BOMBARDIER Challenger 300, Operating Manual

ELECTRICAL

May 06/2005

Flight Crew Operating Manual

Volume 2

REV 2

CSP 100-6

07-01-05

ELECTRICAL SYSTEM (Cont)

BATTERIES

The batteries are located in the fuselage fairing aft of the left wing. During APU start, the right battery is isolated from the
rest of the aircraft and provides power to the APU starter. The bus tie closes and the left battery provides power to the rest
of the aircraft for emergency operation during total generator failure. They also provide power to the battery buses even
when the batteries are selected off.

The standard batteries are 24 volt nickel-cadmium (NICAD) rated at 44-amp hr.

Gases produced by the main batteries are vented overboard through two tubes that extend from the battery cases. 

The batteries are connected to the essential buses when the contactors are closed. When a generator is online, it is connected
to the main buses and charges the battery.

When the batteries are connected on their corresponding buses in parallel with the generators, they are charged by the gen-
erators.

Individual battery voltages and temperatures can be read on the ELECTRICAL and SUMMARY synoptic displays on the
MFD.

During a total generator failure, the aircraft batteries provide power for necessary essential equipment for a
limited duration.

Standby Instrument power is supplied by a dedicated 24 vdc battery. The standby instrument is activated by a separate
STBY INST switch located on the ELECTRICAL power panel.

If the batteries are allowed to significantly discharge prior to bringing a generator on-line, the charging current may be large
enough to result in a APU GEN OVERLOAD, or L (R) GEN OVERLOAD caution CAS message for a short time as the
batteries recharge.

POWER CENTERS

The two DC power centers (left and right) provide the following functions:

- Protect the loads from abnormal electrical power quality
- Control and reconfigure the distribution system in response to manual switching or when a fault occurs. This

reconfiguration shall ensure the supply of the buses in accordance with an established priority relating to the power
sources available

- Ensure the coupling of the two channels on the ground when only batteries or external DC power are available, or

in flight when only one generator is available

- Control the automatic load shedding
- Isolate the faulted distribution buses when a short circuit occurs on a feeder or on a bus
- Distribute the electrical power to loads located in the aft of the aircraft
- Distribute the electrical power to secondary power centers located in the front fuselage of the aircraft
- Protect distribution cables from short circuit

Additionally, there is an Auxiliary Power Center for the APU Generator.

REV 2