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228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7?
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228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (...
Solution:
Given parameters:
• Rating: 20 MVA
• High voltage (HV) side voltage: 220 kV (star)
• Low voltage (LV) side voltage: 33 kV (delta)
• Leakage reactance: 12%
We need to find the transformer reactance referred to each phase of the LV delta connected side.
Calculations:
Step 1: Calculate the HV phase voltage
V_phase = V_line / √3
V_phase = 220 / √3
V_phase = 127.0 kV
Step 2: Calculate the HV line current
I_line = S / (V_line * √3)
I_line = 20,000,000 / (220 * √3)
I_line = 59,415 A
Step 3: Calculate the HV phase current
I_phase = I_line / √3
I_phase = 59,415 / √3
I_phase = 34,342 A
Step 4: Calculate the HV phase impedance
Z_phase = V_phase / I_phase
Z_phase = 127.0 / 34,342
Z_phase = 3.69 Ω
Step 5: Calculate the HV phase reactance
X_phase = Z_phase * √(1 – leakage reactance^2)
X_phase = 3.69 * √(1 – 0.12^2)
X_phase = 3.38 Ω
Step 6: Calculate the LV phase voltage
V_phase = V_line / √3
V_phase = 33 / √3
V_phase = 19.1 kV
Step 7: Calculate the LV phase current
I_phase = I_line * √3
I_phase = 59,415 * √3
I_phase = 102,963 A
Step 8: Calculate the transformer impedance referred to LV side
Z_LV = Z_HV * (HV phase voltage / LV phase voltage)^2
Z_LV = X_phase * (220 / 33)^2
Z_LV = 19.6 Ω
Therefore, the transformer reactance referred to each phase of the LV delta connected side is 19.6 Ω.
Answer: (b) 19.6
Given parameters:
• Rating: 20 MVA
• High voltage (HV) side voltage: 220 kV (star)
• Low voltage (LV) side voltage: 33 kV (delta)
• Leakage reactance: 12%
We need to find the transformer reactance referred to each phase of the LV delta connected side.
Calculations:
Step 1: Calculate the HV phase voltage
V_phase = V_line / √3
V_phase = 220 / √3
V_phase = 127.0 kV
Step 2: Calculate the HV line current
I_line = S / (V_line * √3)
I_line = 20,000,000 / (220 * √3)
I_line = 59,415 A
Step 3: Calculate the HV phase current
I_phase = I_line / √3
I_phase = 59,415 / √3
I_phase = 34,342 A
Step 4: Calculate the HV phase impedance
Z_phase = V_phase / I_phase
Z_phase = 127.0 / 34,342
Z_phase = 3.69 Ω
Step 5: Calculate the HV phase reactance
X_phase = Z_phase * √(1 – leakage reactance^2)
X_phase = 3.69 * √(1 – 0.12^2)
X_phase = 3.38 Ω
Step 6: Calculate the LV phase voltage
V_phase = V_line / √3
V_phase = 33 / √3
V_phase = 19.1 kV
Step 7: Calculate the LV phase current
I_phase = I_line * √3
I_phase = 59,415 * √3
I_phase = 102,963 A
Step 8: Calculate the transformer impedance referred to LV side
Z_LV = Z_HV * (HV phase voltage / LV phase voltage)^2
Z_LV = X_phase * (220 / 33)^2
Z_LV = 19.6 Ω
Therefore, the transformer reactance referred to each phase of the LV delta connected side is 19.6 Ω.
Answer: (b) 19.6
Community Answer
228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (...
As Base impedance on LV side = (kv)^2/(MVA) = (33*10^3)2/20*10^6 = 54.45
Hence, Leakage Reactance in ohms (on LV side) = 54.45*0.12 = 6.534 ohms I.e. reactance per phase
In delta connection, if impedance in each arm is Z1, then per phase impedance (I.e. between phase and neutral) can be determine by converting to equivalent star
Zph=Z1/3 Hence, Z1= 3�Zph = 3�6.534 = 19.6 ohm
Hence, option (b)
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228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7?
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228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7? 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 228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for 228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7?.
228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7? 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 228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for 228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7?.
Solutions for 228. A 3-phase transformer has rating of 20 MVA, 220kV (star) -33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the lv delta connected side is (a) 23.5 (b) 19.6 (c) 18.5 (d) 8.7? in English & in Hindi are available as part of our courses for Electrical Engineering (EE).
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