A 10 KVA, 120/600 V, 60 Hz, single- phase transformer is tested with the following results: Find the impedance referred to the LVS of the transformer. Short-circuit test (measured from High-voltage side ) Vsc= 20 V Isc= 16.67 A Psc= 90 W Select one: O a. Rc.p = 0.81 Q, and XM,p = 2.9 b. None c. Reg, p = 8.1N, and Xeq,p = 29 d. Reg,s = 8.1 2, and Xeq,s = 2.9 K

A 10 KVA, 120/600 V, 60 Hz, single- phase transformer is tested with the following results: Find the impedance referred to the LVS of the transformer. Short-circuit test (measured from High-voltage side ) Vsc= 20 V Isc= 16.67 A Psc= 90 W Select one: O a. Rc.p = 0.81 Q, and XM,p = 2.9 b. None c. Reg, p = 8.1N, and Xeq,p = 29 d. Reg,s = 8.1 2, and Xeq,s = 2.9 K

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter28: Three-phase Transformers

Section: Chapter Questions

Problem 4RQ: An open-delta three-phase transformer system has one transformer center-tapped to provide a neutral...

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An infinite bus, which is a constant voltage source, is connected to the primary of the three-winding transformer of Problem 3.53. A 7.5-MVA,13.2-kV synchronous motor with a sub transient reactance of 0.2 per unit is connected to the transformer secondary. A5-MW,2.3-kV three-phase resistive load is connected to the tertiary Choosing a base of 66 kV and 15 MVA in the primary, draw the impedance diagram of the system showing per-unit impedances. Neglect transformer exciting current, phase shifts, and all resistances except the resistive load.
The ratings of a three-phase three-winding transformer are Primary(1): Y connected 66kV,15MVA Secondary (2): Y connected, 13.2kV,10MVA Tertiary (3): A connected, 2.3kV,5MVA Neglecting winding resistances and exciting current, the per-unit leakage reactances are X12=0.08 on a 15-MVA,66-kV base X13=0.10 on a 15-MVA,66-kV base X23=0.09 on a 10-MVA,13.2-kV base (a) Determine the per-unit reactances X1,X2,X3 of the equivalent circuit on a 15-MVA,66-kV base at the primary terminals. (b) Purely resistive loads of 7.5 MW at 13.2 kV and 5 MW at 2.3kV are connected to the secondary and tertiary sides of the transformer, respectively. Draw the per- unit impedance diagram, showing the per-unit impedances on a 15-MVA,66-kV base at the primary terminals.
A single-phase step-down transformer is rated 13MVA,66kV/11.5kV. With the 11.5 kV winding short-circuited, rated current flows when the voltage applied to the primary is 5.5 kV. The power input is read as 100 kW. Determine Req1andXeq1 in ohms referred to the high-voltage winding.
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Rework Problem 3.14 if the transformer is delivering rated load at rated secondary voltage and at (a) unity power factor, (b) 0.8 power factor leading. Compare the results with those of Problem 3.14. -
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