pawan kumar
.Posted in Why we do not use CSD in APU?
Apu's don't have mechanical governors. the fadec or engine controller governs the apu. it watches rpm and egt. the only time the apu will exceed 98-100% is on main engine start (goes to 102%). the apu shuts down by sending a false overspeed signal to the fadec. back to the question.. the rpm of the apu is what is maintaining the constant speed. it is also much lighter in weight this way. a 90kva idg weighs about 120 lbs. the apu generator is about 50 lbs
Ramanjeet Singh
.Posted in Why we do not use CSD in APU?
Its simple APU is running at fixed RPM. i.e.100%..... fixed RPM mean fixed frequency i.e 400hz...... when the requirment is more for bleed that time RPM getting increased but that is control by ELECTRONIC CONTROL BOX(ECB).