Electrical System; Standby Electrical System - Textron Cessna Grand Caravan Ex 208B Pilot's Operating Handbook And Faa Approved Airplane Flight Manual

CESSNA SECTION 7
MODEL 208B 867 SHP AIRPLANE AND SYSTEMS DESCRIPTION
GARMIN G1000

ELECTRICAL SYSTEM

The airplane is equipped with a 28-volt, direct-current electrical system,
refer to Figure 7-12, Electrical System. 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 buses 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 PWR 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 annunciators; white
STBY PWR ON annunciator and amber STBY PWR INOP annunciator.
Total amperage supplied from the standby electrical system can be
monitored on the EIS SYSTEMS DISPLAY. Additionally, an amber
ALTNR AMPS annunciator is provided if the standby alternator
amperage draw exceeds normal operating ranges.
208BPHCUS-00 7-89
U.S.