A 250kVA single phase transformer has an iron loss of 2kW and the maximum efficiency at 0.8 P.F occurs when the load is 150kW, calculate 1- the maximum efficiency at unity P.F. 2- the efficiency on full-load at 0.707 P.F.

A 250kVA single phase transformer has an iron loss of 2kW and the maximum efficiency at 0.8 P.F occurs when the load is 150kW, calculate 1- the maximum efficiency at unity P.F. 2- the efficiency on full-load at 0.707 P.F.

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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Concept explainers

Distribution System

The final stage in the delivery of the electric power is the electric power distribution system. From the transmission system to the individual customers it carries electricity. The distribution system is connected with the transmission system and is used to lower the voltage of the transmission to medium voltage in the range of 2 kV to 35 kV with the help of transformers. This medium voltage to the distribution transformers located near the customer's premises is carried by the primary distribution system lines. These distribution transformers in turn lower the voltage to utilization voltage used in lightings, household appliances, industrial equipments etc. Through secondary distribution lines often several customers are supplied from one transformer. It is through service drops, the commercial and residential customers are connected to the secondary distribution system lines. Customers who demand a larger amount of power can be connected directly to the primary distribution system level or the sub-transmission level.

Question

A 250kVA single phase transformer has an iron loss of 2kW and the maximum
efficiency at 0.8 P.F occurs when the load is 150kW, calculate
1- the maximum efficiency at unity P.F.
2- the efficiency on full-load at 0.707 P.F.

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