400Hz Frequency Converters

Solid State Aircraft Ground Power Units (GPUs)

When on the ground an aircraft cannot use the domestic 50Hz or 60Hz power. Consequently, whilst parked in the airport apron stand the aircraft utilises the ground support equipment (GSE) to switch its on board service loads and navigation avionics to a 400Hz frequency converter.

Our 400Hz GPU range includes outdoor all weather units that can be used for military airfield and airport applications. These compact converters can be fixed to the gantry of a passenger loading bridge, can be hung underneath the walkway, or the vertically configured systems can be installed at a convenient place close to where the aircraft parks. We also have indoor versions of the GPU for use in maintenance hangars, avionics workshops, hard shelters and simulator applications.

The major benefit to using a "point of use" frequency converter is that it is very energy efficient. The GPU only needs to be switched on when it is needed, which means there is no need continue running the aircraft's engines and the on board turbo generator auxiliary power unit (APU). The 400Hz frequency convertor eliminates noise and air pollution, unnecessary fuel consumption and contributes to the reduction of maintenance needed on the APU, generators and batteries.

We can supply either fixed or mobile units mounted to a trailer in vertical or horizontal configurations.

We can offer a combination converter with both 400Hz power and an additional 28V DC output, for use on helipads on board drilling ships and off-shore oil and gas platforms. We also supply flexibile aircraft power cable, connectors, reeling systems and service pits for stowing the cables that deliver "point of use" power to all types of aircraft. See our Ground Support Equipment section for more information.

Below is our current range of 400Hz frequency converters:  


EF Series 400Hz Frequency Converter

EF 40 Series

These frequency converters utilise the latest in power conversion switching technology to provide all types of aircraft with an extremely flexible and cost effective system designed for 400Hz aircraft ground power applications, for outdoors “point of use” installations.

In contrast to 400Hz systems found in many older airports, the EF 40 GPUs have an inherently high input power factor of 0.98 with low harmonics input stage. The standard output of the system is via a circuit breaker with an electronic protection for indoor use, or with optional contactors for outdoor use and can be delivered with a single output or dual output and supplied with flexible cables fitted with standard aircraft power connectors.

The frequency converters are supplied with 115V single phase output from 1.0kVA to 15kVA and from 10kVA to 100kVA with three phase output. The basic mechanical construction is in vertical format with ingress protection IP31 or IP41 and for outdoors use in IP54 enclosures, there is a horizontal version available for mounting on a mobile trolley, trailer or on floors stands.

The EF 40 series of frequency converters can be installed at aircraft parking stands: in maintenance hangars; and in avionics workshops, aircraft manufacture and training simulators. 

Optional features

  • Analogue supplementary metering
  • 50Hz or 60Hz input frequency
  • Output contactor with interlocking
  • Horizontal configuration for bridge mounting
  • 15 metres flexible cable with aircraft connector
  • No break power transfer to aircraft service
  • Remote monitoring by interface PCB
  • RS485 remote monitoring by computer
  • Second output contactor and interface
  • Ingress protection IP54
  • Line drop compensation
  • Trolley converters 45kVA and 60kVA
  • Special paint colours and finish

 Contact Us for more information or a quote, or click here to Email Us.


Frequency Converter Cabinet

SD Series

The SD series of frequency converters is available in 60kVA with a single output, or 90kVA and 120kVA with one or two output circuits suitable for a wide bodied aircraft. The 180kVA/380 unit is supplied with two 90kVA outputs and is configured so that two 180kVA converters can support the ground power requirements of an Airbus A380.

This 400Hz converter is designed for connecting to the normal 3 phase 50Hz (or 60Hz) mains power source and delivers an output of 200V 3 phase 400Hz power to the aircraft through a single contactor output stage in sizes up to 90kVA or through a circuit breaker when used indoors.

The higher powered ground power units are supplied with two output circuit breakers, interlocks and with two contactors for the outdoor versions.

These "point of use" frequency converters can be supplied with an optional built in NBT feature that allows the converters to synchronise with the on board aircraft power system so the lights, air conditioning system and the avionics continue operating during the change over from aircraft power to the external converter power.

The SDM-M series is the mobile version of this range. The all weather converter is supplied on a trailer as a versatile mobile GPU with 400Hz output 90kVA, 120kVA and 180kVA, and as an option can be configured as a combination converter with a secondary output of 28V DC 600A.

Optional Features

  • Military class rugged construction
  • Ingress protection IP42 and IP54
  • Extended temperature range: from -20C to +50C
  • Dual output for connecting two cables and two aircraft connectors
  • Parallel load sharing configuration for multi-modules
  • Output contactor control interface from the aircraft connector
  • Aircraft interlock bypass circuits
  • No break power transfer to aircraft power circuit
  • Line drop compensation
  • Remote voltage sensing and control for long cable lengths
  • Mobile version on towable trolley or trailer
  • Horizontal style for mounting under passenger loading bridge
  • Secondary output of 28V DC, 600A for battery charging and helicopter engine starting  

Contact Us for more information or a quote, or click here to Email Us.