Power Distribution - Cirrus SR22 Pilot Operating Handbook

Section 7 Cirrus Design
Airplane Description SR22
and overcurrent annunciations. Power is distributed to the airplane
circuit panel buses through Main and Essential buses in the MCU.
During normal operation, the alternators feed their respective
Distribution Bus independently (ALT 1 feeds Main Distribution Bus and
ALT 2 feeds the Essential Distribution Bus). The distribution busses
are interconnected by two 50-amp fuses and a diode. The diode
prevents ALT 2 from feeding the Main Distribution Bus. Additionally,
since ALT 2 / Essential Distribution Bus voltage is slightly higher than
ALT 1 / Main Distribution Bus voltage, ALT 1 will not feed the Essential
Distribution Bus unless ALT 2 fails.

Power Distribution

The power distribution system for the SR22 consists of the Main
Distribution Bus and the Essential Distribution Bus in the MCU and
associated buses in the Circuit Breaker panel. The circuit breaker
panel is located on the left side of the console next to the pilots right
knee.
For normal operation, the Essential Buses in the circuit breaker panel
are powered from the Essential Distribution Bus in the MCU through
25-amp circuit breakers. BAT 2 is connected directly to the Essential
Bus in the circuit breaker panel and will power the bus should the
voltage coming from the MCU distribution buses drop below the
battery voltage. Additionally, in the event of an ALT 2 failure, the circuit
breaker panel Essential Bus will be powered from ALT 1 through the
Main distribution and Essential distribution buses in the MCU. Main
Bus 1, Main Bus 2, and the equipment Non-Essential Bus in the circuit
breaker panel are powered from ALT 1 through the Main Distribution
Bus in the MCU. The Avionics Non-Essential Bus in the circuit breaker
panel is powered from Main Bus 1.
7-66 P/N 13772-001
Revision A5