What type of power is applied to the controller for the drain masts to heat?

The type of power applied to the controller for the drain masts to heat is 115V AC power. This is the standard voltage used for heating elements in aircraft systems, including those in the CRJ550. The drain masts heat feature is essential for preventing ice formation, which can negatively affect aircraft performance and safety.

Using 115V AC ensures that the heating elements receive consistent and effective power for their operation. This voltage level is commonly found in various aircraft systems, providing compatibility with other electrical components and systems.

The options representing DC power and 220V AC power refer to different applications and are not typically used for heating systems designed for functions like the drain masts. Ground power, while relevant in a different context, specifically pertains to the external electrical power supply when the aircraft is on the ground and does not directly relate to the heating of drain masts.