1ZSC905500-AAB
test tap Connection:
Draw rod, lower, additional joint H 1ZSC999006 = 300 mm
Outer terminal:
Draw rod, upper, bottom contact
1ZSC999007
Copper, D2 = 60 mm
1ZSC999010-AAB
1ZSC000563-AAW en, Rev. 1 | Technical guide GSC 15
ABB AB Components SE-771 80 Ludvika, Sweden Phone: +46 240 78 20 00 Fax: +46 240 121 57 E-Mail: [email protected] www.abb.com/electricalcomponents
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