Why are isolation transformers used in avionics power supplies, and what benefits do they provide?

Why are isolation transformers used in avionics power supplies, and what benefits do they provide?

• A. They provide galvanic isolation and fault/noise protection and allow different reference grounds without sharing return currents.
• B. They increase current capacity without changing voltage.
• C. They convert DC to DC and store energy in a core.
• D. They are primarily used to reduce EMI without isolation.

Answer: (A)

Isolation transformers in avionics power supplies provide galvanic isolation between the aircraft system and the power source, so there is no direct electrical path for fault currents or DC currents between them. This protects equipment and people, and keeps a fault on one side from propagating to the other. They also break ground loops and help block common-mode noise, reducing interference that could travel from the power line into sensitive avionics. Because the secondary can reference to its own ground without sharing a return path, different reference grounds can be used safely without unwanted current flowing through a common return. In short, isolation is the primary benefit for safety and fault protection, with noise and EMI suppression as important accompanying effects. The other options don’t describe what an isolation transformer actually does: they don’t correctly reflect how isolation and ground separation, fault protection, and safety are achieved, and they mix in functions (like DC-DC conversion or simply increasing current) that aren’t the transformer’s purpose.

Isolation transformers in avionics power supplies provide galvanic isolation between the aircraft system and the power source, so there is no direct electrical path for fault currents or DC currents between them. This protects equipment and people, and keeps a fault on one side from propagating to the other. They also break ground loops and help block common-mode noise, reducing interference that could travel from the power line into sensitive avionics. Because the secondary can reference to its own ground without sharing a return path, different reference grounds can be used safely without unwanted current flowing through a common return. In short, isolation is the primary benefit for safety and fault protection, with noise and EMI suppression as important accompanying effects. The other options don’t describe what an isolation transformer actually does: they don’t correctly reflect how isolation and ground separation, fault protection, and safety are achieved, and they mix in functions (like DC-DC conversion or simply increasing current) that aren’t the transformer’s purpose.