Conductor Loading; Overloading Of Bushings; Short-Time Current - ABB GSA-OO Technical Manual

12 T R A N S F O R M E R B U S H I N G S T Y P E G S A - O O T E C H N I C A L G U I D E
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Conductor loading

The GSA-OO bushings is heat run tested with solid
conductors and 1200 mm
2
together with calculated values for different stranded
cables are given in the table below:
Table 6.
Bushing Conductor
LF 135 073 Solid rod ø 58 mm
Stranded cable
1200 mm
2
900 mm 2
450 mm
2
150 mm
2
LF 135 123 Solid rod ø 58 mm
Stranded cable
1200 mm
2
900 mm
2
450 mm 2
150 mm 2
LF 135 145 Solid rod ø 58 mm
Stranded cable
1200 mm 2
900 mm
2
450 mm
2
150 mm
2
LF 135 170 Solid rod ø 58 mm
Stranded cable
1200 mm
2
900 mm
2
450 mm 2
150 mm
2
LF 135 245 Solid rod ø 58 mm
Stranded cable
1200 mm 2
900 mm
2
450 mm
2
150 mm 2
stranded cable. The test currents
Tested permissible
Calculated
current
permissible
IEC IEEE current
A A A
2500 2500
2000 2000
1500
1000
500
2000 2000
1600 1600
1200
850
450
2000 2000
1600 1600
1200
850
450
2000 2000
1600 1600
1200
850
450
1600 1600
1250 1250
950
650
350

Overloading of bushings

If the conductor for the bushing is selected for 120 % of the
rated current of the transformer, the bushing is considered
to be able to withstand the overload conditions stated in
IEC 60076-7 without further clarifications or tests,
according to IEC 60137.

Short-time current

The rated thermal short-time current (I
according to IEC 60137.
Table 7.
Rated
current Area
Conductor A mm
2
Solid rod
Ø 58 mm 2500.. 1600 2642
Stranded
draw-lead 2000.. 1250 1200
) is calculated
th
Short-time current (I )
Dynamic
th
kA, rms
current (I
1 s 2 s kA, peak
100 100 315
89 63 157
)
d