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: $R_{L}~=~0.2~\Omega ,~~X_{L}~=~0.6~\Omega ,~~R_{H}~=~0.8~\Omega ,~~X_{H}~=~1.6~\Omega ,~~R_{cH}~=~3.2~k\Omega ,~~X_{mH}~=~1.2~k\Omega$

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

Solution

From the given data of the step down transformer we can see that Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \text a=2~and~s=48000~\angle cos^{-1} \}