ITW GSE 4400 Tier 4, Manual

Page: 108 / 126

Operation Manual – ITW GSE 4400 Tier 4
ARU Transformers (T20):
The ARU transformers steps down the 3 phased 400 Hz voltage (3 x 200 Vac) to an appropriate level for
obtaining 28 VDC at the output.
ARU Rectifier (PM20):
The output voltage is kept at 28 VDC by using thyristors, regardless of the input voltage level and the
load.
ARU Board (A20):
The ARU Board interfaces with the processor board and the rest of the 28 VDC unit.

Supplied from PS1 (X2)

Connection to ARU control input on A2 (X1)

Control of thyristors.

Measures the output voltage.

Opens and closes the 400 Hz Input Contactor Q3

Interface for heatsink thermostat (X5)

Input for current transformer T20 (X6)
Resistor (R20):
The discharge resistor R20 is part of the output filter stage and discharges the capacitor C20, when the
unit is turned off.
Filter Capacitors (C20)
The output filter capacitors are also part of the output filter stage and secures that the AC ripple is kept to
a minimum, less than 2% at the output.
Fan (M20)
The fan M20 is part of the total forced cooling of the unit, the primary task for the fan is to cool down the
rectifier module.
A.2 Connection of Cables
Fig. A-2-1 Connection of Cables
Recommended output cable to the aircraft is 2 x 4/0 (95 mm²) for continuous loads up to 400 amps (as
shown above) and 4 x 4/0 (95 mm²) for higher continuous loads.
OM2247 Rev B Page 107 of 125