ELECTRICAL
AIRPLANE
OPERATIONS
MANUAL
2-05-05
Page
2
Code
01
REVISION 36
AOM-145/1114
DC SYSTEM
The 28 V DC electrical power system automatically controls power
contactors, fault protection, load shedding and emergency system
operation. This reduces pilot workload during normal operation,
external power supply or system failures. The Electrical Distribution
Logic (EDL) and Generator Control Units (GCU) perform system
management. Detected system failures are automatically isolated,
causing some bus(es) to be deenergized.
Under normal operation, the electrical DC system is divided into
isolated left and right electrical networks. The left network includes
generators 1 and 3, driven by engine 1. Operated in parallel,
generators 1 and 3 are connected to DC BUS 1 to supply ESSENTIAL
DC BUS 1, SHED DC BUS 1 and HOT BUS 1. Battery 1 is charged by
the generators connected to DC BUS 1. Similarly, generators 2 and 4
power the right network and are driven by engine 2.
Both networks are interconnected through Bus Tie Contactors (BTC)
in case of operation with less than four generators. APU generator
may replace any inoperative generator, or may be used before engine
starting when the APU generator or Ground Power Unit (GPU) may
supply the electrical system.
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