Two power transformers, T1 and T2 are connected in parallel with their primary HV side connected...

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Two power transformers, T1 and T2 are connected in parallel with their primary HV side connected to the 110 kV bus and their LV side connected to the 11 kV bus. Tl nameplate data: 110Y/11A, 20 MVA, X=0.1 pu at neutral tap; T2 nameplate data: 110Y/11A, 12 MVA, X=0.08 pu at neutral tap; 30 MVA, 11 kV, 0.8 lagging p.f. Load: (a) Find the magnitude of the current in per unit through each transformer and the MVA output of each transformer. What problem do you detect? Can the problem be resolved by appropriate use of the tap-changing facilities? Justify your answer. The following tap settings are available on the high voltage side of both transformers: nominal, + 1.8%, + 3.6%. For your calculations, use a base of 30 MVA and 11 kV on the low voltage side. Assume that the load voltage is maintained at 11 kV. (b) The manufacturer of the transformers provided you with the following standard short-circuit test data ( test performed at neutral tap); For TI: Input Power =0.02 pu ; Short Circuit Current = 1 pu ; Input voltage = 0.102 pu For T2: Input Power=0.02 pu : Short Circuit Current = 1 pu ; Input voltage = 0.082 pu. Show how you would use that information to justify one of the main assumptions you have made in part (a). [No calculations required for this part. Hint: Base your answer on the equivalent circuit] The manufacturer of the transformers provided you with the following standard no- load test data ( test performed at neutral tap); For TI: Input Power = 0.02 pu ;no-load crurent =0.04 pu ;input voltage = I pu. (c) For T2: Input Power = 0.02 pu: Input Current = 0.04 pu ; Input voltage =1 pu. Show how you would use that information to justify one of the main assumptions you have made in part (a). [No calculations required for this part] Two power transformers, T1 and T2 are connected in parallel with their primary HV side connected to the 110 kV bus and their LV side connected to the 11 kV bus. Tl nameplate data: 110Y/11A, 20 MVA, X=0.1 pu at neutral tap; T2 nameplate data: 110Y/11A, 12 MVA, X=0.08 pu at neutral tap; 30 MVA, 11 kV, 0.8 lagging p.f. Load: (a) Find the magnitude of the current in per unit through each transformer and the MVA output of each transformer. What problem do you detect? Can the problem be resolved by appropriate use of the tap-changing facilities? Justify your answer. The following tap settings are available on the high voltage side of both transformers: nominal, + 1.8%, + 3.6%. For your calculations, use a base of 30 MVA and 11 kV on the low voltage side. Assume that the load voltage is maintained at 11 kV. (b) The manufacturer of the transformers provided you with the following standard short-circuit test data ( test performed at neutral tap); For TI: Input Power =0.02 pu ; Short Circuit Current = 1 pu ; Input voltage = 0.102 pu For T2: Input Power=0.02 pu : Short Circuit Current = 1 pu ; Input voltage = 0.082 pu. Show how you would use that information to justify one of the main assumptions you have made in part (a). [No calculations required for this part. Hint: Base your answer on the equivalent circuit] The manufacturer of the transformers provided you with the following standard no- load test data ( test performed at neutral tap); For TI: Input Power = 0.02 pu ;no-load crurent =0.04 pu ;input voltage = I pu. (c) For T2: Input Power = 0.02 pu: Input Current = 0.04 pu ; Input voltage =1 pu. Show how you would use that information to justify one of the main assumptions you have made in part (a). [No calculations required for this part]

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