Carbon Cycle Chemical Reactions Involved: Photosynthesis: Air and water molecules and the energy from the sun to produce a simple sugar such as glucose and oxygen molecules as a by product. During photosynthesis plants use carbon dioxide and produce oxygen.
Similar to shore power for ships, a ground power unit (GPU) may be used to supply electric power for an aircraft on the ground, to sustain interior lighting, ventilation and other requirements before starting of the main engines or the aircraft auxiliary power unit (APU).
At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path.