5) A 160 MVA, 132/66 kV, DY-1, 3-phase transformer is to be protected against short- circuit using instantaneous overcurrent relay. Rated current of transformer on 132 kV side is 699.82 A. The magnetizing inrush current of the transformer is 8 times the rated current. The setting range of an instantaneous overcurrent relay is 400-2000% of 1 A in step of 50%. The CT ratio is 1000/1 A. The setting of an instantaneous overcurrent relay is 450% 500% 550% 600%

5) A 160 MVA, 132/66 kV, DY-1, 3-phase transformer is to be protected against short- circuit using instantaneous overcurrent relay. Rated current of transformer on 132 kV side is 699.82 A. The magnetizing inrush current of the transformer is 8 times the rated current. The setting range of an instantaneous overcurrent relay is 400-2000% of 1 A in step of 50%. The CT ratio is 1000/1 A. The setting of an instantaneous overcurrent relay is 450% 500% 550% 600%

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

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.27MCQ

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Similar questions

The ratings of a three-phase, three-winding transformer are Primary: Y connected, 66kV,15MVA Secondary: Y connected, 13.2kV,10MVA Tertiary: connected, 2.3kV,5MVA Neglecting resistances and exciting current, the leakage reactances are: XPS=0.09 per unit on a 15-MVA,66-kV base XPT=0.08 per unit on a 15-MVA,66-kV base XST=0.05 per unit on a 10-MVA,13.2-kV base Determine the per-unit reactances of the per-phase equivalent circuit using a base of 15 MVA and 66 kV for the primary.
Three single-phase, two-winding transformers, each rated 450MVA,20kV/288.7kV, with leakage reactance Xeq=0.10perunit, are connected to form a three-phase bank. The high-voltage windings are connected in Y with a solidly grounded neutral. Draw the per-unit equivalent circuit if the low-voltage windings are connected (a) in with American standard phase shift or (b) in Y with an open neutral. Use the transformer ratings as base quantities. Winding resistances and exciting current are neglected.
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Two generators are connected in parallel to the low voltage side of a transformer. Generators G1 and G 2 are each rated at 50 MVA, 13.8 kV, with a subtransient resistance of 0.2 pu. Transformer T1 is rated at 100 MVA, 13.8/115 kV with a series reactance of 0.08 pu and negligible resistance. Assume that initially the voltage on the high side of the transformer is 120 kV, that the transformer is unloaded, and that there are no circulating currents between the generators. Calculate the subtransient fault current that will flow if a 3 phase fault occurs at the high-voltage side of transformer AY Gz ratings: 50 MVA G, ratings: số MVA 13.8 KV X" = 0.20 pu T, ratings: 100 MVA 13.8/113 V X - 0.08 pu 13.8 KV X" - 0.20 pu Choose the per-unit base values for this power system to be 100 MVA and 13.8 kV