What is the electrical system specification for the airplane described?

What is the electrical system specification for the airplane described?

• A. 24 volt, 60 amp alternator and 28 volt battery
• B. 28 volt, 40 amp alternator and 24 volt battery
• C. 28 volt, 60 amp alternator and 24 volt battery
• D. 24 volt, 40 amp alternator and 12 volt battery

Answer: (C)

The idea is to design the electrical system to meet all loads reliably while using a voltage that minimizes current and provides adequate charging headroom. A 28-volt system allows the same power to be delivered with less current than a 24-volt system, which reduces wiring size and losses. The alternator needs to be sized to cover normal loads plus charging, so a 60-amp unit gives ample capacity for avionics, lighting, pumps, and startup surges. Pairing that with a 24-volt battery provides a solid reserve and starting capability while the 28-volt system can efficiently charge it. The 24-volt battery is a common choice for this setup because it can be safely charged by a 28-volt regulator and serves as the backup when the alternator isn’t supplying power. Other configurations mix incompatible voltages or undersize the charging capability, which could lead to insufficient power during peak demand or improper charging.

The idea is to design the electrical system to meet all loads reliably while using a voltage that minimizes current and provides adequate charging headroom. A 28-volt system allows the same power to be delivered with less current than a 24-volt system, which reduces wiring size and losses. The alternator needs to be sized to cover normal loads plus charging, so a 60-amp unit gives ample capacity for avionics, lighting, pumps, and startup surges. Pairing that with a 24-volt battery provides a solid reserve and starting capability while the 28-volt system can efficiently charge it. The 24-volt battery is a common choice for this setup because it can be safely charged by a 28-volt regulator and serves as the backup when the alternator isn’t supplying power.

Other configurations mix incompatible voltages or undersize the charging capability, which could lead to insufficient power during peak demand or improper charging.