Electrical System - Cessna Grand Caravan 208B G1000 Manual

CESSNA SECTION 7
MODEL 208B G1000 AIRPLANE AND SYSTEMS DESCRIPTION

ELECTRICAL SYSTEM

The airplane is equipped with a 28-volt, direct-current electrical system
(see Typical Electrical System figure). The system uses a 24-volt
sealed lead acid battery; located on the front right side of the firewall,
as a source of electrical energy. A 200-amp engine-driven starter-
generator is used to maintain the battery's state of charge. Power is
supplied to most general electrical and all avionics circuits through two
general buses, two avionics buses, and a hot battery bus. The battery
bus is energized continuously for cabin/courtesy lights and functions
requiring power when the two general busses are off. The two general
buses are on anytime the battery switch is turned on. All DC buses are
on anytime the battery switch and the two avionics switches are turned
on.
STANDBY ELECTRICAL SYSTEM
The standby electrical system serves as a power source in the event
the main generator system malfunctions in flight. The system includes
an alternator operated at a 75-amp capacity rating. The alternator is
belt-driven from an accessory pad on the rear of the engine. The
system also includes an alternator control unit located forward of the
circuit breaker panel, a standby alternator contactor assembly on the
left front side of the firewall and two switches on the left sidewall switch
panel, labeled STBY ALT POWER and AVIONICS STBY PWR.
Circuit protection and isolation is provided by two circuit breakers,
labeled STBY PWR, on the left sidewall circuit breaker panel. Field
excitation to the alternator control unit is supplied through diode logic
from a circuit breaker in the standby alternator relay assembly or from
the HOURMETER/ACU circuit breaker in the main power relay box.
Standby Electrical system monitoring is provided by CAS messages;
White STBY PWR ON CAS MSG and Amber STBY PWR INOP CAS
MSG. Total amperage supplied from the standby electrical system can
be monitored on the EIS SYSTEMS DISPLAY. Additionally, an ALTNR
AMPS CAS message is provided if the standby alternator amperage
draw exceeds normal operating ranges.
208BPHBUS-00 7-71
U.S.