It has been a long time since I posted here or answered a question, but I am in need of an answer to a question on the power sources for the A319/320 refuel system. I am familiar with the way modern Boeing's provide power to the fueling system. If aircraft power is available via Ground Power or the APU, and the fuel station access panel is open, a rmagnetic reed switch closes and power is provided. If aircraft power is not available, a BATTERY switch can be used to take power from the aircraft battery for fueling. My question on the A319/320 is that I have seen some refueling stations without a BATTERY switch and some with one. If there is no BATTERY switch, how is power provided if there is no aircraft power available? If aircraft power is available, how is the system powered? Is there a similar switch on the fueling station access door?
As always, thanks for your help!