Which component is essential to a dry-type transformer?

• A. External circuit breaker
• B. Iron core
• C. Liquid coolant
• D. Sensor

Answer: (B)

A transformer operates by transferring energy through a closed magnetic path, which requires a material with high magnetic permeability to guide the flux efficiently. The iron core provides this low-reluctance path, surrounding the windings so the alternating current in the primary induces voltage in the secondary with minimal loss. In a dry-type transformer, the windings are supported by and around this laminated iron core, and no liquid coolant is used—cooling is typically via air. Protective devices like circuit breakers or any sensors may be present for safety and monitoring, but they aren’t what enables the transformer to function. The core is the essential element that makes the transformer work.