GATE EE 2014 Set 2 — Question 53
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Power Systems → Fault Analysis → Fault Current Calculation
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Question
A three phase, MVA, kV generator has solidly grounded neutral. The positive, negative, and the zero sequence reactances of the generator are pu, pu, and pu, respectively, at the machine base quantities. If a bolted single phase to ground fault occurs at the terminal of the unloaded generator, the fault current in amperes immediately after the fault is _________.
Correct answer
15300 to 15500
Solution
Given data:
Base Power, MVA
Base Voltage, kV
Positive sequence reactance, pu
Negative sequence reactance, pu
Zero sequence reactance, puStep 1: Calculate the base current ():Step 2: Calculate the fault current in per unit () for a bolted single line to ground (SLG) fault:
For an unloaded generator, assuming pre-fault voltage pu:Step 3: Calculate the fault current in Amperes ():The fault current is approximately A, which falls within the range of to .
Base Power, MVA
Base Voltage, kV
Positive sequence reactance, pu
Negative sequence reactance, pu
Zero sequence reactance, puStep 1: Calculate the base current ():Step 2: Calculate the fault current in per unit () for a bolted single line to ground (SLG) fault:
For an unloaded generator, assuming pre-fault voltage pu:Step 3: Calculate the fault current in Amperes ():The fault current is approximately A, which falls within the range of to .
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