BOMBARDIER Challenger 300, Operating Manual

ELECTRICAL

May 06/2005

Flight Crew Operating Manual

Volume 2

REV 2

CSP 100-6

07-01-03

ELECTRICAL SYSTEM

DESCRIPTION

The Challenger 300 electrical system is a 28 vdc system and divided into two main functions:

- Power generation system
- Power distribution system

The electrical power generation system consists of the following power sources:

- Two main generators provide electrical energy to feed the loads under normal operation in flight and

ground operations. Either one of the engines provides sufficient generator power for normal operations

- One APU generator can share electrical loads with the engine generators at medium and low altitudes or provide

enough electrical generation capability to replace one or both engine generators during failure conditions

- Two onboard batteries that feed the essential loads under emergency conditions when the generators

are inoperative, and on the ground for feeding all loads

- One standby instrument battery located in the nose landing gear bay area. It provides power to the

standby instrument system for approximately 5 hours when fully charged

- One optional hydraulic motor driven generator with a non-time limited source of electrical power in the event total

generated power is lost

- Additonally, an external DC power source for ground operation

The electrical power distribution system consists of four distribution boxes:

- Two of the four electrical distribution boxes are direct current power centers (DCPC). These are located in the aft

equipment bay of the aircraft. They are fed by the power sources listed above and their function is to switch elec-
trical power to the distribution buses and then distribute this power to loads in the aft fuselage of the aircraft

- The other two electrical distribution boxes are secondary power centers. They are located in the equipment rack in

the front fuselage of the aircraft and are fed by the distribution buses of the DCPCs. They distribute electrical
power to the loads in the front fuselage of the aircraft

- Two circuit breaker panels are located in the cockpit. They are fed by the distribution buses of the secondary distri-

bution centers and distribute electrical power to loads which require pilot access to the associated circuit breaker.

- The electrical system is electrically and physically segregated into two channels. External DC power and the APU

generator are arranged to connect to these two channels

COMPONENTS AND OPERATION

ENGINE AND APU GENERATORS

Two engine driven generators, one on each engine accessory section, provide the normal source of 28 volt power to the
airplane. A third identical generator is installed on the APU. All three generators are air cooled and include an integrated
fan. The engine-driven generators automatically come online after the engines are running, the GPU is disconnected, and
the EXT PWR switch on the electrical control panel is depressed, changing the annunciation from ON to AVAIL. The gen-
erators are limited to 12 kVA (400 amp) and the nominal output voltage is 29.5 volts.

When at least two generators are online, the bus tie is normally open. The left generator recharges the left main battery, and
the right generator recharges the right main battery. The generators supply DC power to all DC powered equipment on the
airplane under normal conditions.

EXTERNAL POWER

Ground power can be connected to the airplane through a receptacle located on the lower right side of the fuselage just
below the engine pylon. The anti-flash contactor that connects the output of the GPU to the aircraft electrical system closes
only if the voltage and polarity are within acceptable limits. The acceptable voltage limits are approximately 24 to 32 volts.
The GPU should be regulated to 28 vdc and limited to 1500 amps.

The EXT PWR switch is located on the cockpit electrical control panel. The green AVAIL caption on the EXT PWR switch
illuminates if the GPU is within acceptable parameters. Depressing the EXT PWR switch when the green AVAIL light is
illuminated closes the GPU antiflash contactor, connecting the GPU. The ON caption illuminates, and the green AVAIL
caption extinguishes. The GPU may be deselected with the same switch.

The bus tie contactor automatically closes when a GPU is connected and selected ON. The entire DC system is powered,
assuming the EXT PWR is selected ON.

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