How many 60/400-Hz converters are present on a DD class ship?

The correct answer identifies that a DD class ship typically has three 60/400-Hz converters. These converters are essential for the operation of various systems on the ship, allowing the conversion of standard 60 Hz power to the 400 Hz frequency that certain equipment requires. This frequency is commonly used in aviation and military applications because it allows smaller and lighter electrical equipment, which is ideal for the constraints of naval vessels.

Having multiple converters ensures redundancy and reliability of the ship's electrical systems. If one converter were to fail, the other two could continue to supply power, maintaining operational integrity. This arrangement supports the ship's various operational needs, ensuring that critical systems remain functional.

In contrast, fewer converters would increase the risk of power loss if maintenance or failures occur, which is why three converters are the standard configuration in this class of ships.