DESIGN CALCULATIONS FOR DESIGN OF 1.1 kV, 5000A LT BUSDUCT
PROJECT:
Customer: Consultant: Contractor:
Page 1 of 5
Contents: 1.
Design Parameters
2.
Thermal Withstand Capability
Page 2 of 5
DESIGN OF SPB Design parameters 1
Nominal System Voltage
-
0.415 kV
2
Rated Voltage
-
1.1 kV
3
BIL Rating.
-
4
Encl. Dimension
- 1000 mm x 700 mm
5
Encl. Material
-
6
Encl. Material Thk.
-
3 mm
7
Busbar Material
-
Aluminium
8
Busbar Size
-
200 x 12 – 4runs Per PH.
9
Cross Sectional Area
-
9600Sq. mm
10 Short Circuit Current(Isc)
-
50 kA.
2.5
Aluminium
11 Duration of Short Circuit(T)
-
1 Sec.
12 Momentary Peak Withstand Current
-
110 kAp
13 Design Ambient Temperature
-
500 C
14 Hot spot temperature of Conductor Carrying Rated Current
-
400 C
15 Hot spot temperature of Enclosure
700 C
-
16 Max. Temperature Rise of Conductor during fault condition While carrying rated current 17 Rated Current
- 2500 C Over design ambient temperature -
5000 A
Page 3 of 5
Thermal Withstand Capability Continuos Current Rating Derating Factors: Conductor to Enclosure ratio (1.3 %)
-
0.875
Temperature Rise of 400 C Rise above 50 0 C Ambient
-
0.815
Proximity effect
-
0.95
Black-Matt finish
-
1.2
Non Magnetic Enclosure
-
Total De-rating factor
1.0 -
0.81
AC Current rating of bare ( unpainted ) busbar in still but unconfined air for a Temperature rise of 35 0 C over an ambient of 50 0 C. = 6150 A For Interleaving Design = 1.18 x 6150 = 7257 A ∴ Rating of busbar for above size conductor =
