What is a dry-type transformer?

• A. An iron core, a primary coil, and a secondary coil
• B. A device that stores energy in a magnetic field
• C. A circuit component that transmits by code
• D. A sensor that detects smoke

Answer: (B)

A dry-type transformer is a transformer built with solid insulation instead of oil. Its defining features are an iron core plus a primary winding and a secondary winding arranged around that core. Energy moves from the input to the output through electromagnetic induction, with the magnetic flux looping through the iron core to link both windings. The solid insulation you see in dry-type transformers makes them safer for indoor use and reduces fire risk compared with oil-filled types.

Describing it as merely “a device that stores energy in a magnetic field” misses the main purpose, which is to transfer energy between circuits via the magnetic coupling of the windings. The other options reference functions or components that aren’t what a dry-type transformer is.