What is AC on Boeing 737? (Alternating Current)

The Boeing 737 is one of the most popular aircraft models in the world, known for its efficiency and reliability. But have you ever wondered how this mighty machine is powered? One of the key components that keeps the Boeing 737 running smoothly is Alternating Current, or AC.

Alternating Current refers to the flow of electric charge that periodically reverses direction. In simple terms, it means that the electrons in AC continuously change their flow from positive to negative and back again. This constant oscillation allows for the efficient transmission of electrical energy over long distances and has become the standard method of power distribution in modern aircraft.

On the Boeing 737, AC is generated by the aircraft’s generators, which are typically connected to the engines. These generators produce electrical power as the engines rotate, ensuring a continuous supply of AC throughout the flight. AC power is then distributed to various systems and equipment on the aircraft, including lighting, avionics, communication systems, and more.

AC on the Boeing 737 operates at a frequency of 400 Hz, or 400 cycles per second. This high frequency is chosen for several reasons. Firstly, it allows for the use of smaller and lighter transformers and motors, which are crucial for the space and weight constraints of an aircraft. Additionally, the 400 Hz frequency prevents interference with other electronic devices on the aircraft, such as radios and navigation systems.

Advantages of Alternating Current on Boeing 737

The use of Alternating Current on the Boeing 737 offers several advantages over Direct Current, or DC. One of the main advantages is the ability to use transformers, which allow for voltage conversion and distribution. This is especially useful in aircraft, where different systems and equipment require different voltages to operate efficiently.

Another advantage of AC is its ability to travel long distances without significant power loss. This is due to the fact that AC can be easily stepped up or down in voltage using transformers. For example, AC power can be generated at a higher voltage to reduce power loss during transmission, and then stepped down to the appropriate voltage for use by various aircraft systems.

AC power also allows for simpler and more efficient control and regulation of electrical systems. By using electronic devices such as inverters and rectifiers, AC power can be converted to DC when needed, providing the best of both worlds in terms of power distribution and utilization. This flexibility and adaptability make AC the preferred choice for many aircraft manufacturers, including Boeing.


The use of Alternating Current on the Boeing 737 is an integral part of its electrical system, providing a reliable and efficient source of power for various systems and equipment. With its ability to transmit power over long distances, use transformers for voltage conversion, and offer greater control and regulation options, AC has become the industry standard in modern aircraft.

If you want to learn more about the electrical systems and components of the Boeing 737, check out this article by Boeing. It provides detailed information about the aircraft’s electrical generation and distribution system, including the role of Alternating Current.

For More: What is ASCTS on Boeing 737? (Air Supply Control And Test System)