Transformer Efficiency by Editorial Staff Efficiency of a transformer is the ratio of the power output to the power input, as illustrated by Equation. where PS = power of secondary PP = power of primary Share With Your Friends Facebook Twitter LinkedIn Pinterest Email WhatsApp Don't Miss Our UpdatesBe the first to get exclusive content straight to your email. We promise not to spam you. You can unsubscribe at any time.Invalid email address You've successfully subscribed ! Recommended Articles Series and Parallel Inductors DC Machines Terminology Kirchhoff’s Laws Induction Motor DC Generator Internal Losses Three Phase Wattmeter AC Motor Theory Capacitance DC Generator Theory Losses in AC Generator