Final answer:
Large dry-type distribution-type transformer enclosures have steel bottoms that are punched for ventilation purposes.
Step-by-step explanation:
Large dry-type distribution-type transformer enclosures have steel bottoms that are punched for specific purposes such as ventilation.
This punching allows for air flow inside the enclosure, preventing overheating and ensuring the proper operation of the transformer. Without proper ventilation, heat generated by the transformer could build up, causing damage or malfunctions.
By punching holes in the steel bottoms of the enclosure, air can freely circulate, dissipating heat and maintaining a safe operating temperature for the transformer.