reflected-load-three-row-scan - Electronic Circuits XV: Transformers and Coupled Inductors Step by Step

Secondary load rows scan reflected resistance and primary load current. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Secondary load reflects through the turns ratio squared

The transformer row fixes the turns ratio, then the load row computes the primary equivalent.

R_p=R_s\left({N_p\over N_s}\right)^{2}

Three load rows scan resistance, current, and reflected load

The turns ratio stays fixed while the secondary load resistance changes.

\begin{array}{c|c|c|c}R_s&R_p&I_s&I_{p,\text{load}}\\3\ \text{ohm}&12\ \text{ohm}&2\ \text{A}&1\ \text{A}\\6\ \text{ohm}&24\ \text{ohm}&1\ \text{A}&\tfrac{1}{2}\ \text{A}\\12\ \text{ohm}&48\ \text{ohm}&\tfrac{1}{2}\ \text{A}&\tfrac{1}{4}\ \text{A}\\\end{array}

The reflected resistance is downstream of the transformer source

The accepted row binds load resistance, turns ratio, and primary load current.

R_p=3\ \text{ohm}\left({4\over2}\right)^{2}=12\ \text{ohm}