400 Hz Ground Power & GSE Magnetics
Transformers, reactors and filter inductors for solid-state frequency converters, ground power units and point-of-use 400 Hz distribution.
Magnetics Designed for 400 Hz, Not Adapted From 60 Hz
Aircraft typically use 115/200 V, three-phase, 400 Hz power, and ground support equipment has to deliver it cleanly at the aircraft connector. At 400 Hz, core loss, winding losses and cable reactance all behave differently than at 60 Hz, so a 60 Hz design is not a substitute.
We work with builders and users of frequency converters, ground power units and 400 Hz distribution to specify input transformers, output transformers and filter magnetics for the converter and the cable run. See also our defense & aerospace page.
Typical 400 Hz Applications
- ■ Solid-state frequency converters: 60 Hz input transformers and reactors, and 400 Hz output transformers and filters.
- ■ Point-of-use gate systems: Output isolation and voltage matching close to the aircraft stand.
- ■ Mobile ground power units: Compact, vibration-tolerant 400 Hz magnetics for diesel or electric GPUs.
- ■ Transformer-rectifier units: Transformers and smoothing chokes for 28 VDC ground power.
- ■ Test stands and hangars: 400 Hz distribution for avionics and maintenance test equipment.
400 Hz Magnetics at a Glance
| Component | Typical role | What to specify |
|---|---|---|
| Converter input transformer / reactor | Isolation and harmonic reduction on the 60 Hz side | Input voltage, kVA, rectifier type (6, 12 or 18-pulse) |
| 400 Hz output transformer | Isolation and voltage matching to 115/200 V | kVA, output voltage, regulation, ambient, enclosure |
| Output filter inductor | Shapes the inverter output into a clean sine wave | Inverter switching frequency, current, THD target |
| TRU transformer & DC choke | 28 VDC supply for aircraft systems | DC current, ripple limit, duty cycle |
| Line drop compensation magnetics | Offset voltage drop on long 400 Hz cables | Cable length, gauge, load current |
What to send for a fast, accurate quote
- Output kVA, voltage and frequency
- Input supply voltage and frequency
- Converter topology and switching frequency (for filter magnetics)
- Cable length from converter to aircraft
- Indoor, outdoor, mobile or vibration environment
- Any customer or military standard the equipment must meet
Building or Replacing 400 Hz Equipment?
Send the rating, voltages and environment. The transformer spec sheet includes a 400 Hz option.
Build a transformer spec sheet Contact us400 Hz ground power magnetics: common questions
Why can’t a 60 Hz transformer be used at 400 Hz?
Core loss rises steeply with frequency, and the core steel, lamination thickness and winding design are chosen for the operating frequency. A 60 Hz unit run at 400 Hz can overheat even at light load. A 400 Hz design is also much smaller for the same kVA.
Why does cable length matter so much for 400 Hz ground power?
Cable reactance is proportional to frequency, so the same cable has roughly 6.7 times the reactance at 400 Hz that it has at 60 Hz. Long runs cause significant voltage drop at the aircraft, which is why point-of-use converters or line drop compensation are common.
What voltage do aircraft ground power systems supply?
Most commercial and many military aircraft use 115/200 V, three-phase, 400 Hz AC, and some systems also need 28 VDC. The exact power quality limits come from the aircraft and equipment specifications, which should be included with any request.
Can you quote output filter inductors for a frequency converter?
Yes. Send the inverter switching frequency, output current, the filter capacitance if known, and the target output distortion, and we will request quotations from manufacturers that build filter inductors for that range.