ABB GSB 420 Manuel technique - Page 16

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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 B T E C H N I C A L G U I D E
—
Conductor loading and mechanical
loading

Conductor loading

The GSB 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 acc. 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 60076-7 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 above mentioned IEC
overload, contact the supplier for permissible currents and
temperatures.
Short-time current
The rated thermal short-time current (I
according to IEC 60137.
—
Table 9. Short-time current.
Rated current
Type GSB
A
245
2000
3150
362
1600
3150
420
1600
2500
550
1600
2500
) is calculated
th
Short-time
Dynamic
current (I
)
current (I
)
th
d
kA, rms, 2 s
kA, peak
100
250
100
250
100
250
100
250
100
250
100
250
100
250
100
250

Mechanical loading

The cantilever operational and test loads are given in Table 7.
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 are performed in
accordance with IEC 60137 and IEEE C57.19.00. All cantilever
loads exceed IEC 60137 Level II and IEEE C57.19.01-2000.
—
Table 10. Mechanical loading.
Max. cantilever
operating load
for vertical
mounting
Type GSB
kN
245
2.8
362
6.0
420
6.5
550
6.5
Max. cantilever
operating load
for horizontal
Max. cantilever
mounting
test load
kN
kN
2
5.6
4
12
4
13
4
13