Is the voltage applied to the primary winding of a distribution transformer usually higher than the voltage induced in the secondary winding?

• A. False
• B. True
• C. Sometimes higher, sometimes lower
• D. Not necessarily related

Answer: (B)

Voltage transfer in a transformer follows the turns ratio: the voltage on the secondary is determined by how many turns the secondary winding has compared to the primary. A distribution transformer is designed to take a high distribution voltage on the primary and step it down to a lower voltage on the secondary. Because it’s a step-down arrangement, the primary has more turns than the secondary, so the induced secondary voltage is lower than the applied primary voltage. The relationship is Vs = Vp × (Ns/Np), with Ns < Np in a typical distribution transformer. That’s why the voltage applied to the primary winding is usually higher than the voltage induced in the secondary. Only in step-up or special transformer configurations would the secondary voltage be higher.