7.5Kva distribution transformer operates as follows: full load and unity pf for 1.5hrs; half loaf for 1.5hrs with pf of 0.95 lagging; quarter load for 2.5hrs w/pf of 0.9 lagging. The losses are: iron loss is 100W and the full load copper loss is 113W. (a) solve for the full load efficiency in percent (b) solve for the output energy in kWh (c) solve for the energy loss in the copper winding in kWh. (d) solve for all-day efficiency in percent. (Take note 5 decimal places and box the final answer) Subject: Electrical Apparatus and Device

7.5Kva distribution transformer operates as follows: full load and unity pf for 1.5hrs; half loaf for 1.5hrs with pf of 0.95 lagging; quarter load for 2.5hrs w/pf of 0.9 lagging. The losses are: iron loss is 100W and the full load copper loss is 113W. (a) solve for the full load efficiency in percent (b) solve for the output energy in kWh (c) solve for the energy loss in the copper winding in kWh. (d) solve for all-day efficiency in percent. (Take note 5 decimal places and box the final answer) Subject: Electrical Apparatus and Device

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 3.32MCQ

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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.
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