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A 25 kVA, 11 kV generator has X = 0.2 pu. Its negative and zero sequence reactance are respectively 0.3 and 0.1 pu. The neutral of the generator is solidly grounded. Determine the subtransient current in the generator and the line-to-line voltages for subtransient conditions when an LG fault occurs at the generator terminals. Assume that before the occurrence of the fault, the generator is operating at no load at rated voltage. Ignore resistances.?
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A 25 kVA, 11 kV generator has X = 0.2 pu. Its negative and zero sequen...
Subtransient Current in the Generator:

The subtransient current in the generator can be determined using the symmetrical components analysis. In this case, since an LG fault occurs at the generator terminals, we only need to consider the negative sequence component of the fault current.

The negative sequence reactance, X2, is given as 0.3 pu. The negative sequence current, I2, can be calculated using the formula:

I2 = (V2 / X2) * 100

where V2 is the negative sequence voltage. Since the fault occurs at the generator terminals, the negative sequence voltage is equal to the generator rated voltage, which is 11 kV.

Substituting the values, we get:

I2 = (11 kV / 0.3 pu) * 100 = 3666.67 A

Therefore, the subtransient current in the generator is 3666.67 A.

Line-to-Line Voltages for Subtransient Conditions:

The line-to-line voltages for subtransient conditions can be determined by considering the symmetrical components of the faulted system.

Positive Sequence Component:
Since the fault is a line-to-ground (LG) fault, the positive sequence voltage remains unchanged. Therefore, the line-to-line voltages for the positive sequence component will be the same as the pre-fault condition, which is the rated voltage of 11 kV.

Negative Sequence Component:
The negative sequence voltage, V2, can be calculated using the formula:

V2 = V1 * (-jX2)

where V1 is the positive sequence voltage and X2 is the negative sequence reactance. Substituting the values, we get:

V2 = 11 kV * (-j0.3 pu) = -3.3 kV

Therefore, the line-to-line voltages for the negative sequence component are as follows:

Vab = Vca = 11 kV
Vbc = Vba = 11 kV - 3.3 kV = 7.7 kV

Zero Sequence Component:
Since the neutral of the generator is solidly grounded, the zero sequence voltage is zero. Therefore, the line-to-line voltages for the zero sequence component are all zero.

To summarize, the line-to-line voltages for subtransient conditions when an LG fault occurs at the generator terminals are as follows:

Positive Sequence Component: 11 kV
Negative Sequence Component: Vab = Vca = 11 kV, Vbc = Vba = 7.7 kV
Zero Sequence Component: 0 kV
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A 25 kVA, 11 kV generator has X = 0.2 pu. Its negative and zero sequence reactance are respectively 0.3 and 0.1 pu. The neutral of the generator is solidly grounded. Determine the subtransient current in the generator and the line-to-line voltages for subtransient conditions when an LG fault occurs at the generator terminals. Assume that before the occurrence of the fault, the generator is operating at no load at rated voltage. Ignore resistances.?
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A 25 kVA, 11 kV generator has X = 0.2 pu. Its negative and zero sequence reactance are respectively 0.3 and 0.1 pu. The neutral of the generator is solidly grounded. Determine the subtransient current in the generator and the line-to-line voltages for subtransient conditions when an LG fault occurs at the generator terminals. Assume that before the occurrence of the fault, the generator is operating at no load at rated voltage. Ignore resistances.? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about A 25 kVA, 11 kV generator has X = 0.2 pu. Its negative and zero sequence reactance are respectively 0.3 and 0.1 pu. The neutral of the generator is solidly grounded. Determine the subtransient current in the generator and the line-to-line voltages for subtransient conditions when an LG fault occurs at the generator terminals. Assume that before the occurrence of the fault, the generator is operating at no load at rated voltage. Ignore resistances.? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A 25 kVA, 11 kV generator has X = 0.2 pu. Its negative and zero sequence reactance are respectively 0.3 and 0.1 pu. The neutral of the generator is solidly grounded. Determine the subtransient current in the generator and the line-to-line voltages for subtransient conditions when an LG fault occurs at the generator terminals. Assume that before the occurrence of the fault, the generator is operating at no load at rated voltage. Ignore resistances.?.
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