GPUs: The Bigger, the Better?

Some technical standards might require bigger engines than necessary for an operation.

Since that same standard, SAE-APR5015, is now recommending that GPUs should not be used to clear aircraft electrical faults and we have done away with the requirement for 150-percent overload capability, I can’t imagine any practical occurrences where a GPU will be under a full load and then lose it and then immediately regain it; or alternatively, where a GPU will be connected to an aircraft that will instantaneously demand a full load from the GPU.

The reality is that the operator/user is now buying GPUs with engines that are bigger by some 33 percent than before, just to be able to comply with this requirement.

Example? The manufacturer of a GPU rated for 120 kva will have to use an engine that will provide at least 170 kva (215 hp) in order to accommodate sufficient margining for full compliance. If you are curious, this is how it looks for some other GPU sizes:

  • rated: 180 kva; engine required: 325 hp (256 kva)
  • rated: 140 kva; engine required: 276 hp (217 kva)
  • rated: 90 kva; engine required: 100 hp (128 kva)

Who is paying? Mainly the airlines. In addition, the environment; we all pay.

About the author: Arie Tall has held positions as an airline pilot, chief pilot, director of flight operations, and airline VP. He is the business owner of an airline, ground handling company and has taken on the latest challenge of designing and manufacturing GPUs under the name Jetall GPU.

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