0195136047.pdf

504 MAGNETIC CIRCUITS AND TRANSFORMERS

former to step up voltage from 220 V to 2420

V. Without exceeding the rated current of any

winding, determine the kVA rating of the auto-

transformer, the kVA transformed by transformer

action, and the kVA conducted.

11.6.6A 5-kVA, 480:120-V, two-winding, 60-Hz,

single-phase transformer has an efficiency of

95% while delivering rated load at rated voltage

and 0.8 power factor lagging. This transformer

is to be connected as an autotransformer to step

down a 600-V source to 480 V.

(a) Draw a schematic connection diagram as an

autotransformer.

(b) Find the maximum kVA rating as an auto-

transformer.

(c) Compute the efficiency as an autotrans-

former delivering its rated kVA at 480 V and

0.8 power factor lagging.