Guide to 400Hz frequency converters for airports and MROs. Fixed and mobile solid-state ground power from Powervamp, ITW GSE, and AXA Power for commercial aircraft servicing.
What Are 400Hz Frequency Converters?
Most of the aviation world runs on 28V DC, but commercial aircraft — from regional jets to widebody airliners — run their primary electrical systems on 115V AC at 400Hz. This frequency, four times higher than the 50/60Hz wall power available on the ground, was chosen decades ago because it allows smaller, lighter transformers and motors in the aircraft. The consequence on the ground: you need a frequency converter to provide 400Hz power to a parked commercial aircraft, or it must run its APU — burning jet fuel, creating noise, and producing emissions at the gate.
How They Work
A 400Hz frequency converter takes standard utility power (typically 480V 3-phase, 50/60Hz) and converts it to 115/200V 3-phase at 400Hz using solid-state power electronics. Modern units use IGBT inverter technology to produce a clean 400Hz sine wave that meets the stringent power quality standards required by aircraft electrical systems (MIL-STD-704). Output power ranges from 20 kVA for regional jets to 180 kVA for the largest widebodies. The 400Hz output is delivered through a standardized aircraft connector at the gate or parking position.
Manufacturer Comparison
Choosing the Right 400Hz Frequency Converter
400Hz ground power is an airport infrastructure investment, not an aircraft accessory. Individual aircraft operators don't buy frequency converters — airports, FBOs, and MRO facilities install them as part of gate or hangar infrastructure. The investment is justified by fuel savings (eliminating APU use at the gate), noise reduction, emissions compliance, and reduced APU maintenance costs.
The trend in airport design is toward fixed 400Hz installations at every gate position, supplemented by mobile 400Hz units for remote stands and maintenance areas. Fixed installations cost more upfront but eliminate the labor of towing mobile units into position and reduce ground equipment traffic on the ramp.
For the general aviation community, 400Hz power is relevant primarily to operators of larger business jets with AC electrical systems and to MRO facilities that service commercial aircraft. If your aircraft runs on 28V DC (most GA aircraft), you need a DC GPU, not a 400Hz converter.
Power quality is critical. Commercial aircraft manufacturers specify tight tolerances for voltage, frequency, waveform distortion, and transient response. A frequency converter that produces noisy or unstable 400Hz power can cause avionic faults, tripping circuit breakers, and in severe cases, damage to aircraft electrical components. All reputable manufacturers certify their units to relevant MIL-STD and airport authority specifications.
For a step-by-step approach to selecting the right GPU for your aircraft, see our GPU Sizing Guide. For a comparison of lead-acid vs lithium technology, read Lead Acid vs Lithium GPUs.
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Frequently Asked Questions
Do I need 400Hz power for my business jet?
Probably not. Most business jets (Citation, Learjet, Challenger, Gulfstream) use 28V DC ground power for starting and maintenance. Only the largest corporate aircraft with AC electrical buses (some Gulfstream G700 configurations and ACJ/BBJ conversions) may use 400Hz power.
What's the difference between 400Hz and 28V DC ground power?
They're different systems for different aircraft. 28V DC ground power is for starting engines and powering DC electrical systems — used by general aviation, business jets, helicopters, and military aircraft. 400Hz AC power is for commercial aircraft electrical systems and cabin power. Most airports provide both.
How much does a 400Hz frequency converter cost?
Mobile 400Hz units range from $30,000 to $80,000. Fixed installations range from $50,000 to $200,000 depending on capacity and site work. These are airport infrastructure investments, not individual aircraft purchases.