Comparing the Reliability of APUs and GPUs

Written by: Start Pac

Aircraft operations consist of two cycles, landing and take-off, and the cruise phase. Both cycles are crucial in terms of a plane’s functionality. The landing and take-off phase includes taxiing, taking off, climbing out, approaching, and landing. Now, this cycle can be subdivided into two separate operations – departure and arrival. This includes the landing roll, taxi in, reverse thrust, taxiway acceleration, etc.


Auxiliary Power Unit Breakdown

Throughout the course of the flight, there is auxiliary power unit (APU) usage. When the plane is taxiing in and out, the APU is used – for both arrival and departure. APU’s are typically used in ships, aircrafts, and vehicles as a form of supplementary power for onboard entertainment, navigation, or air conditioning. It’s a steady stream that essentially provides power to the entire plane. The main purpose of an APU, when it comes to gas propulsion, is to generate electricity, start the main engines, and supply a current when the plane is idling in air. Additionally, they’re also used to minimize performance loss of propulsion during flight.

Ground Power Unit Breakdown

A ground power unit (GPU), on the other hand, is a portable diesel-powered electrical supply system. If an aircraft does not have an APUT or when there are airport management constraints, ground power units are brought in to do their job until the main aircraft engines start. You’ll typically see them at airports being pulled along by a cart. Or, more advanced airports will have them built already into the ground at each terminal, with the wiring all leading back to a central power supply.

Many ground power units come in a 24 volt power supply and up. The immense amount of power that these units can produce is enough to power up a larger craft.

The Bottom Line

Although both APUs and GPUs essentially perform the same tasks, they’re both still used in a variety of airports today. The reason behind this is that GPU’s diesel power is a more reliable option than the APU. This isn’t to say that APU’s aren’t up to standard. However, ground power units have a higher capability of providing a current stream of power. Many private air fields carry numerous ground power units and 28 volt power supplies for electrical purposes. The bottom line is that both APUs and GPUs continue to be used in conjunction with each other because of their unique powering capabilities.