Soft Start for your Foxcart Ground Power Unit

A small-yet-valuable feature that helps protect and prolong the life of your aircraft’s engine, invest in a FoxCart GPU equipped with Soft Start.

Ground power units give life to your unpowered aircraft

What is Soft Start for aircraft ground power units and why use it?

Explore Soft Start on the FoxCart 1600 and FoxCart 2000 ground power units (manufactured by Unitron)


Ground power units give life to your unpowered aircraft

An essential piece of equipment for aircraft owners, maintenance and flight crew, a ground power unit (GPU) is a type of ground support equipment (GSE) that is used to provide power to an unpowered aircraft while it is not in flight (on an airport runway, an airfield, or anywhere on the floor). A GPU allows operators to provide DC and/or AC power to the aircraft to help start engines, perform maintenance, or provide general onboard power while the aircraft is in the hangar or on the ramp.

What is Soft Start for aircraft ground power units and why use it?

Soft Start is a limiter that can be either added into FoxCart’s GPU during manufacturing or at a later date. As an available option, Soft Start limits the output current of the GPU and will allow the voltage from the aircraft to automatically decrease as more current is drawn from the unit. Its purpose is to soften the inrush of current from the GPU when the starter of a turbine engine is first engaged to protect the starter from being over torqued and the solenoid contacts from arcing.

On inrush, the Soft Start drops the voltage as needed to limit the current to around 1000 amps in order to stay connected. As the engine spools up, the voltage will return to 28 volts. On some aircraft, the battery must be turned on in order to be able to inject external power into the start system. In this type of arrangement, the aircraft batteries and GPU are in parallel. On a start, the engine draws power from both the batteries and the GPU. If the Soft Start is switched on, the batteries will furnish about 80% of the power and the GPU about 20%. With the Soft Start switched in normal position (or out of the circuit), the reverse is true - 80% will come from the GPU and 20% from the aircraft batteries as it should. On aircraft where the start can be supplied from external, the GPU will supply 100% of the power.

A smart return on investment, Soft Start will help protect and prolong the life of your aircraft’s engine. As a limiter that controls and allocates the amount of voltage being used by both the aircraft and the ground power unit, Soft Start prioritizes the use of power generated from the GPU as opposed to the aircraft’s internal battery.

Explore Soft Start on the FoxCart 1600 and FoxCart 2000 ground power units (manufactured by Unitron)

FoxCart 1600

The FoxCart Series 1600 mobile GPU automatically provides plug-head performance IAW ISO 6858 within the limits of ISO 461-1 for output cables up to 20 feet in length when functioning as a maintenance, repair and engine start cart. This 28VDC GPU supports aircraft requiring typical loads up to 400 amps continuous rating. Engine starting currents up to 1600 amps are provided when operating from a 60Hz source and 1200 amps when operating from a 50Hz source.

FoxCart 2000

The FoxCart Series 2000 mobile GPU automatically provides plug-head performance IAW ISO 6858 within the limits of ISO 461-1 for output cables up to 20 feet in length when functioning as a maintenance, repair, and engine start cart. This 28VDC GPU supports aircraft requiring typical loads up to 600 amps continuous. Engine starting currents up to 2000 amps are provided when operating from a 60Hz source up to 1800 amps when operating from a 50Hz source.

Contact the knowledgeable PJI team to help you identify the most efficient FoxCart ground power unit with the Soft Start feature for your aircraft.

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