曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
brakes with the rudder-pedal toe brakes, and then pull the PARK
BRAKE knob aft.
March 2010
Information Manual 7-49
Cirrus Design Section 7
SR20 Airplane Description
Electrical System
The standard airplane is equipped with 28-volt direct current (VDC)
single alternator electrical system. The system provides uninterrupted
power for avionics, flight instruments, lighting and other electrically
operated and controlled systems during normal operation. The system
also allows load shedding in the event of an electrical system failure.
• Note •
An optional dual alternator system is installed in some airplanes. For a
complete description of the system, refer to 11934-S10, POH
Supplement for Dual Alternator System.
Power Generation
Primary power for the SR20 is supplied by a 28-VDC negative-ground
electrical system. The electrical power generation system consists of a
24-volt, 10-amp-hour battery, a 75-ampere alternator, a voltage
regulator and an over-voltage protection system. The battery is an
aviation grade, 12-cell lead-acid type with non-spill vent caps. The
battery is used for engine starting and as an emergency power source
in the event of alternator failure. The 75-ampere alternator provides
constant charging current for the battery and primary power to the
aircraft electrical system during normal system operation. The voltage
regulator provides transient suppression and constant voltage
regulation of the unfiltered alternator power. To protect sensitive
instruments, the over-voltage protection system monitors the primary
power bus and automatically limits the peak voltage to 28.5 volts.
During sustained over-voltage and under-voltage periods, the overvoltage
system provides a warning to the pilot.
March 2010
7-50 Information Manual
Section 7 Cirrus Design
Airplane Description SR20
Figure 7-10
ALT.
CNTL.
UNIT
25A
(MCU)
MASTER CNTL. UNIT
MASTER
1
ALTERNATOR
ALT.
RELAY
EXTERNAL
POWER
RECEPTACLE
STARTER
GND.
PWR.
RELAY
INST. LIGHTS
PITCH TRIM
ROLL TRIM
ESSENTIAL I
AVIONICS
AVIONICS
CIRCUIT BREAKER PANEL
COM I
GPS 1
ENCODER/TRANS
AUDIO PANEL
HSI
ANNUN. POWER
TURN COORD.
ENGINE INST.
ALTERNATOR
ESSENTIAL ESSENTIAL
MAIN BUS 1 NON-ESSENTIAL
MAIN BUS 2 NON-ESSENTIAL
SR20_FM07_1018B
15A
25A
25A
5A
LOW VOLTS
ANNUNC.
CLOCK
BATTERY
VOLTS AMPS
3
LANDING
LIGHT
LANDING
LIGHT
LANDING
LIGHT RELAY
STANDBY VACUUM
IGNITION
3
1
2
2
STARTER
RELAY
CURRENT
SENSOR BATTERY
RELAY
AVIONICS
(START)
SEE VACUUM SYSTEM
IN THIS SECTION
STARTER RELAY
AUXILIARY PWR. 28VDC
CONVENIENCE
POWER 12VDC
PITOT HT./
COOLING FAN
FLAPS
FUEL PUMP
NAV LIGHTS
CABIN FLOOD LIGHTS
STROBE LIGHTS
ESSENTIAL 2
COM 2
GPS 2
MFD
ADF
STORM SCOPE
DME
AUTO PILOT
ALT.
BAT.
Electrical Power & Distribution
March 2010
Information Manual 7-51
Cirrus Design Section 7
SR20 Airplane Description
Power Distribution
Power distribution for the SR20 consists of the electrical power bus in
the Master Control Unit (MCU), Main Buses, Essential and Non-
Essential buses in the circuit breaker panel, as well as associated
fuses, circuit breakers and switches. The main power buses (Main Bus
1 and Main Bus 2) and the Non-Essential equipment bus receive
power from the power generation system through 25-amp feeder bus
fuses or circuit breakers located in the Master Control Unit (MCU). The
Essential power bus is powered from Main Bus 1 and Main Bus 2 from
the Essential 1 and Essential 2 circuit breakers through a network of
diodes. The Non-Essential avionics bus and the Essential avionics bus
are powered from Main Bus 1 and the Essential power bus
respectively through the associated Avionics circuit breakers provided
the AVIONICS POWER switch is ON. Avionics loads on the avionics
buses can be shed by pulling the associated Avionics circuit breaker.
BAT & ALT Master Switches
The rocker type electrical system MASTER switches are ON in the up
position and off in the down position. The right switch, labeled BAT,
controls all electrical power to the airplane. The left switch, labeled
ALT, controls the alternator.
Normally, both master switches will be ON. However, the BAT switch
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