Voltage Step-Down Transformer

This is problem 5-9 from Electric Drives: An Integrative Approach by Ned Mohan, Published 2003 by MNPERE.

Problem Statement

A transformer is designed to step down the applied voltage of 120 V (rms) to 24 V (rms) at 60 Hz. Calculate the maximum rms voltage that can be applied to the high-side of this transformer without exceeding the rated flux density in the core if this transformer is used in a power system with a frequency of 50 Hz.

Solution

The first bit of information we can get from this example is the ratio of N1 to N2, which is simply 120/24, which simplifies to 5/1. Since we are not given the rated flux density of the core, we will represent it as the constant B.