Generator Control Unit; Ground Power Monitor; Battery Switch - Textron Cessna Grand Caravan Ex 208B Pilot's Operating Handbook And Faa Approved Airplane Flight Manual

SECTION 7 CESSNA
AIRPLANE AND SYSTEMS DESCRIPTION MODEL 208B 867 SHP
GARMIN G1000
ELECTRICAL SYSTEM
(Continued)

GENERATOR CONTROL UNIT

The generator control unit (GCU) is mounted inside the cabin on the left
forward fuselage sidewall. The unit provides the electrical control
functions necessary for the operation of the starter-generator. The GCU
provides for automatic starter cutoff when engine RPM is above 46%.
Below 46%, the starter-generator functions as a starter, and above
46%, the starter-generator functions as a generator when the
STARTER switch is OFF. The GCU provides voltage regulation plus
high voltage protection and reverse current protection. In the event of a
high-voltage or reverse current condition, the generator is automatically
disconnected from the buses. The generator contactor (controlled by
the GCU) connects the generator output to the airplane bus. If any
GCU function causes the generator contactor to de-energize, the
amber GENERATOR OFF annunciator will illuminate.

GROUND POWER MONITOR

The ground power monitor is located inside the electrical power control
assembly mounted on the left hand side of the firewall in the engine
compartment. This unit senses the voltage level applied to the external
power receptacle and will close the external power contactor when the
applied voltage is within the proper limits.

BATTERY SWITCH

The BATTERY switch is a two-position toggle-type switch, labeled
BATTERY, and is located on the left sidewall switch and circuit breaker
panel. The BATTERY switch is ON in the forward position and OFF in
the aft position. When the BATTERY switch is in the ON position,
battery power is supplied to the two general buses. The OFF position
removes power to all buses except the battery bus.
7-90 208BPHCUS-00
U.S.