Our new SD series of solid state frequency converters are derived from our long experience in the design and manufacture of rectifiers, inverters, UPS systems and frequency converters. This 400Hz frequency converter range includes outdoor all weather units that can be used for military airfield and airport applications. The 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 ground power unit (GPU) for use in maintenance hangars, avionics workshops, hard shelters and simulator applications.