Example: Step Down Transformer

Problem Statement

Given a 48 kVA, 480/240 V/V step down transformer operating at rated load with a power factor of 0.7 (lag), determine the efficiency and voltage regulation.

Given: $R_L=0.2\mathrm{\Omega },X_L=0.6\mathrm{\Omega },R_H=0.8\mathrm{\Omega },X_H=1.6\mathrm{\Omega },R_{cH}=3.2k\mathrm{\Omega },H_{cH}=1.2k\mathrm{\Omega }$

• this problem is from EMEC EXAM 1, Winter 08 by legendary Dr. Cross