Operation Manual – AXA 2400 Compact – 30 - 90 kVA
Options
Document no. 578.650BB
Page 74 of 91
578809
Door Interlock (Diagram 478801)
The door interlock ensures that the ground power unit’s output
contactor(s) opens and the unit immediately returns to standby
mode if the door is opened.
578810
Neutral Conductor Rupture Supervision
A broken neutral conductor in the 400 Hz cable combined with an unbalanced aircraft load could lead to
a destructive phase-neutral voltage in the aircraft and to hazardous voltages between the aircraft chassis
and ground. The NCR option ensures that a broken neutral will be detected immediately.
Principle wiring diagram for Neutral Conductor Rupture Supervision
Unbalanced voltage at the aircraft connector due to a broken neutral would add a 400 Hz voltage to the
28 VDC interlock voltage measured at the ground power unit. If the injected AC voltage exceeds
approx. 10 VAC the output is disconnected. This type of error is recognised as an interlock failure by
the ground power unit. Since the disconnection is a reaction to a heavy unbalanced voltage at the
aircraft connector, it means that this type of supervision does
not
protect sensitive equipment in the
aircraft. The NCR option protects personnel as well as the aircraft in case of a broken neutral.
Note!
In general ITW GSE does not recommend the NCR option for the following reasons:
