What is the difference between DC electrical power and AC electrical power in aircraft systems?

What is the difference between DC electrical power and AC electrical power in aircraft systems?

• A. DC powers controls and sensors with steady voltage; AC powers motors and avionics with alternating current, often at higher frequency.
• B. DC powers only lighting; AC powers only flight instruments.
• C. DC is always higher voltage than AC in aircraft systems.
• D. AC powers controls and sensors with steady voltage; DC powers motors with pulsating current.

Answer: (A)

The main idea is that the electrical power design in aircraft uses different current types for different kinds of loads based on stability and power needs. DC provides a steady, unidirectional voltage ideal for controls and sensors where precision and low noise are crucial. That stable voltage keeps flight-control computers, transducers, and other sensing electronics operating reliably without the fluctuations that can come with alternating current. AC, on the other hand, is used where more power is required or where components are designed to run on alternating current. Motors, actuators, and many avionics power devices are fed from AC because these loads can efficiently handle AC power, and aircraft systems often employ higher-frequency AC (such as 400 Hz). The higher frequency helps reduce the size and weight of transformers and motors, which is a significant advantage in aviation. So, the statement matches how DC powers the controls and sensors with a steady voltage, while AC powers higher‑power components like motors and certain avionics, often at higher frequency. The other options mix up which loads use DC versus AC, or make incorrect claims about voltage and pulsating current.

The main idea is that the electrical power design in aircraft uses different current types for different kinds of loads based on stability and power needs. DC provides a steady, unidirectional voltage ideal for controls and sensors where precision and low noise are crucial. That stable voltage keeps flight-control computers, transducers, and other sensing electronics operating reliably without the fluctuations that can come with alternating current.

AC, on the other hand, is used where more power is required or where components are designed to run on alternating current. Motors, actuators, and many avionics power devices are fed from AC because these loads can efficiently handle AC power, and aircraft systems often employ higher-frequency AC (such as 400 Hz). The higher frequency helps reduce the size and weight of transformers and motors, which is a significant advantage in aviation.

So, the statement matches how DC powers the controls and sensors with a steady voltage, while AC powers higher‑power components like motors and certain avionics, often at higher frequency. The other options mix up which loads use DC versus AC, or make incorrect claims about voltage and pulsating current.