Refer to page 30, the single line diagram shows 1000 kVA. if the transformer capacity rating to be used is 1500 kVA at 480 volts, and the second transformer rated 225 kVA be changed to 250 KVA at 208 volts, calculate the fault at X1 and fault at X2. Assume all other data are the same.

Power System Analysis and Design (MindTap Course List)
6th Edition
ISBN:9781305632134
Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma
Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma
Chapter7: Symmetrical Faults
Section: Chapter Questions
Problem 7.21MCQ
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Refer to page 30, the single line diagram shows 1000 kVA. if the transformer capacity rating to be used is 1500 kVA at 480 volts, and the second transformer rated 225 kVA be changed to 250 KVA at 208 volts, calculate the fault at X1 and fault at X2. Assume all other data are the same.

Point -to-point
Available
utility
400,000 SC KVA we
m
30-500 kcmil
& per phase Cu
in pvc conduit
Fault X
ONE LINE DIAGRAM
4600 switch
40A Fuse
20¹-2/0
a per phase Cu.
in PVC conduit wow
mm
1000 kVA x met
480v, 34,3.5%2
IfL = 1203 A
1600 A Switch
1600 A Fuse
225 KVA xmer
208V, 3-4
1-2%2
X₂
Page
Open with Google Docs
Fault XL
Step 1:
Multipler 100
1.2
5/5
IPL = 1000 x 1000 = 1203 A
480X1.732
Step@
Multiplier =
100
= 28.57
3.5
step Isc = 1202 x 28.57 = 34,370 A
step f
H
1-732 X30 x 34-370
4 x 26 704 x 480
=0.0348
Step M=1
= 0.09664
It 0.0348
Step Ise sum Rom 5² 34 370 x 0.09664
= 33215A
Fault X2
Step: f = 1.732 × 20 x 33 2415-
2 x 11423 x480
Hep: M = = 0.905
_!_
1+0.1049
Step : Ise Sun Rins
Fault X2
f=
M =
Iss sum RMS
30
Q +
-=0.1049
= 33215 x0.905
= 30099 A
30 049 x 480 x 1.732 x 1.2
100,000 x 225/
1.333
= 0.4286
1+ 1.333
= 480 X 0.4286 x 30059
208
= 29 731 A
1
762
Transcribed Image Text:Point -to-point Available utility 400,000 SC KVA we m 30-500 kcmil & per phase Cu in pvc conduit Fault X ONE LINE DIAGRAM 4600 switch 40A Fuse 20¹-2/0 a per phase Cu. in PVC conduit wow mm 1000 kVA x met 480v, 34,3.5%2 IfL = 1203 A 1600 A Switch 1600 A Fuse 225 KVA xmer 208V, 3-4 1-2%2 X₂ Page Open with Google Docs Fault XL Step 1: Multipler 100 1.2 5/5 IPL = 1000 x 1000 = 1203 A 480X1.732 Step@ Multiplier = 100 = 28.57 3.5 step Isc = 1202 x 28.57 = 34,370 A step f H 1-732 X30 x 34-370 4 x 26 704 x 480 =0.0348 Step M=1 = 0.09664 It 0.0348 Step Ise sum Rom 5² 34 370 x 0.09664 = 33215A Fault X2 Step: f = 1.732 × 20 x 33 2415- 2 x 11423 x480 Hep: M = = 0.905 _!_ 1+0.1049 Step : Ise Sun Rins Fault X2 f= M = Iss sum RMS 30 Q + -=0.1049 = 33215 x0.905 = 30099 A 30 049 x 480 x 1.732 x 1.2 100,000 x 225/ 1.333 = 0.4286 1+ 1.333 = 480 X 0.4286 x 30059 208 = 29 731 A 1 762
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