What are the DC buses typically found on the ERJ-145 and what loads do they support?

What are the DC buses typically found on the ERJ-145 and what loads do they support?

• A. Essential DC bus for critical avionics and flight instruments; Nonessential DC bus for noncritical systems; Battery provides DC power during start or AC loss.
• B. Essential DC bus only for flight control; Nonessential DC bus for cabin lighting; Battery for engine start.
• C. Primary DC bus powers all systems; Secondary DC bus powers only lights; Battery is unused.
• D. Essential DC bus powers noncritical systems; Nonessential DC bus powers avionics; Battery only charges TRUs.

Answer: (A)

The key idea is that the ERJ-145 uses two DC power buses to prioritize essential systems while still supplying noncritical ones. The essential DC bus is dedicated to the systems required for safe flight—critical avionics and flight instruments—so these important items stay powered even if electrical conditions are stressed. The nonessential DC bus provides power to noncritical systems, such as cabin lighting and other nonessential equipment, and can be shed if power is limited to protect the essential loads. The aircraft battery supplies DC power during starting and will carry DC power during AC loss, helping to bridge power to the essential bus until generators/TRUs are back online. Transformer-rectifier units normally convert available AC to DC for both buses under normal operation.

The key idea is that the ERJ-145 uses two DC power buses to prioritize essential systems while still supplying noncritical ones. The essential DC bus is dedicated to the systems required for safe flight—critical avionics and flight instruments—so these important items stay powered even if electrical conditions are stressed. The nonessential DC bus provides power to noncritical systems, such as cabin lighting and other nonessential equipment, and can be shed if power is limited to protect the essential loads. The aircraft battery supplies DC power during starting and will carry DC power during AC loss, helping to bridge power to the essential bus until generators/TRUs are back online. Transformer-rectifier units normally convert available AC to DC for both buses under normal operation.