Learjet 60 - DC Power Distribution

Learjet 60

Pilot's Manual
DC POWER DISTRIBUTION
SWUM ae
ELECTRICAL &
LIGHTING
Primary
electrical power for aircraft and avionics systems
requiring
DC power is supplied
by two engine-driven, 30-volt,
400-ampere
starter/generators . Secondary
DC electrical power is supplied
by two
24-volt lead-acid
(standard) or nickel-cadmium (optional)
batteries .
An external power receptacle
is installed for engine start and
station-
ary ground operations .
A generator control unit (GCU) is installed
for each starter/ generator .
The
GCUs
contain circuits to maintain
generator output at approxi-
mately 28 VDC throughout varying
engine speeds and loads .
The
GCUs
also contain circuits to equalize
generator load during
parallel
operation, provide overvoltage
protection, and provide
current limit-
ing during ground
operations and during generator-assisted
cross
starts .
Duringnormal operation, the
generators supply all aircraft DC
power
requirements . Regulated 28 VDC
output from the generators
is ap-
plied to the respective
generator buses . The voltage
on the generator
buses is applied to the
battery charging bus through
275-amp current
limiters . Battery charge
is maintained from the
battery charging bus
through the battery relays
and battery buses . The DC
BUS 2 and 3
buses
in
the
circuit breaker panels are
powered from the respective
generator buses through 50-amp current
limiters . The DC BUS 4
bus-
es in the circuit breaker panels are
powered from the battery
charging
bus through 40-amp current limiters
. The battery bus in the
pilot's cir-
cuit breaker panel is powered
from the #1 battery through a
20-amp
current limiter . The battery bus
in the copilot's circuit
breaker panel is
powered from the #2 battery
through a 10-amp
current limiter . The
DC BUS 1 buses in the
circuit breaker panels are
powered from the re-
spective generator bus
through an overload sensor
and a control re-
lay . A CABIN
PWR BUS is installed in the pilot's
circuit breaker
pan-
el . The CABIN
PWR BUS is powered from
the battery charging bus
through a 100-amp current
limiter, an overload
sensor, and a control
relay . The
inverters are powered through
overload sensors and con-
trol
relays . Additionally, aircraft systems
producing heavy loads ;
such as
resistance heaters, freon compressor, large
lamps, inverters,
blowers,
heavy-duty motors, and heavy-duty
pumps, are supplied
power
through current limners connected to either
the battery charg-
ing bus or
generator buses .
PM-123
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